this work was carried out under the supervision of ... · these findings, combined with dft...

This work was carried out under the supervision of Professor David Milstein

Department of Organic Chemistry The Weizmann Institute of Science

Rehovot, Israel

.ב"בתמוז תשס' ח, שנספה בפיגוע בצומת פתעמיתחבר ו, עבודה זו מוקדשת לזיכרו של רפאל ברגר

This work is dedicated in the loving memory of Refael Berger a friend and a college which was killed in a terror attack at "Pat" junction in Jerusalem, June 2002.

I want to thank Prof. David Milstein for his Patience, devotion and the opportunity he gave me to gain some wisdom from the vast throve he has. I thank Yehoshua for making every day a joy in the lab and the members of the for their friendship and support. I want to thank especially to my parents for all they have done on for me during this period. Finally, I am grateful for my beloved wife for her love and devotion.

Abstract

The main theme of our research deals with the insertion of transition metals (Ir and Rh) into unactivated

C-H bonds. The research resulted in two main discoveries. The fisrtdiscovery is the selective C-H bond

activation of haloarenes. We have shown, for the first time, that even in the presence of the normally

more active C-halide bonds, the C-H activation process can occur selectively, and at the most sterically

demanding position, ortho- to the halide atom. No C-halide bond cleavage was observed. We have shown

that the C-H activation process at the ortho- position is both thermodynamically and kinetically more

favorable than C-halide activation.

These findings, combined with DFT calculations (performed by Revital Cohen in Prof. Martin's

group) provided mechanistic insight into the selective C-H bond activation process. Theory supported our

assumption that halide coordination to the metal center prior to C-H activation is a crucial step.

Moreover, coordination of the halide is important for stabilization of the complex formed after C-H

activation. A comparison between the C-H activation products of the haloarenes (fluoro-, chloro- and

bromobenzene) revealed that the coordination ability of the halide corresponds to the relative kinetic

stability of these three complexes.

The second main discovery is the C-H bond activation of benzene by a neutral IrI complex without an

overall change in metal oxidation state, resulting in an IrIPh complex. Moreover, we have discovered the

stereoselective activation of H2 by IrIII in an overall apparent oxidative addition of H2 by IrI. In general,

we presented metal-ligand cooperation in C-H and H2 activation by electron rich IrI and RhI complexes

where aromatization/dearomatization plays a key steps.

Another topic of our research deals with double α-C-H bond activation of various ethers (aromatic

and aliphatic) to form Fischer-type carbenes. We have shown that the process of α-H elimination is

reversible, and is more facile when a more electron-rich carbene is formed. Moreover, β-H elimination is

much less facile than α-H elimination in ethers containing β-hydrogens (THF). However, β-H elimination

prevails when the (tBuPNP*)Ir(I)(COE) neutral system is involved. Fischer-type carbenes are sensitive to

nucleophilic attack, which can result in a C-O bond cleavage, but such a process was rarely observed with

late transition metals carbenes. The (PNP)Ir Fischer-type carbene exhibited such reactivity. We have also

shown that dehydrogenation of the α-alkyl group can result in H2 elimination, depending on the counter

anion used.

The reactivity of (iPrPNP)Ir(I) (iPrPNP = 2,6-bis(di- iso-propylphosphinomethylene)pyridine) toward

C-H and H-H bonds was compared to that of the bulkier (tBuPNP)Ir(I), showing that the steric

environment around the metal center can have a major effect on the reactivity.

A more recent topic of our research deals with O2 activation by PNP- type Ir(I) and Rh(I) hydrides. In

particular, insertion of the O-O bond into the M-H bond to yield metal hydroxo- complexes. Our results

indicate that these reactions are most probably not free radical reactions, and are bimolecular.

The reactivity of the de-aromatized, PNP Ir(I) system was studied with a few substrates (e.g. H2,

Ph2SiH2, CO2); in most cases it was shown that the de-aromatized ligand is not innocent, and takes an

active role in the activation of those molecules.

The synthesis and reactivity of PNP based Rh complexes (neutral and cationic) was studied. While the

process of C-H bond cleavage was not observed in the cationic Rh system (due to lower stability of the

alkyl hydride as compared with the Ir(I) cationic system) the neutral Rh system was shown to activate the

C-H bond of benzene, resulting in a Rh (I) phenyl complex.

List of Abreviations

tBu2PNP 2,6- bis(di-tert-butylphosphinomethylene)pyridine

iPr2PNP 2,6- bis(di-iso-propylphosphinomethylene)pyridine

PNN (2-(di-tert-butylphosphinomethylene, 6-( di-ethylaminomethylene))pyridine

COE Cyclooctene

THF Tetrahydrofuran

M-H Metal-Hydride

BDE Bond Dissociation Energy

L Ligand

BArF Tetra (1,3- bis(trifluoromethyl)benzene, 5-)borate

COSY COrrelation SpectroscopY

NOE Nuclear Overhauser Effect tBuOK Potassium tert-butyloxide

Ph Phenyl

1 Introduction .................................................................................................................. 1

1.1 General ..........................................................................................................................................................1

1.2 Oxidative Addition........................................................................................................................................2

1.3 Sigma-Bond Metathesis ................................................................................................................................3

1.4 Migratory Insertion/ β-H Elimination. ..........................................................................................................3

1.5 α-H Elimination ............................................................................................................................................5

1.6 The Choice of a Ligand: Pincer Type Ligands .............................................................................................5

1.7 Aromatic C-H Bond Activation ....................................................................................................................6

1.8 Fischer-Type Carbenes .................................................................................................................................8

1.9 Hydrocarbons Oxidation by Molecular Oxygen ...........................................................................................9

2 Research Objectives ................................................................................................... 10

3 Results and Discussion ............................................................................................... 11

3.1 Ortho C-H Activation of Haloarenes and Anisole by An Electron Rich Ir(I) Complex.............................11

3.1.1 Reaction of (tBuPNP)Ir(COE)+ With Benzene .............................................................................. 13

3.1.2 Reaction of (PNP)Ir(COE)+ 1 With Aryl Halides ......................................................................... 17

3.1.3 Reaction of (tBuPNP)Ir(COE)+ With Anisole. .............................................................................. 21

3.1.4 Exchange Reactions................................................................................................................... 24

3.2 C-H Vs. H2 Activation by An Electron-Rich PNP Ir(I) System:(iPr2PNP)Ir(I) vs. (tBu2PNP)Ir(I) . ..........25

3.2.1 Vinylic C-H Bond Activation of COE .......................................................................................... 28

3.3 Double α-C-H Activation of Aliphatic and Aromatic Ethers......................................................................30

3.3.1 Double α-C-H Activation of THF. Reversible α- Hydride Elimination. ...............................................30

3.3.2 Dehydrogenation of The α-C Position of THF and TBME; Counter-Anion Effect. .............................33

3.3.3 Oxidation Dependent β-H Elimination?! Triple C-H Activation of THF by (tBuPNP)Ir(I)(COE).......34

3.3.4 Fischer-Type Carbenes of Aromatic Ethers Other Than THF. Csp3-H vs Csp2-H Activation. .............. 35

3.4 Metal - Ligand Cooperation in C-H and H2 Activation by An Electron-Rich PNP Ir(I) System. ..............41

3.5 Activation of H2 and Vinylic C-H by The Neutral (tBuPNP*)Ir(I)(COE) (iPrPNP*)Ir(I)(COE)................48

3.6 Oxygen Insertion Into M-H Bonds (M= Ir, Rh)..........................................................................................51

3.7 C-X Bond Activation (X= Br, Cl or O) by PNP Based Iridium and Rhodium Complexes. .......................54

3.8 PNP Based Rhodium Complexes. Synthesis and Reactivity. .....................................................................59

3.9 Nucleophilicity of (PNP)IrIPh. Reactivity With MeI, I2 and CO2...............................................................62

3.9.1 Ligand Assisted Activation of Diphenylsilane and CO2 by The (tBuPNP*)IrI(COE) Neutral Complex .... 67

4 Experimental............................................................................................................... 70

5 Appendix...................................................................................................................... 97

6 References.................................................................................................................. 122

1

1 Introduction

1.1 General Hydrocarbons serve as the ultimate resource for organic chemicals.1,2 They are the major

constituents of natural gas and petroleum, but there are few processes for converting them directly to

more valuable products.2b Alkanes react at high temperatures, as encountered in combustion, but such

reactions are not readily controllable and usually proceed to the thermodynamically stable and

undesirable products, water and CO2. Although cracking and thermal dehydrogenation convert

alkanes to valuable olefins,3,4 these processes require high temperature and are energy intensive.

Because it is difficult to achieve selective transformations under forcing conditions, the most

important petrochemicals, especially oxygenates such as alcohols, aldehydes and carboxylic acids,

are produced from unsaturated hydrocarbons which in turn are obtained from alkanes by fairly

inefficient processes. Milder and better-controlled direct conversions of alkanes into olefins may thus

offer large economic benefits. Moreover, selective functionalisation of hydrocarbons is one of the

central goals in chemistry since it may lead to utilization of readily available, cheap chemical

feedstocks.

In general, reactions can be catalyzed both heterogeneously and homogeneously. Most industrial

processes are catalyzed heterogeneously. However, they are usually performed at high temperatures

and pressures (vide supra) and are less selective. Homogeneous catalysis has advantages in

selectivity, milder reaction conditions and economy in reagents. There are number of industrial

processes which use homogeneous catalysts; hydroformylation, hydrocyanation (adiponitrile), alkene

polymerization, methanol carbonylation etc.5 In recent years stereospecific syntheses are beginning

to have a major impact on the pharmaceutical industry with products like L-dopa.6 The activation of

strong C-H bonds of hydrocarbons is a crucial step in the overall process of funcionalization of such

compounds. Thus, addition of C-H bonds to transition metal centers is clearly of great interest in this

context (vide supra).7 Studies of systems that undergo observable C-H additions have yielded deep

insight into this reaction over the past two decades,8 however, there is for the most part a disparity

between such systems and those that effect catalytic conversions. Usually, metal based systems

capable of C-H activation result in saturated stable six-coordinated complexes. The lack of a free

coordination site makes them not applicable as catalytic systems for hydrocarbons functionalization.

Therefore, the search for organometallic complexes which can lead to unsaturated speciess after C-H

bond activation is highly desirable. Many examples of C-H bond activation under relatively mild

conditions by transition metal complexes are known2 and several mechanistic comprehensive studies

of this process have been reported.9 Such studies are important for the design of efficient processes

for the functionalization of hydrocarbons. There are five major processes in which a C-H bond can be

cleaved; oxidative addition, sigma-bond metathesis, metalloradical activation, 1,2-addition and

electrophilic activation. We are going to deal with the two most common processes, oxidative

addition and sigma-bond metathesis.

1.2 Oxidative Addition

The oxidative addition process is typical for electron-rich, low-valent complexes of the late transition

metals like, rhodium, iridium, platinum, ruthenium and osmium. In this reaction type the reactive,

coordinatively unsaturated, unstable speciess can be generated in situ from a saturated complex by

thermal or photochemical decomposition (Scheme 1).

LnM(m) LnM(m+2)A-B+

A

B

Δ or hυLn-1M(m)

Scheme 1

The actual process involves bond cleavage of the reactant followed by concomitant formation of two

metal- ligand (anionic) bonds and the formal oxidation state of the metal increases by two units. This

process is governed by the following factors. 1. Electron density on the metal center; the higher the

electron density on the metal the more reactive it is, both kinetically (increased nucleophilicity and

stabilization of intermediates adducts, formed prior to bond cleavage, such as η2C-C or η2C-H) and

thermodynamically, by the stabilization of higher oxidation states. Electron density on the metal is

increased by basic and/or nucleophilic ligands (good σ-donors) and reduced by strong π-acids ligands

or/and when the complex overall charge is positive. 2. The more negative the enthalpy is, (∆Htot=

(BDEM-R+BDEM-X)-BDEX-R ; R=H, alkyl; X=S, O, Si, Br..) the more favorable is the oxidative

addition of the bond; overall gain in bond strength. For example, Si-H > C-H, S-H > O-H, Me-I >

Me-Br > Me-Cl etc'. Moreover, orbital directionality can have an important kinetic effect on

oxidative addition. For example, the H-H bond (1s-1s orbitals) will be cleaved faster than C-H (1s-

1sp3) bond, because of the necessity to direct the sp3 orbitals found in a C-H bond.10 3. Coordinative

saturation of a metal center inhibits the oxidative addition; It is known that coordinatively

unsaturated intermediates are the active speciess in the process of oxidative addition. In some cases

even in non-saturated low valent 16e complexes ligand dissociation is crucial for oxidative addition,

especially of C-H bonds. 4. The steric environment around the metal is crucial for the coordination of

the substrate to be cleaved; the higher the hindrance, the lower the reactivity.

There are a few mechanisms by which oxidative addition can take place, two of which are relevant

to our work. In the first, a mechanism involving a asymmetric three centered transition state (Scheme

2). There is no charge separation in this process. Usually H-H, C-H, Si-H and C-C bonds are cleaved

via this mechanism.11 The mechanism begins with formation of a σ adduct of the bond to be cleaved

with the metal. Electron donation from the metal to the σ* orbital of this bond leads to bond

2

cleavage.12 The second mechanism involves nucleophilic attack on one of the atoms comprising the

bond to be cleaved (like in MeI). In this reaction profile, charge separation is developed, hence

polarized bonds such as H-X, C-X (X=halide) are normally activated via this mechanism.13

LnM(m)

LnM(m+2)

+

Y

Ln-1M(m)

X= Halide Y= H or alkyl

X-XOr

X-Y

X

Y +X

LnM(m+2)

Y

X

Ln(m+2)M

YLn-1M(m)

XY

X

SN1

SN2

Scheme 2

1.3 Sigma-Bond Metathesis

This process is the interchange of alkyl fragments between metal alkyl and H-alkyl group. It is

most common with early transition metal with d0 electronic configurations, however, some late

transition metals exhibit such reactivity especially at high oxidation states (Scheme 3).

LnM-R + H-R' LnM-R

H R'

LnM-R

R' HOr

LnM-H

LnM-R'

Or

+

+

R-R'

H-R

Scheme 3

In the process of functionalizing hydrocarbons obviously the C-H bond activation is a crucial step,

however, many other processes are involved in the actual functionalization. Such processes include

β-H elimination, α-H elimination, reductive elimination, migratory insertion of an alkyl or hydride

group to an adjacent unsaturated ligand (the reversal of β-H elimination), etc.

1.4 Migratory Insertion/ β-H Elimination.

Migratory insertion and its reverse process, β-H elimination are very important steps in

hydrogenation or dehydrogenation, in hydroformylation, polymerization processes, decarbonylation

of aldehydes and many other important catalytic reactions (Scheme 4).14 Migratory insertion enables

the combination and transformation of ligands (CO, olefins etc') within the coordination sphere of the 3

metal. There are few important factors governing the migration; one is the relative position of the

inserted ligand and the migrating one, both of them should be in cisoidal orientation. Another factor

is steric; in general increased steric hindrance around the metal (bulky auxiliary ligands or bulky

migrating group) favors the migration. Decreasing the electron density on the metal will favor

migration because back-donation to the unsaturated ligand (CO, olefin) will decrease as well

rendering the ligand to be more prone to nucleophilic attack. In addition increased nucleophilicity of

the migrating ligand will increase reactivity (alkyl> aryl). Examples of alkyl, aryl, hydroxo and

alkoxo ligands migrating to CO are often observed, while directly observed migration to olefins is

more rare. On the other hand, hydride and acyl ligands are rarely observed to migrate to CO, while

migratory insertion to olefins is more common. The reverse process β-H elimination is the crucial

step in the dehydrogenation of alkanes, alcohols and other saturated compound to produce olefins,

ketones or aldehydes etc. An example of a process where all these steps are involved is the

hydroarylation of olefins. For example, insertion of ethylene into the C-H bond of benzene to form

styrene (Scheme 4). Oxidative addition of benzene is the first crucial step, a vacant site for

coordination of ethylene is necessary prior to insertion. Ethylene coordination can be followed by

hydride migration to the bound ethylene, however, this is a reversible step. Thus, phenyl migration

into ethylene is the second crucial step, which can be followed by C-H reductive elimination to form

ethylbenzene(while regenerating the catalyst), or β-H elimination to form styrene and metal

dihydride (Scheme 4).

LnM

R'

H

RCO

Or+

LnM

R'

H

R

LnM

R'

R

R'R

Migratory Insertion

β−H elimination

C−Η reductive elimination

β− H Elimination

LnM

H

R'

R

LnM

H

R

R'H

LnM

H

H

H2

R

R'HH

Scheme 4

4

1.5 α-H Elimination

α-H elimination is actually a de-insertion reaction where a proton from an alkyl group, which is

bound to the metal, migrates to the metal to form, formally, a metal carbon double bond. Such

speciess are named metal carbenes. In the last decades it is one of the most prominent class of

transition metal organometallics. The metal alkyl- alkylidene functionalities are related by the

generalized equilibrium represented in scheme 5.

LnM

R

HLnM

R

H

LnM

R

HLnM

R

H

O

OFischer-Type Carbene

Schrock Carbene

Scheme 5

For a given metal, several factors have been identified that may shift the equilibrium to the right. 1.

The use of a strongly basic alkyl leaving group and 2. A sterically congested metal environment, both

for protecting the carbene from decomposition (mostly dimerization) and for inducing the leaving

group to depart. For example, Schrock and co-workers have made extensive use of this approach to

induce intramolecular α-H abstraction from an alkyl to an alkylidene complex.15 However, when both

α and β hydrogens are present in a sterically hindered environments α-H elimination may be faster

than β-H elimination.

1.6 The Choice of a Ligand: Pincer Type Ligands

During the last decades since Shaw and co-workers,16 the chemistry of transition metal complexes

containing tridentate bis-chelating phosphines and amines, has become an important area in

organometallic chemistry (Figure 1).17 Pincer type ligands have several advantages; they increase the

stability of metal complexes, their synthesis is easy and it is possible to prepare a non-symmetrical

pincer ligands and control the electronic and steric environment of the metal relatively easy.

Moreover, they confer a rigid framework and frequently seem to impose unusual reaction

pathways.18 Furthermore, the high interest is due to the wide application of these complexes both in

various catalytic processes and in numerous stoichiometric19 chemical transformations relevant to

organic synthesis.20 For example, recently, catalytic conversion of alkanes to alkenes, was reported8

using a catalyst based on the rigid PCP type Ir system (Scheme 6).21 Moreover, our group has

reported on PNN based ruthenium complexes that can dehydrogenate alcohols or couple alcohols to

esters and more recently a remarkable coupling of alcohols and primary amines to yield amides was

reported as well.22

5

RR

X

Z

YR

RX= P, S, N, O; Y= N, S, P, O etc'; Z= C, N etc'

R= Alkyl, Aryl, O-Alkyl, O-Aryl etc' Figure 1

Several PNP-based late transition metal complexes have been reported,23 while related Ir complexes

are scarce. To our knowledge only one example of PNP-Ir complex has been reported.23a However, in

most systems reported to date the phosphine donors bear phenyl substituents. In recent years, anionic

PNP type ligands (where the N moiety is an amide N-) and their complexes were synthesized. In

2002 we have shown the capability of these PNP based Ir complexes to activate vinylic C-H bonds.

A year later we have synthesized the novel cationic, 16e, d8 (PNP)Ir(I)COE complex which exhibited

high reactivity toward aromatic C-H bonds, producing the first stable penta-coordinated hydrideo

phenyl complex. Moreover, remarkable selective C-H bond activation of haloarenes at the most

sterically hindered ortho- position was demonstrated. This kind of novel interesting reactivity had

encouraged us to continue studying the C-H bond activation of other substrates. In addition, we have

synthesized two additional kinds of neutral phosphines based ligands, a PNP ligand where the

phosphines bear less bulky iso-propyl substituents, and a hemi-labile PNN ligand. Both iridium and

rhodium complexes based on these ligands, have been studied.

PtBu2

PtBu2

IrH

H

150oC Scheme 6

1.7 Aromatic C-H Bond Activation

Thus far, we have emphasized the importance of functionalization of hydrocarbons and dealt with

few important processes which are crucial steps towards achieving this goal. Among the feedstocks

that are found in petroleum and produced from it are aromatic arene compounds such as benzene,

toluene etc. The catalytic functionalization of aromatic C-H bonds is of considerable interest for

chemical and pharmaceutical industries, and remains a long-term challenge to chemists.24 It would

6

7

provide simple, clean and economic methods for making aryl-substituted compounds directly from

simple arenes since no prefunctionalization such as halogenation is involved. Relatively few catalytic

systems that are synthetically practical are known while there are many examples of stoichiometric

aryl C-H bond activation by transition metal compounds.25

One example of such a catalytic process is the ortho arylation of aromatic ketons catalyzed by low

valent Ru complexes.26 In most cases, the direct use of aromatic compounds in synthesis relies on

the presence of a more reactive group than C-H bond. For example, it is common to employ

activation of the C-X (X= Cl, Br, or I) bond of aryl halides to transfer aryl groups.

Examples for such a reaction are the Heck reactions27 or cross-coupling reactions between aryl

halides and nucleophiles. The arylation of olefins (Heck reaction) is indeed a key reaction for

construction of new C-C bonds. Despite being compatible with most functional groups and thus,

attractive for the production of fine chemical, a major drawback accompanying this procedure is the

restriction to mainly organic halides as substrates which are less economical than hydrocarbons and

produce a significant amount of salt waste. Fujiwara and later others reported the Pd-catalyzed

oxidative coupling of arenes and olefins.28 In these cases, the presence of peroxides was needed in

combination with strong acids and/or elevated temperatures, which are significant industrial

drawbacks. Recently, our group reported the use of high valent Ru catalysts and O2 as oxidant,

producing only water as side product.29 However, the reaction requires high temperatures and is not

regioselective. An attractive goal is the selective C-H bond activation of substituted arenes or

alkanes. Murai et al. reported the regioselective catalytic ortho-hydroarylation of aromatic esters,

ketones and aldehydes based on metal coordination to the carbonyl group.25d,e Amine, pyridyl,24h

hydroxy24i and or other good coordinating groups have also been utilized. Recently, selective ortho-

C-H bond activation of acetophenone and nitrobenzene by an electron rich (PCP)Ir complex was

reported.24a,b It was shown in this case that the selectivity is governed by thermodynamics rather than

kinetics, i.e. stabilization of the C-H activation product by coordination of the ortho functional group

to the metal, while coordination prior to C-H activation does not play a significant role. The chemo-

and regio-selective activation of strong C-H bonds in the presence of substitutionally reactive groups,

such as halo-substituents, is intriguing fundamentally and of potential synthetic importance. There

are a few reports of C-H bond activation of hydrocarbons in the presence of a C-Cl bond,30,31 and in

most cases such chemo-selectivity was demonstrated with systems in which oxidative addition is

difficult, such as late transition metal complexes of Ir, Rh having low electron density at the metal, or

early transition metals, where the mechanism probably involves σ- bond metathesis. Moreover,

coordination of halo-arenes to metal centers through the halide substituent is known to stabilize

electron poor, high-valent transition metal speciess.

32 Although examples of C-H activation of

haloarenes by soluble late-transition metal complexes were reported, activation of the less

hindered meta- and para- C-H bonds was observed due to steric reasons. Selective ortho C-H

24, 33

8

activation of fluoroarenes is known.34,35 Recently, selective ortho-C-H bond activation of

chlorobenzene by a Zr complex was reported and competitive C-Cl and ortho- C-H bond activation

of chlorobenzene in the gas phase by FeO is known. We have reported on an electron-rich, cationic

PNP-type Ir(I) system which undergoes facile arene C-H bond activation, leading to unsaturated,

stable arene-Ir(III) hydride complexes. This system exhibits chemo- and regio-selectivity towards

ortho-C-H bond activation in chloro- and bromobenzene. No C-halide oxidative addition was

observed. The process was suggested to be directed by coordination of the metal to the halide

substituents. Detailed calculations in search of the origin of regio- and chemo- selectivity were

reported by us in Organometallics. (See: Appendix)

36

+

37

36

1.8 Fischer-Type Carbenes

The use in organic synthesis of complexes of the type (L)5M=C(X)R (M= Cr,Mo, W ; X= hetero

atom and R= a saturated alkyl or unsaturated alkenyl, alkynyl or ary group), which are known as

Fischer carbene complexes after their discoverer,38 is relatively recent and has already produced

impressive synthetic results.39 These versatile organometallic reagents have an extensive chemistry

and they are probably one of the few systems that undergo cycloadditions of almost any kind. One of

the reasons for the reactivity of Fischer carbenes is the elecrophilic character of the carbene carbon,

making this carbon susceptible to nucleophilic attack. This process is very useful for conversion of

methoxycarbene complexes to a wide variety of differently substituted carbene complexes,

particularly those containing heteroatoms other than oxygen. However, the most intense investigation

has been focused on carbene complexes of metals in groups 5-7, while less is known about the

reactivity of carbene complexes of groups 8-10, though these late-metal carbene complexes have

been implicated as reactive intermediates in several catalytic processes. This apparent lack of study is

perhaps due to the small number of rational synthetic methods available to generate these complexes.

Therefore, selective C-H bond activation under mild conditions, to form carbene complexes of

groups 8-10 is a desirable process. In the last decade or so several articles were published on the late-

transition metals carbenes, especially Ir based carbene complexes. These carbenes are prepared by

simple double C-H bond activation of ethers and amines. Heteroatom (N- or O-) coordination to an

unsaturated Ir(III) center facilitates metal attack to the adjacent C-H bonds, whereas the formation of

sufficiently strong C-H bonds with sacrificial alkyl or aryl leaving groups provides the

thermodynamic driving force needed for the formation of metal-carbene linkage.40 Examples of

double C-H bond activation of ethers by ruthenium is also known and it proceeds through dimeric

interaction to form a Ru carbene and Ru hydrideo dihydrogen complex.41 Other work includes

chelation-assisted carbene formation of an Ir complex.42

9

1.9 Hydrocarbons Oxidation by Molecular Oxygen

Molecular oxygen is a highly desirable oxidant from chemical, environmental and economic

standpoints.43 In classical organic chemistry, organic substrates are oxidized with inorganic oxidizing

reagents like chromium and manganese oxides, halogens and nitric acid. Only rarely has molecular

oxygen been used. Free radical aoutooxidation is non-selective and used with a limited number of

relatively simple substrates.44 Thus, there is a great need for catalytic methods that can compete with

radical outooxidation in liquid phase. Moreover, the traditional methods are environmentally

unacceptable and are being replaced by cleaner oxidation methods.

It is apparent that selective transformation of hydrocarbons, especially saturated ones, to valuable

oxygenates is an extremely important area of contemporary industrial chemistry, particularly the

selective oxidation by molecular oxygen. Fundamental studies of the role of transition metals in

catalytic oxidation must naturally include investigations of the reaction pathways of organometallic

molecules with O2. Bearing in mind that activation of hydrocarbons involves the formation of metal

alkyl hydrides, M(H)(R), the insertion of O2 into M-C or M-H bonds is of central importance.

Examples of O2 insertion into M-H bonds were recently reported by Goldberg, who studied the

insertion of oxygen into Pd-H or Pt-H45 bonds and found that formation of Pd-OOH involves a non-

radical insertion. The activation of oxygen by low-valent Ir and Rh complexes is known. Moreover,

cyclohexane oxidation in the presence of low-valent complexes of Ir, Rh and Pd was reported. The

mechanism involves most probably activation of oxygen to produce a peroxo intermediate. However,

the insertion of molecular oxygen into Ir-H or Rh-H is rare. In chapter 2.6 we describe the overall

insertion of O2 into Ir-H and Rh-H via a non-radical reaction mechanism.

10

2 Research Objectives

1. Synthesis of new cationic and neutral PNP based Ir and Rh complexes (iPrPNP = 2,6-bis(di- iso-

propylphosphinomethylene)pyridine, tBuPNP = 2,6-bis(di tertButylphosphinomethylene)pyridine).

2. Fundamental study of their reactivity toward strong bonds, mainly aromatic and aliphatic C-H

bonds, and toward H2 and O2.

3 Results and Discussion

3.1 Ortho C-H Activation of Haloarenes and Anisole by

An Electron Rich Ir(I) Complex.

Mechanism and Origin of Regio- and Chemo-Selectivity.

An Experimental and Theoretical Study.

The electron rich, cationic, Ir(I) complex 146 was prepared by addition of an equimolar amount of the

PNP ligand (Scheme 7) to a yellow solution of the cationic complex [Ir(I)(acetone)2(COE)2]+PF6 47 in

acetone, resulting in a color change to red-purple. 31P{1H} NMR revealed an AB quartet system at 46

ppm, indicative of a low-symmetry complex due to the sterically demanding environment around the

metal center. Purple-red prismatic crystals of 1 were obtained by slow evaporation of its acetone

solution. An X-ray crystallographic study revealed a distorted square planar geometry48 (Fig. 2, Table

1). Reaction of [Ir(COE)2Cl]2 with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArF) in

acetone followed by addition of 2 equiv of the PNP ligand resulted in formation of complex

(PNP)Ir(COE)+BArF- in 80% yield (Scheme 7).

N

PtBu2

PtBu2

Ir

+ X-

Ir(COE)2(Acetone)2+X-

X-= PF6-, BArf-

PNPAcetone

1X-= PF6-

X-=BArf- 1a Scheme 7

The unique reactivity of these complexes towards C-H activation of benzene, haloarenes and anisole

were experimentally and theoretically investigated. Both complex 1 and complex 1a were investigated

and the same reactivity was observed.

11

Figure 2: POV- Ray drawing of 1 at 50% probability level.

Hydrogen atoms and counter-anion are omitted for clarity.

For selected bond lengths and angles see Table 1.

Table 1:Selected bond lengths [Å] and angles [o] of 1

Selected bond Bond lengths (Å) Ir(1)- P(1) 2.3376(15) Ir(1)- P(2) 2.3370(13) Ir(1)- N(1) 2.103(5)

Selected bond Bond angles [deg] N(1)- Ir(1)- P(1) 79.84(4) N(1)- Ir(1)- P(2) 90.2(4) C(6)- Ir(1)-P(1) 85.6(3) C(7)- Ir(1)-P(1) 94.3(4) C(6)- Ir(1)-P(2) 94.4(4) C(7)- Ir(1)-P(2) 85.5(6)

12

3.1.1 Reaction of (tBuPNP)Ir(COE)+ With Benzene

Heating of complex 1 at 50 oC for 1 hr (or at 25 oC for 48 hrs) in benzene resulted in formation of the

unsaturated aryl hydride complex 2 (Scheme 8). 31P NMR of this complex revealed a doublet at 54

ppm with 2JHP= 13 Hz, characteristic of cis- hydrogen-phosphorous coupling. 1H NMR exhibited a

triplet at -44 ppm, indicative of a hydride located trans to a vacant coordination site. Orange prismatic

crystals were obtained by slow evaporation of a benzene solution of 2. Single crystal X-ray analysis

revealed a slightly distorted square pyramidal geometry around the metal center, the hydride being

located at the axial site (Fig. 3, Table 2). 49

N

PtBu2

PtBu2

Ir

+ PF6-

N

PtBu2

PtBu2

Ir

+ PF6-

N

PtBu2

PtBu2

Ir

+ PF6-

HH

m-Xylene

1 hr, 50 oC

Benzene

1 hr, 50 oC

3 1 2

Scheme 8

Although complex 2 is coordinatively unsaturated, it exhibited high stability, showing no decomposition

upon heating as a solid at 100 oC for 24 hrs. However, when heated at 60 oC in m-xylene, arene exchange

took place, resulting in the m-xylyl complex 3 (Scheme 9), which was synthesized independently by

heating of 1 in m-xylene at 60 oC (Scheme 8). Furthermore, when complex 2 was heated at 60 oC in C6D6,

disappearance of the hydride ligand and appearance of a deuteride was observed, indicating formation of

(tBuPNP)Ir(D)(C6D5), 2a.

N

PtBu2

PtBu2

Ir

+ PF6-

N

PtBu2

PtBu2

Ir

+ PF6-

DH

m-Xylene

60 oC

Benzene d6

60 oC

3 2a

N

PtBu2

PtBu2

Ir

+ PF6-

H2

Scheme 9

Complex 2 represents a rare example of a thermally stable coordinatively unsaturated M(III) d6

hydrideo- aryl complex. Such speciess are proposed as reactive intermediates in several transition

metal catalyzed processes.50,26 Werner reported the only example of a crystallographically

characterized, thermally stable, unsaturated Ir(H)(R) ( R=aryl, alkyl) complex,

Ir(PiPr3)2(H)(C6H5)(Cl).51 Recently, Goldman reported a closely related unsaturated complex

(PCP)Ir(H)(C6H5) (PCP = 2,6(tBu2PCH2)2C6H3).21

13

14

Figure 3: POV-Ray drawing of 2 at 50% probability level.



Table 2: Selected bond lengths [Å] and angles [o] of 2

Bond lengths (Å) Selected bond 2.3143(15)

Ir(1)- P(3)

2.3230(13) Ir(1)- P(2) Ir(1)- N(5)

Ir(1)- C(1) 2.142(5) 2.043(7)

1.66(7) Ir(1)- H(1) Bond angles [deg] Selected bond

82.64(14) N(5)- Ir(1)- P(2) 79.84(4) N(5)- Ir(1)- P(3)

97.15(18) C(1)- Ir(1)-P(3) 89(3) H(1)- Ir(1)-P(3) 88(2) C(1)- Ir(1)-H(1) 165.99(7) P(3)- Ir(1)-P(2)

This thermally unstable complex was characterized in solution and exhibited fast arene exchange even

at low temperature, which followed a dissociative mechanism. Intuitively, it seems that the main

difference between these isoelectronic systems is the electron density at the iridium centers. Since a

lower electron density is expected at the iridium center of the cationic (tBuPNP)Ir system, which

should result in more facile reductive elimination and lower thermal stability, the observed higher

stability of the PNP system is surprising. It could be argued that a reductive addition process52 took

place, increasing the electron density on the (tBuPNP)Ir system after addition of the C-H bond. In

order to address the question of relative electronic density on the cationic Ir(I) and Ir(III) PNP-based

systems (and to compare it to the relevant PCP-based neutral Ir complex), the corresponding carbonyl

complexes were prepared. Addition of one equivalent of CO to a DMSO solution of (PNP)Ir(H)(C6H5)

2 resulted in formation of (PNP)Ir(H)(C6H5)(CO) 4 (The 31P{1H} NMR spectrum of 4 revealed a

signal at 45 ppm and 1H NMR exhibited the hydride ligand as a triplet at -7.5 ppm, representing a large

downfield shift compared to the corresponding hydride signal of complex 2 (-44 ppm). Such a shift

indicates coordination of the CO trans to the hydride ligand. In addition, 13C{1H} NMR revealed a

characteristic signal at 183 ppm for the Ir-CO bond. A comparison of the CO absorption frequency of

(PCP)Ir(CO)(H)(C6H5)7 (1973 cm-1) with that of (tBuPNP)Ir(H)(C6H5)(CO) 4 (2005 cm-1) indicates

that the electron density at the cationic Ir(III) center in 4 is lower, as expected. Moreover, the CO

stretching frequency of (tBuPNP)Ir(CO) 5 (1964 cm-1) and 4 (2005 cm-1) indicate a significantly lower

electron density on the Ir(III) center of 4. This indicates that C-H oxidative addition rather than

reductive addition took place. Complex 5 was prepared by the facile reaction of complex 1 with one

equiv of CO (Scheme 10).

N

PtBu2

PtBu2

Ir

+ PF6-

H2

N

PtBu2

PtBu2

Ir

+ PF6-

H4

CON

PtBu2

PtBu2

Ir

+ PF6-

5

CO

N

PtBu2

PtBu2

Ir

+ PF6-

1

CO

CO

Anisole110oC; 48 hrs

Scheme 10

Interestingly, elimination of benzene from complex 4 occurred only when it was heated to a

temperature as high as 110 oC for 48 hrs, resulting in quantitative formation of (tBuPNP)Ir(CO) 5

(Scheme 10). The octahedral (tBuPNP)Ir(H)(C6H5)(CO) 4, like Goldman’s (PCP)Ir(H)(C6H5)(CO), is

kinetically stabilized towards reductive elimination of benzene, which is expected to involve ligand

loss.53 Complex 5 did not exhibit C-H oxidative addition reactivity, as no reaction took place when it

was heated in anisole at 110 oC. Noteworthy, addition of acetonitrile to complex 2 resulted in the

formation of complex 6, which was crystallographically characterized, exhibiting an octahedral

structure with the nitrile ligand coordinated trans to the hydride ligand in an end-on fashion (Fig. 4,

Table 3). A comparison of the C-N triple bond length of free acetonitrile (1.158 Å)54 with the C(22)-

N(2) bond length of 1.134 Å, indicates that there is practically no back donation from the metal to the

nitrile group. Complex 6 does not eliminate benzene upon heating in C6D6 even at 70 oC. However, at

higher temperature it exhibits arene exchange (Scheme 11).

15

N

PtBu2

PtBu2

Ir

+ PF6-

H2

CH3CN

1 eq.N

PtBu2

PtBu2

Ir

+ PF6-

H6

NCHCH3 Benzene d6

85 oC; 48 hrsN

PtBu2

PtBu2

Ir

+ PF6-

D6a

NCHCH3 D

Scheme 11

16




Table 3: Selected bond lengths [Å] and bond angles [o] for 6

Bond length [Å] Selected bond 2.072(2) Ir(1)- C(1) 2.3291(9) Ir(1)- P(1) 2.3304(9) Ir(1)- P(2) 2.153(2) Ir(1)- N(1) 2.157(2) Ir(1)- N(2) 1.134(1) C(22)-N(2) 1.46(2) C(22)-C(23) Bond angle [o] Selected bonds 97.78(6) N(1)- Ir(1)- P(1) 95.83(3) N(2)- Ir(1)- C(1) 178.11(8) N(1)- Ir(1)- C(1) 82.44(9) N(1)- Ir(1)- N(2) 178.5(3) N(2)- C(22)-C(23) 98.25(7) C(1)- Ir(1)- P(2)

The kinetic isotope effect of the benzene C-H activation process was determined by dissolving

(tBuPNP)Ir(COE)+PF6 1 in a 1:1 molar ratio of C6H6 : C6D6 and leaving the solution for 48 hrs at 25 oC

under kinetic control, resulting in a kH/kD = 1.0. This observation supports a mechanism where the

actual C-H cleavage occurs after the rate determining step. According to DFT calculations (vide infra),

the reaction pathway involves an early transition state where the rate determining step is dissociation

of the cyclooctene ligand to form a 14e (PNP)Ir intermediate. Conversion of an η2 C-C benzene

complex to an agostic η2

C-H complex involves the second highest barrier, followed by the C-H cleavage

step (vide-infra).

3.1.2 Reaction of (PNP)Ir(COE)+ 1 With Aryl Halides

When complex 1 was heated in fluorobenzene at 60 oC for 1 hr, three regioisomers of

(tBuPNP)Ir(H)(C6H4F)+PF6 7 were formed. 31P{1H} NMR revealed signals at 55.2 ppm, 58 ppm and

52.3 ppm in a ratio of 2:2:1, assigned to 7a, 7b and 7c, respectively (vide-infra). 1H NMR revealed

three signals in the hydride region in the same ratio at -41, -45 and -42.5 ppm, respectively. An NOE

experiment was carried out on a mixture of ortho-and para- isomers (obtained as described below), in

order to assign the observed hydrides and the ortho- aryl proton resonances to isomers 7a and 7c.

Irradiation of the signal at -41 ppm resulted in NOE enhancement of a signal at 7.10 ppm, while

irradiation of the signal at -42.5 ppm gave NOE enhancement of the signal at 7.25 ppm corresponding

to two protons. Together with H-H correlation spectroscopy (COSY), the signals at -41, -45 and -42.5

ppm were assigned as the ortho-, meta- and para-C-H activated fluorobenzene complexes 7a, 7b and

7c, respectively. Thus, the C-H activation process of fluorobenzene is not selective. Prolonged heating

for 48 hrs at 60 oC resulted in a mixture of the ortho-activated and the para-activated fluorobenzene

complexes 7a and 7c in ratio of 1.8:1 respectively. Heating at 70 oC or higher for 48 hrs resulted in a

similar mixture of o- and p- isomers in a ratio of 2.3:1, respectively (Scheme 12).

N

PtBu2

PtBu2

Ir

+ PF6-

H

Complex 1 Fluorobenzene 60 oC, 1 hr

F

7a : 7b : 7c

o- m- p-

2 : 2 : 1

N

PtBu2

PtBu2

Ir

+ PF6-

H

F

7a : 7b o- p-

1.8 : 1

2.3 : 1

Fluorobenzene

60 oC ; 48hrs

70 oC ; 48hrs Scheme 12

17

Selective C-H activation of fluorobenzene at the ortho position was reported and was studied

theoretically as well as experimentally.35, ,55 34 The ortho isomer was shown to be the

thermodynamically most stable one in the case of a Re33a complex, kinetically and thermodynamically

in the case of Os.33b Moreover, it is known that the ortho-positions in haloarenes are the most acidic

ones, especially in fluoroarenes.56a While complex 1 exhibited no kinetic preference, and low

thermodynamic preference, for the ortho-C-H bond of fluorobenzene, ortho-C-H selectivity was

observed with chlorobenzene. Thus, heating complex 1 in chlorobenzene at 50 oC for 1 hr resulted in

the o-, m-and p-isomers of (tBuPNP)Ir(H)(C6H4Cl) complexes in a ratio of 4.6:2:1, assigned as 8a-c,

respectively (vide-infra), at a point where 1 was fully consumed (Scheme 13). 31P{1H} NMR revealed

a signal at 51 ppm due to the ortho-isomer and a broad signal at 54 ppm corresponding to the meta-and

para-isomers. 1H NMR revealed a hydride signal at -34 ppm, which is characteristic of M-H trans to

an occupied coordination site (ortho-isomer, see below), and at -41 and -44 ppm for the meta- and

para- isomers. Irradiating the hydride signal in 1H NMR at -41 ppm gave an NOE enhancement

(relative to the aryl protons) at 7.35 ppm. Irradiating the signal at -44 ppm resulted in an NOE

enhancement of the aryl protons at 7.45 ppm. Together with COSY data, the signals at -41 ppm and -

44 ppm were assigned to the hydride ligands of the meta- and para- C-H activated chlorobenzene

complexes 8b and 8c, respectively. Monitoring the reaction by NMR revealed at 10% conversion a

ratio 8a:8b:8c of 4:2:1, indicating that complex 1 has a kinetic preference for the activation of the C-H

bond ortho to the chlorine atom. Remarkably, when this reaction mixture was heated for 48 hrs,

complex 1 was totally consumed and complexes 8b and 8c were fully converted to the ortho-activated

complex 8a (Scheme 13), indicating that this complex is the most kinetically and thermodynamically

favored product under these conditions.

N

PtBu2

PtBu2

Ir

+ PF6-

1

N

PtBu2

PtBu2

Ir

+ PF6-

H

8a : 8b : 8co- m- p-4.6 : 2 : 1

ClChlorobenzene

50 oC; 1 hrN

PtBu2

PtBu2

Ir

+ PF6-

H

Chlorobenzene

50oC 48 hrs

Cl

8a

Scheme 13

Yellow prismatic crystals were obtained by slow diffusion of pentane into a chlorobenzene solution

of complex 8a. An X-ray analysis of 8a reveals that the Ir atom is located in the center of a distorted

octahedron57b (Table 4, Fig. 5) The chlorine atom is coordinated to the metal and, as predicted from

the NMR data, it is located trans to the hydride. Although the Ir-Cl bond length of 2.816 Å is

significantly shorter than the sum of the van der Waals radii of Ir and Cl atoms, it is longer than other

reported Ir-Cl bonds in coordinated chloroalkanes.31c This elongation is probably due to some strain in

18

the four-membered ring, as indicated by the Ir-Cl-C angle of 72o. Noteworthy, the C-Cl bond (1.78 Å)

is significantly elongated compared to the one in free C6H5Cl (1.700 Å), suggesting π-back-donation

from a filled metal d-orbital to the empty C-Cl π*-orbital. Interestingly, complex 8a is the most stable

isomer despite the steric hindrance imposed by the chlorine atom. The intramolecular coordination of

the Cl atom of activated chlorobenzene can explain the higher thermodynamic stability of 8a versus

the other isomers 8b and 8c, in which such coordination is obviously impossible. Halocarbon

coordination to transition metals is well documented,31,57 although examples of chloro- and

bromoarene coordination are not common.58 Remarkably, reaction of 1 with bromobenzene is similar

to that of chlorobenezene, despite the higher steric hindrance imposed by the Br atom and the expected

high reactivity of Ar-Br towards oxidative addition to electron rich Ir(I) (Scheme 14).

N

PtBu2

PtBu2

Ir

+ PF6-

1

N

PtBu2

PtBu2

Ir

+ PF6-

H

9a : 9b : 9co- m- p-7 : 2 : 1

BrBromobenzene

50oC 1hrN

PtBu2

PtBu2

Ir

+ PF6-

H

Bromobenzene

50oC 48 hrs

Br

9a

Scheme 14

In a 31P{1H} NMR follow-up experiment at 50 oC, a signal corresponding to the ortho- C-H activation

complex 9a was observed at 49 ppm, in addition to a broad signal at 51-51.5 ppm, corresponding to

the m-and p- activated complexes 9b,c. 1H NMR revealed three hydride signals at -29, -42 and -45

ppm, corresponding to the ortho-, meta- and para isomers in a ratio of 7:2:1, respectively, at 10%

conversion. Irradiating the signal at -42 ppm resulted in NOE enhancement between the hydride and

aryl protons at 7.56 ppm. Irradiating the signal at -45 ppm gave an NOE enhancement between the

hydride and aryl proton at 7.52 ppm. Together with COSY results, the signals at -42 ppm and -45 ppm

were assigned to the hydride ligands of the meta- and para- C-H activated bromobenzene complexes

9b and 9c, respectively. Continued heating at 50 oC for 48 hours resulted in quantitative formation of

9a as the sole product (Scheme 14). These results show that 9a is both kinetically and

thermodynamically favored. Slow diffusion of pentane into acetone solution of 9a resulted in nearly

colorless crystals. X-ray crystallography study revealed that the Ir-Br bond length is 2.78 Å which is

significantly shorter than the sum of van der-waals radii of Ir and Br, contribute to the NMR

observation and support the assumption that Br is coordinated to the metal center (Table 5, Fig. 6).

19

Figure 5: POV-Ray drawing of 8a at 50% probability level.

Hydrogen atoms and counteranion are omitted for clarity.

For bond lengths and angles see Table 4.

Table 4: Selected bond lengths [Å] and bond angles [o] for 8a

Selected bond Bond lengths(Å) Ir(1)- P(1) 2.3363(13) Ir(1)- P(2) 2.3290(12)

2.159(45) 1.782(4)

Ir(1)- N(1) Cl(1)- C(6)

Ir(1)- Cl(1) 2.8161(14) Selected bond Bond angle[deg] N(1)- Ir(1)- P(1) 83.02(10) N(1)- Ir(1)- P(2) 80.94(10) C(1)- Ir(1)-P(2) 98.22(11) C(1)- Ir(1)-P(2) 99.00(11) C(2)- Ir(1)-P(1) 94.4(4)

C(2)- Ir(1)-P(1) 85.5(6)

Cl(1)- Ir(1)-H(1) 167(2)

20

3.1.3 Reaction of (tBuPNP)Ir(COE)+ With Anisole. When 1 was heated in anisole at 50 oC for an hour, the ortho-, meta- and para- C-H activated anisole

complexes 10a-c were formed. Complex 10a was the major product (93% of the resulting mixture).

Continued heating for 24 hours at the same temperature resulted in the sole formation of the ortho-

isomer 10a (Scheme 15). Complex 10a gives rise to a doublet at 56.60 ppm in the 31P{1H} NMR

spectrum and a triplet at -42 ppm in the 1H NMR spectrum. Slow diffusion of pentane into an anisole

solution of 10a resulted in formation of orange prismatic crystals, which were analyzed by X-ray

diffraction (Table 6, Fig. 7). Although there is no indication of strong coordination of the oxygen atom

to the metal center in 10b in solution (only -0.22 ppm shift in the 1H NMR of the OMe group as

compared with anisole), there is an indication for directionality towards the metal center in the solid

state. Thus, the angles C(8)-C(1)-Ir(1), C(2)-C(1)-Ir(1) (131.12o and 112.5o, respectively) indicate

bending toward the vacant site trans to the hydride. This bending is negligible in complex 2, but very

significant in complexes 8a, 9a and 10a. Moreover, the C(2)-O(3) bond length in the crystal structure

(1.397 Å) is longer the Ar-O bond length of free anisole (1.357 Å)31 implying interaction of the

methoxy group with the metal center.

N

PtBu2

PtBu2

Ir

+ PF6-

1

N

PtBu2

PtBu2

Ir

+ PF6-

H

10a : 10b,c o- m-, p-14 : 1

OMeAnisole

50 oC ;1 hrN

PtBu2

PtBu2

Ir

+ PF6-

Anisole50 oC ; 24 hrs

H

10a

O CH3

Scheme 15

21

Figure 6: POV-Ray drawing of 9a at 50% probability level. hydrogen atoms and counteranion are omitted for clarity. For bond lengths and angles see Table 5.


Bond lengths (Å) Selected bond 2.331(4) Ir(1)- P(2) 2.345(4) Ir(1)- P(1)

2.134(15) 2.024(19) 1.94(2) 2.871(2)

Ir(1)- N(1) Ir(1)- C(1) C(6)- Br(1) Ir(1)- Br(1)

Bond angles [deg] Selected bonds 83.0(4) N(1)- Ir(1)- P(2) 80.9(4) N(1)- Ir(1)- P(1) 98.3(5) C(1)- Ir(1)-P(1) 98.8(5) C(1)- Ir(1)-P(2) 67.4(6) C(1)- Ir(1)-Br(1) 69.7(7) C(6)- Br(1)-Ir(1)

22

Figure 7: POV-Ray drawing of 10a at 50% probability level.

hydrogen atoms and counteranion are omitted for clarity.

For bond lengths and angles see Table 6


Bond angle[o] Selected bond Selected bond Bond length [Å] 81.99(10) N(2)-Ir(1)-P(4) Ir(1)-H(1) 1.55(4) 164.04(4) P(4)-Ir(1)-P(3) Ir(1)-C(1) 2.038(4) 90.8(14) P(3)-Ir(1)-H(1) Ir(1)-P(3) 2.3380(13) 96.55(13) C(1)-Ir(1)-P(4) Ir(1)-P(4) 2.3149(13) 83.13(11) N(2)-Ir(1)-P(3) Ir(1)-N(2) 2.139(4) 177.7(17) N(2)-Ir(1)-C(1) C(2)-O(3) 1.397(6) 80.9(14) P(4)-Ir(1)-H(1) O(3)-C(4) 1.425(6) 98.48(13) C(1)-Ir(1)-P(3) O(3)-Ir(1) 2.76(2)

23

3.1.4 Exchange Reactions

In order to compare the regioselective ortho-C-H activation in chlorobenzene, bromobenzene and

anisole we have performed competition experiments under conditions in which there is no exchange

between the ortho-C-H activated complexes 8a, 9a and 10a. When complexes 8a, 9a and 10a were

dissolved, each one separately, in a mixture of anisole and chlorobenzene (1:1 molar ratio) and heated

at 55 oC for 24 hrs, no reaction took place, indicating that the complexes are kinetically stable under

these conditions.

Heating of the Ir(I) complex 1 in a mixture of chlorobenzene, bromobenzene and anisole (1:1:1

molar ratio) at 55 oC for 24 hrs resulted in a mixture of ortho- activated products in a ratio of 38% 10a,

32% 8a and 30% 9a, indicating only a slight preference towards the ortho-C-H bond of anisole as

compared with haloarenes. No Hammett correlation based on these ratios (which correspond to the

relative rates of formation of these complexes) and the σ and the σ+ constants were found, implying

that the overall C-H activation process is not governed by electronic influence. Interestingly, upon

heating the ortho-activated fluorobenzene complex 7a at 55 oC for 1.5 hrs in a mixture of anisole and

chlorobenzene at a molar ratio of 1:1, exchange took place, resulting in a mixture of complexes 8a,

10a, 8b,c and 10b,c, after 45% conversion with respect to 7a. Heating complexes 8a, 9a and 10a

(1:1:1 molar ratios) in a mixture of anisole: chlorobenzene: bromobenzene (molar ratio of 1:1:1) under

thermodynamically controlled conditions, i.e. 70 oC for 5 days,58 a new mixture of the o- isomers was

formed. 31P{1H} NMR revealed three signals at 56, 52 and 49 ppm, corresponding to complexes 10a,

8a and 9a, respectively in 39%, 36%, 25%, respectively (Scheme 16). This implies that the anisole and

chlorobenzene activated complexes 8a and 10a are the most stable thermodynamically, with a slight

preference to the anisole complex 10a.

N

PtBu2

PtBu2

Ir

+ PF6-

H

X

X= Br, Cl, MeO 1 : 1 : 1

N

PtBu2

PtBu2

Ir

+ PF6-

H

X

X= Br, Cl, MeO 23% : 36% : 38%

C6H5OMe: C6H5Cl : C6H5Br

1 : 1: 170oC 5 days

Scheme 16

24

3.2 C-H Vs. H2 Activation by An Electron-Rich PNP Ir(I) System:

(iPr2PNP)Ir(I) vs. (tBu2PNP)Ir(I) .

The electron rich, cationic, Ir(I) complex 11 was prepared, similarly to complex 1, by addition of an

equimolar amount of the iPr2PNP ligand to a yellow solution of the cationic complex

[Ir(I)(acetone)2(COE)2]+PF6 18 in acetone, resulting in a color change to red-purple (Scheme 17).

N

PiPr2

PiPr2

Ir

+ X-

Ir(COE)2(Acetone)2+X-

X-= PF6-, BArF-

PNPAcetone

11 Scheme 17

31P{1H} NMR revealed a singlet 38 ppm, indicative of a symmetric complex (C2v) due to the less

sterically demanding environment around the metal center, relative to complex 1. Purple-red prismatic

crystals of 11 were obtained by slow diffusion of ether into its acetone solution. An X-ray

crystallographic study revealed a slightly distorted square planar geometry (Fig. 8, Table 7). An

elongation of the olefinic (COE) C=C bond (length of 1.4 A) indicates significant back donation from

the metal center to the π* of the COE double bond. 1H NMR revealed a characteristic vinylic signal

corresponding to 2H at 3.90 ppm. 13C{1H} NMR revealed a signal at 51.5 ppm. Interestingly, the

corresponding signals of complex 1 are at 3.60 ppm and 54 ppm, respectively, implying greater back-

donation to the COE π* orbitals in complex 11 than in complex 1. Indeed, when the CO stretching of

complexes 12 and 5 are compared, a negligible difference of 2 cm-1 is observed, implying similar

electron density at both the metal centers of tBu(PNP)IrCO+ 5 and iPr(PNP)IrCO+ 5'. We believe that

the major factor governing this inconsistency is sterics. Although the tBuPNP complex 1 has a similar

electron density (a little bit higher), it has higher steric hindrance, and the orbital overlap between the

COE and the metal is not as good as in complex 11 where the steric hindrance is much lower.

Consequently, back-donation is lower in complex 1.

25

26






2.138(6) 2.137(7) 2.174(7) 1.409(10)

Ir(1)- N(11) Ir(1)- C(1) Ir(1)- C(2) C(1)- C(2)

Bond angles [deg] Selected bonds 81.98(16) N(11)- Ir(1)- P(2) 83.57(16) N(11)- Ir(1)- P(3) 159.3(3) C(1)- Ir(1)-N(11) 161.3(2) C(2)- Ir(1)-N(11) 104.2(2) C(1)- Ir(1)-P(2) 92.4(2) C(1)- Ir(1)-P(3)

100.5(2) 90.5(2)

C(2)- Ir(1)-P(2) C(2)- Ir(1)-P(3)

Surprisingly, when complex 11 was heated in benzene to 70 oC no reaction was observed even after 12

hrs (Scheme 18). We believe that COE dissociation is the impediment for the whole process, where

steric hindrance (and not electron density) is a major factor. However, when complexes 11 and 1 were

reacted with H2, formation of cis-(PNP)Ir(H)(H)+ 12 (Scheme 19) and 13 (Scheme 18) was observed. It

is known that 16e complexes can activate H2 without loss of a ligand, associatively.59 Thus, most

probably, dissociation of COE is not essential for H2 activation. Interestingly, hydrogenation of COE

to cyclooctane was observed only in the reaction between 1 and H2 (Scheme 18). With the aim of

addressing the question of steric versus electronic effects, we have synthesized the less bulky version

of complex 1, tBu2(PNP)Ir(I)(C2H4)+PF6- complex 14 (Scheme 19). When complex 14 was heated in

benzene for 24 hours at 70 oC no reaction was observed. However, similarly to complex 11, when H2

was added, an immediate reaction was observed, to form cis- tBu2(PNP)Ir(III)(H)(H)+PF6- 13 with no

hydrogenation of ethylene (Scheme 19).

H2

1

Ir

13

H

N

PiPr2

PiPr2

Ir

+PF6-

11

No reactionC6H6

70 oC; 12 hrs

N

PtBu2

PtBu2

+PF6-

H

N Ir

+ PF6-

PtBu2

PtBu2

H2N

PiPr2

PiPr2

Ir

+PF6-

12

H

H

Scheme 18

H2 N

PR2

PR2

Ir

R= tBu 13

+PF6-

H

H

N

PtBu2

PtBu2

Ir

+PF6-

14

No reactionC6H6

70 oC; 12 hrs Scheme 19

27

Hydrogenation of olefins proceeds via a few important steps (Scheme 20). Activation of H2,

resulting in a metal dihydride A (usually the cis-dihydride) can take place first, followed by the

formation of a metal dihydride olefin adduct B. Hydride migration to the olefin results in intermediate

C, which undergoes reductive elimination to form a C-H bond (Scheme 20). In order to examine the

mechanistic reason for the different reactivity of complexes 1 and 11, we have reacted complex 11

with D2. Upon reaction with excess D2 at room temperature immediate formation of the cis-dideuteride

complex 15 was observed (Scheme 21). No deuterium incorporation into the vinylic protons of COE

took place, implying that hydride migration to the COE ligand in the third step is most probably not

facile. As already mentioned before, the migration of a hydride is governed by sterics and by electron

density on the olefin. Either lower steric hindrance or higher electron density on the olefin inhibit the

migratory insertion, both of which are found in complex 11.

LnM+2H

H

LnM LnM+2H

H

R

LnM+2

H

RH2

R

R

AB

C

Scheme 20

N Ir

PiPr2

PiPr2

+PF6

11

D2 N Ir

PiPr2

PiPr2

+PF6

DD

+

HH

15 Scheme 21

3.2.1 Vinylic C-H Bond Activation of COE

A few years ago our group reported the vinylic C-H bond activation of COE upon addition of the PNP

ligand to [Ir(COE)2Cl]2 or to the cationic [Ir(COD)(CH3CN)2][BF4]. However, when

(tBuPNP)Ir(I)(COE)+ 1 was reacted with 10 equivalents of acetonitrile or with excess of LiCl at room

temperature, C-H bond activation of COE to form (tBu2PNP)Ir(III)(H)(COE)(X)+ (X= Cl or CH3CN),

complexes 16, 16' was observed60 (Scheme 22). The reaction can take place by two different

pathways; either by coordination promoted C-H bond activation61 or by trapping of an existing vinyl

hydride in solution (Scheme 22). Although there is no evidence for equilibrium between Ir(I)(COE)

and Ir(III)(H)(COE), we believe that coordination promoted C-H activation is less probable in this

system because such a process is quite rare when square planar d8 complexes are involved. Usually a 28

14e T-shaped intermediate is responsible for the activation (vide supra). Moreover, in the case where

C-H activation is promoted by a fifth ligand coordination, a much more labile system is used (not

involving a tridentate chelating ligand such as PNP). Interestingly, when complex 11 was reacted with

excess of acetonitrile in acetone, formation of a new complex was observed by NMR during a period

of one night at room temperature. This complex did not contain a hydride signal. Moreover, free COE

was detected, implying a ligand exchange process i.e. acetonitrile exchanged with COE, resulting in iPr(PNP)Ir(CH3CN)+ 17. As concluded before, COE is bound much stronger in complex 11 than in 1

because of steric reasons. Hence, we believe that complex 1 is in equilibrium with the vinyl hydride

complex 1', while complex 11 is not involved in such an equilibrium (or the Keq is very small) and

thus, acetonitrile simply replaced COE associatively resulting in 17 (Scheme 22).

N Ir

PiPr2

PiPr2

+PF6

11

Excess CH3CNN Ir

PiPr2

PiPr2

+PF6

NCCH325oC in Acetone N Ir

PiPr2

PiPr2

+PF6

NCCH3

N Ir

PtBu2

PtBu2

+PF6

1

N Ir

PtBu2

PtBu2

+PF6

16

X

H

17

5-10 eqs. CH3CN

N Ir

PtBu2

PtBu2

+PF6

H

25oC in Acetone

25oC in Acetone

or LiCl excess

X= ClX= CH3CN

1'

Scheme 22

In conclusion, we have shown here a rare example of two, iso-electronic, PNP based Ir(I), cationic

complexes that behave very differently as a result of of steric difference only. Both complexes are

electron-rich and are capable of H2 activation, however the less sterically hindered complex did not

react with C-H bonds. Moreover, only the more bulky one underwent hydrogenation of COE. Further

investigations are needed in order to verify and further clarify the reasons for these differences,

including DFT caculations

29

30

3.3 Double α-C-H Activation of Aliphatic and Aromatic Ethers

Synthesis and Reactivity.

3.3.1 Double α-C-H Activation of THF. Reversible α- Hydride Elimination.

Fischer-type carbenes are mostly known for the early transition metals, like tungsten or chromium,

synthesized by procedures involving several steps. In recent years examples of late-transition metals

(mainly iridium) Fischer type carbenes have been synthesized. The very simple synthesis involves C-H

activation of an ether followed by α-hydride elimination. Unlike reversible β-hydride elimination,

reversible α-hydride elimination is rare.40, ,41 42 In general, early transition metal (Ta, W) alkyls are

known to exhibit reversible, α–hydride elimination even in the presence of β hydrogens. Also in some

Ir complexes α-elimination was proposed to be faster than β-elimination. The heteroatom greatly

facilitates both C-H oxidative addition and α-elimination to give a carbene. Irreversible geminal α-

dehydrogenation of several cyclic ethers and amines by Os and Ru was observed. Carmona and co-

workers have prepared several Fischer type carbenes of Ir. They claimed that the O-coordination to an

unsaturated Ir(III) center facilitated metal attack to on the adjacent C-H bond, whereas the formation

of sufficiently strong C-H bonds with sacrificial alkyl or aryl leaving groups provided the

thermodynamic driving force needed for the formation of metal-carbene linkage. Very few examples

of reversible α-hydride elimination are known. Crabtree and co-workers showed a bis-chelating

amino-pyridine ligand where the α-hydride elimination is reversed upon addition of CO, acetone or

acetonitrile to the carbene solution. Only the cis-dihydrideo carbene showed reversed α-elimination. It

was claimed that the reacting Ir-H bond should be orthogonal to the carbene plane and aligned with the

empty p-orbital of the carbene carbon in order for the α-elimination to take place. Here we report the

reaction of (tBuPNP)Ir(COE)+ complex with THF resulting in double geminal C-H bond activation to

form a trans-dihydride carbene. A structure with hydride ligands trans to each other is thought to be

energetically unfavorable because of their strong trans effect. Moreover, addition of acetonitrile or CO

traps the hydrideo-furyl complex, implying the reversibility of the α-hydride elimination. The geminal

dehydrogenation of THF to form (tBuPNP)Ir(I)=COC3H6 and hydrogen is reported and seems to be

counter-anion dependent.

When complex 1a was heated in THF, selective double-α-C-H activation to form a Fischer-type

carbene complex 18 was observed (Scheme 23). (tBuPNP)Ir(alkyl)(H)+ was not observed at any

temperature, implying that the α-C-H migration process is very facile and that the carbene is much

more stable than the hydrideo-alkyl complex. Moreover, no β-H elimination to form vinyl-ether and

Ir(III)(H)(H) complex was seen. An X-ray analysis exhibits shortening of the Cipso-O bond (1.34Å),

characteristic of Fischer-type carbenes (Fig.9; Table 8). Moreover, closer examination of the structure

revealed that the THF ligand is coordinated almost perpendicularly to the PNP plane, and parallel to

the H-Ir-H line. Such geometry, imposed by the bulky tBu substituents, results in lack of alignment of

the Ir-H bond with the empty p-orbital of the carbene carbon. Realignment might be needed for the

reverse α-hydride migration process. One explanation for the stability of the carbene might be the high

barrier for rotation around the Ir=C bond. However, when one equivalent of CO gas was added to

complex 18, the quantitative formation of (tBuPNP)Ir(alkyl)(H)(CO)+ 19, (Scheme 23) was observed,

implying that the α-H elimination process is in fast equilibrium. Complex 19 is very stable and does

not eliminate CO. Upon addition of acetonitrile to a solution of 18 a similar complex 20 was obtained

(Scheme 23). However, in this case an excess of acetonitrile was needed (10 equivalents) to observe

by NMR the (tBuPNP)(alkyl)(H)(CH3CN)+ 20.

N Ir

PtBu2

PtBu2

+BarF-

THF60oC ;1hr N Ir

PtBu2

PtBu2

OH

H

10 eq. CH3CNN Ir

PtBu2

PtBu2

ONCCH3

HRoom Temperature

1a18 20

N Ir

PtBu2

PtBu2

OCO

H19

+BarF-

+BarF-+BarF-

1 eq, CO

Scheme 23

31

Figure 9 : POV-Ray drawing of 18 at 50% probability level.




Bond length [Å] 2.3076(19)

Selected bonds Ir(1)- P(3)

2.308(2) Ir(1)- P(2)

2.140(6) 1.923(7) 1.346(8) 1.484(9)

Ir(1)- N(6) Ir(1)- C(1) O(2)- C(1) C(3)- O(2)

Bond angles [deg] Selected bonds 81.87(16) N(6)- Ir(1)- P(2) 81.60(16) N(6)- Ir(1)- P(3) 179.5(2) C(1)- Ir(1)-N(6) 163.45(7) P(3)- Ir(1)-P(2)

The concentrations of complexes 18 and 20 vary with the temperature (Fig. 9a). At room temperature

the carbene concentration is higher while at -40 oC the alkyl hydride prevails. Together with SST

experiments, we conclude that complex 20 is in equilibrium with complex 18. The enthalpy (∆H) of

the process was calculate to be -6.7 ± 0.3 kcal⋅mol-1 implying an exothermic process. However, in the

absence of acetonitrile the equilibrium of α-hydride migration was not observed, implying that the

reverse process to form an alkyl hydride has positive enthalpy. Nevertheless, the coordination of

acetonitrile to the alkyl hydride to form complex 20 might be very exothermic, compensating for the

positive enthalpy of the hydride migration, resulting in negative enthalpy. The entropy (∆S) of the

process is 20 ± 1 cal⋅mol-1⋅K-1 resulting from decoordination of acetonitrile. In total, the Gibbs free

energy (∆G25 o

C) is equal to -12.75 ± 0.6 kcal⋅mol-1.

-40oC 10 eq. CH3CN-20oC 10 eq. CH3CN

-10oC 10 eq. CH3CN0oC 10 eq. CH3CN

25oC 10 eq. CH3CN25oC NO CH3CN

Complex 18 Complex 20

Figure 9a:31P {1H} NMR of complex 18 before and after addition of acetonitrile at various temperatures.

32

3.3.2 Dehydrogenation of The α-C Position of THF and TBME; Counter-Anion Effect.

Here we report the geminal dehydrogenation of THF without a sacrificial hydrogen acceptor, in

a heterolytic manner, mediated by the counter-anion. Examples for geminal dehydrogenation of THF

with concomitant H2 elimination are known with ruthenium and osmium, however, they involve M-H

complexes as the reactive speciess, resulting in carbene and dihydrogen complexes which then react

with a sacrificial olefin, resulting in further THF activation. To our knowledge, dehydrogenation of

THF in the α-C position with molecular hydrogen formation, using both hydrogen atoms at this

position, is not known. Moreover, elimination of hydrogen from a trans-dihydride metal complex, in a

heterolytic manner is rare. When complex 1b (OTf– = trifluoromethane sulfonate as a counter-anion)

was heated in THF, the major product was complex 18b. However, the hydrideo alkyl complex 21 and

a little of the Ir(I) carbene, complex 22 were also formed (Scheme 24). Due to the better coordination

of triflate anion (versus BArF-, BF4- or PF6

-) it was possible to observe complex 21. Interestingly,

prolonged heating resulted in H2 elimination and formation of complex 22. According to our group

experience, a plausible mechanism for hydrogen elimination can be deduced; as opposed to other

counter-anions, triflate can react with one of the trans-dihydride ligands as a base, to form triflic acid,

which in turn reacts rapidly with the other hydride to form dihydrogen (Scheme 24). Other counter-

anions (such as BArF-, BF4- or PF6

-) exhibit such reactivity only to a much lower extent. Addition of H2

to complex 22 resulted in regeneration of complex 18b. Interestingly, during heating complex 1b in tBuOMe at 60 oC for 12 hours, the trans-dihydride carbene 23 was observed together with the

hydrideo-alkyl intermediate 24 (Scheme 25). However, finally, formation of the Ir(I)=CHOtBu carbene

complex 25 was observed. 1H NMR revealed a carbenic proton at 15 ppm and in 13C NMR a signal

appeard at 260 ppm.

N Ir

PtBu2

PtBu2

+OTf-

THF60oC ;1hr N Ir

PtBu2

PtBu2

OH

H

N Ir

PtBu2

PtBu2

OOTf

H1b 18b 21

N Ir

PtBu2

PtBu2

O

22

+OTf-+OTf-

++

N Ir

PtBu2

PtBu2

OH

H

OTf

N Ir

PtBu2

PtBu2

O

H HTfO

H2

-COE

Scheme 24

33

N Ir

PtBu2

PtBu2

+OTf-

TBME60 oC; 12 hrs N Ir

PtBu2

PtBu2

HOH

H1b 23

+OTf-

+ N Ir

PtBu2

PtBu2

HO

H24

OTf+ N Ir

PtBu2

PtBu2

HO

25

+OTf-

observed af ter 1 hr observed after 1 hr less than 5% af ter one hour 85%af ter 12 hrs.

-COE

Scheme 25

3.3.3 Oxidation Dependent β-H Elimination?! Triple C-H Activation of THF by

(tBuPNP)Ir(I)(COE).

Thus far, the process of α-H elimination seemed to be much more facile and favorable than β-H

elimination. However, when the neutral complex 35 (see chapter 3.4) was heated in THF at 60 oC for

1.5 hrs, complex 26 was formed quantitatively. Complex 26 is a result of triple C-H activation of THF

(Scheme 26). The proposed mechanism involves oxidative addition of the C-H bond next to the

oxygen atom, followed by hydride migration to the benzylic position to yield the aromatic intermediate

26''. This Ir(I) species undergoes selective β-H migration as opposed to the cationic Ir(III) species 21

(see Scheme 5) which is formed from complex 1. The Ir(I) hydrideo alkene intermediate 27' activates

the vinylic C-H bond, resulting in complex 26. In support of this mechanism, upon reaction of

complex 18 with tBuOK at low temperature (-78 oC, NMR was performed at -50 oC), formation of

complex 26 was observed immediately. No de-aromatized intermediates were observed. Warming up

to room temperature resulted in no change in the spectrum (Scheme 27).

26, 26'' and 27' were not observed

THF60oC ;1.5hr N Ir

PtBu2

PtBu2

OH

H

26

N Ir

PtBu2

PtBu2

OH

26'N Ir

PtBu2

PtBu2

O

N Ir

PtBu2

PtBu2

O

H

27'

26''

THF C-Hactivation

C-Hactivation

H-migrationβ−H-elimination

N Ir

PtBu2

PtBu235

Scheme 26

34

N Ir

PtBu2

PtBu2

OH

H

18

+BarF-

1 eq. tBuOK

25oC or -50oCN Ir

PtBu2

PtBu2

OH

H

26 Scheme 27

While in the process of α-H elimination, a cationic Ir(III) is involved as intermediate, in the process

of β-H elimination a neutral Ir(I) intermediate is involved. Thus, the oxidation state of the

intermediates might have a crucial role in controlling the type of elimination process.

Penta-coordinated, d8 Ir(I) complexes are thought to be unstable relative to the corresponding square

planar complexes, unless there is low electron density on the metal center. Thus, an intermediate

where a hydride and a carbene are bound to an Ir(I) complex (formed after α-H elimination from

intermediate 26'') will not be stable. However, β-H elimination will result in the unstable intermediate

27' which will undergo C-H bond activation to form saturated Ir(III) complex 26. C-H bond activation

by an (NNN)Ir(I)-Me square planar complex was recently reported.62 DFT calculations suggested a

mechanism where the methyl group rotates outside the NNN ligand plain prior to the C-H bond

cleavage. When an Ir(I)-H square planar complex is involved (like in our case), such a rotation should

be facile.

3.3.4 Synthesis and Reactivity of Fischer-Type Carbenes of Aromatic Ethers Other Than

THF. Csp3-H vs Csp2-H Activation.

Studying the aliphatic C-H activation of ethers, we decided to compare it with the reactivity of

complex 1a with aromatic ethers (anisole derivatives). Interestingly, as was described earlier, when

complex 1a was heated in anisole, selective activation of the aromatic C-H bonds took place, with no

apparent aliphatic C-H activation. However, at higher temperatures an additional process took place in

parallel to the arene C-H activation, leading to formation of the trans dihydride carbene complex 28,

which eventually decomposed to (PNP)Ir(CO)+ 5 (Scheme 28).

35

N Ir

PtBu2

PtBu2H

+PF6-

C6H5OMe

>70oC ; few hrs

O

N Ir

PtBu2

PtBu2H

+PF6-

OCH2 N Ir

PtBu2

PtBu2H

+PF6-

OC

H H

30 28

N Ir

PtBu2

PtBu2

+PF6-

O

CH3

N Ir

PtBu2

PtBu2

+PF6-

5

COH2O

29

PhOH

10a

Scheme 28

This process was found to take place initially by C-H oxidative addition of the methoxy moiety

followed by α-H-elimination, resulting in carbene 28. DFT calculations revealed that the rate

determining step for this process is the formation of the σ-adduct from the O-coordinated anisole 29.

The arene C-H activation of anisole is kinetically preferred over the alkane C-H activation of the

methoxy moiety; moreover, the latter is converted eventually to complex 5. In addition to the

dihydrideo carbene complex 28, the alkyl hydride complex 30 was also observed by NMR in the

resction mixture, in equilibrium with 28. Although it was impossible to separate the two complexes, it

was possible to partially characterize them, and identify them as the carbene and alkyl hydride

complexes.

Interestingly, when complex 28 (see chapter 3.4) was heated further, it reacted with traces of

water to give the Ir(I)CO+ complex 5 (Scheme 28). Although Fischer carbenes are known to react with

nucleophiles, mostly early transition metals have shown such reactivity. Formation of phenol was

observed by GC-MS. Moreover, repeating the experiment with labeled anisole (13CH3-OPh), labeled

complex 5 was formed (Scheme 28). In order to eliminate the problem of aromatic C-H activation we

decided to use more bulky aryl ethers.

Upon reaction of the cationic Ir(I) complex 1 with 1,3,5-trimethoxybenzene, at 60 oC for 1hr, 31P

NMR revealed a signal at 56 ppm. A signal in 1H NMR, at -40 ppm was indicative for a hydride trans

to loosely occupied coordination site, implying aromatic C-H bond activation (Scheme 29).

36

N Ir

PtBu2

PtBu2H

+PF6-

OCH2

32

N Ir

PtBu2

PtBu2H

+PF6-

OC

H H

33

Complex 1 CH3OC9H11

60oC; 2 hrs

N Ir

PtBu2

PtBu2H

O

OO

+PF6-

1,3,5(CH 3O) 3C 6H 3

31

Scheme 29

Indeed, no carbene formation was observed, although the ratio between the aromatic C-H bonds to the

aliphatic ones was small (1:3). It can be explained by the higher "directing power" of two methoxy

groups, in directing the aromatic C-H to the metal, while there is only one oxygen atom per three

aliphatic C-H bonds in the case of anisole. Slow diffusion of pentane into a benzene solution of 31

resulted in orange crystals that were analyzed by X-ray. The structure of complex 31 was confirmed by

X-ray analysis, although the hydride was not detected. It is possible to see that one methoxy group is

closer to the metal resulting in a slight distortion. Moreover, a slight elongation of the Car-O bond is

observable (Table 9, Fig. 10). As 1,3,5-trimethoxybenzene is not hindered enough, we looked for

another substrate where aromatic C-H bond activation will be hindered. Upon reaction of complex 1

with 2,4,6-trimethyl-anisole, where no aromatic C-H bonds are easily accessible, two main signals

(70%) in a ratio of 44:56 corresponding to (tBuPNP)Ir(H)(H)(=CHOPh)+ complex 32 and

(tBuPNP)Ir(H)(CH2OPh)+ 33, respectively, were observed by 31P NMR. 1H NMR revealed a carbenic

proton at 14 ppm and a hydride signal at -8 ppm, characteristic of trans-dihydrides and a hydride at -28

ppm corresponding to the alkyl hydride complex 32. By SST it was possible to observe the equilibrium

between the alkyl hydride 33 and the carbene 32. A small amount of the carbonyl complex 5 was

observed as well (Scheme 29). Interestingly, when 1 was heated in 3,5-dimethylanisole at 70 oC an AX

pattern was observed in 31P NMR, implying a cyclometalation of the tert-butyl of the PNP ligand

resulting in almost pure complex 34 (Scheme 30). Complex 34 is most probably a result of C-O bond

cleavage, followed by cyclometalation (σ- bond metathesis or Ir(V) intermediate). However, the small

impurity was crystallized and the X-ray analysis revealed that even at the very sterically demanding

position, in between the methyl and the methoxy group, C-H activation is possible (Figure 11, Table

10) (Scheme 30).

37

N Ir

PtBu

PtBu2

+PF6-

OComplex 160oC; 12 hrs

N Ir

PtBu2

PtBu2H

O

+PF6-

3,5-(CH3)2C6H3OCH3 +

Minor34 34'

Scheme 30

Figure 10: POv-Ray drawing of 31 at 50% probability level.



38


Bond lengths (Å) Selected bond 2.066(6) Ir(1)- C(20) 2.142(5) Ir(1)- N(5)

2.328(2) 2.3311(18) 1.419(10) 1.404(8) 1.385(8) 1.399(9) 1.402(8) 1.433(9)

Ir(1)- P(4) Ir(1)- P(3) C(22)- O(22) C(21)- O(22) C(24)- O(25) C(25)- O(25) C(27)- O(28) C(28)- O(28)

Bond angles [deg] Selected bonds 166.30(6) P(3)- Ir(1)- P(4) 83.68(14) N(5)- Ir(1)- P(3) 83.12(14) P(4)- Ir(1)-N(5) 178.6(2) C(20)-Ir(1)-N(5) 95.58(18) C(20)- Ir(1)-P(4) 97.70(17) C(20)- Ir(1)-P(3)

Figure 11: POV-RAY drawing of 34' at 50% probability level.

hydrogen atoms and counter-anion are omitted for clarity.


39

Table 10: Selected bond lengths [Å] and bond angles [o] for 34'

Bond lengths (Å) Selected bond

2.3216(14) Ir(1)- P(3) 2.3208(15) Ir(1)- P(2)

2.134(4) 2.053(5) 2.425(4) 1.25(6) 1.441(7) 1.409(7)

Ir(1)- N(1) Ir(1)- C(1) Ir(1)- O(1) Ir(1)- H(1) C(9)- O(1) C(6)- O(1)

Bond angles [deg] Selected bonds 82.37(13) N(1)- Ir(1)- P(2) 80.41(13) N(1)- Ir(1)- P(3) 105 (2) C(1)- Ir(1)-H(1) 161.3(2) O(1)- Ir(1)-H(1) 104.2(2) P(3)- Ir(1)-P(2)

In conclusion, we presented here a rare example of revesible double geminal C-H bond activation of

ethers, resulting stereo-selectivly in trans-dihydride Fischer type carbenes of Ir. Moreover, a rare

example of H2 elimination to form Ir(I) carbenes (of THF and TBME) was shown to be dependent on

the counter-anion and more facile in the presence of triflate anion. Triflate might have reacted as a

base in deprotonating the trans-dihydride. We have exemplified the selective activation of aromatic C-

H bonds in the presence of (the weaker) methoxy C-H bonds. Only steric hindrance, hindering the

aromatic C-H bonds allowed the formation of carbenes under milder conditions. We have also shown

the reduced stability of oxy-aryl carbenes, that might result from less π stabilization by the oxygen

atom. This made possible the direct observation of the equilibrium between the carbene and its

hydrideo alkyl precursor. Interestingly, we have also demonstrated a rare nuchleophilc attack of water

on the carbene carbon of anisole resulting in Ir-CO complex and phenol. Last but not least, we have

shown a (seemingly) oxidation- dependent β vs α-H elimination in which the low-valent Ir complex

exhibited selective β-H elimination in contrast to the cationic Ir(III) complex with which no β H-

elimination was observed.

40

3.4 Metal - Ligand Cooperation in C-H and H2 Activation by An Electron-

Rich PNP Ir(I) System.

Facile Ligand Dearomatization – Aromatization as Key Steps.

Bond activation by metal complexes, in which both the metal center and the ligand play active,

synergistic roles can provide new opportunities in organometallic chemistry and catalysis.63 An

example is the Ru(II) catalyzed hydrogenation of unsaturated polar bonds, in which H2 activation

involves both the metal center and a polar (N or O based) ligand, followed by a concerted transfer of

acidic and hydrideic hydrogens to an unsaturated substrate. Here we report on a (PNP)Ir(I) (PNP= 2,6-

bis-(di-tert- butylphosphinomethyl)pyridine) system in which the PNP ligand and the metal act in

concert in H2 and C-H activation via dearomatization/aromatization processes of the ligand. Moreover,

our work raises the question whether a seemingly simple H2 oxidative addition to Ir(I) might actually

involve H2 activation by an Ir(III) intermediate.

Upon reaction of our previously reported electron rich cationic Ir(I) complex 164 with tBuOK in

THF at room temperature, a rapid color change from pink-red to violet-red was observed and

formation of novel neutral complex 35 was observed (Scheme 31).

N

PtBu2

PtBu2

Ir

35

N

PtBu2

PtBu2

Ir

1

+ PF6-

N

PtBu2

PtBu2

Ir

H ; 36 D ; 36a

D/H

H5/D5

N

PtBu2

PtBu2

Ir

H

Not detected in this process

37

THF; 25 oC

tBuOK

C6H6

C6H6 or C6D6

2 hrs; 60 oC

Scheme 31

41


Hydrogen atoms are omitted for clarity. For bond lengths and angles

see Table 11



2.334 Ir(1)- P(1) 2.363 Ir(1)- P(2)

2.089 2.134 2.119 1.423 1.351 1.506

Ir(1)- N Ir(1)- C(31) Ir(1)- C(24) C(24)- C(31) C(1)- C(2) C(7)- C(6)

Bond angles [deg] Selected bonds 160.12 C(24)- Ir(1)-N 157.12 C(31)- Ir(1)-N 161.82 P(3)- Ir(1)-P(2)

42

The 31P NMR spectrum of 35 exhibits an AB quartet centered at 33 ppm, indicating non-equivalent

phosphorous atoms. Signals at 5.4, 6.35, and 6.43 ppm in the 1H NMR spectrum, corresponding to

three protons, indicate de-aromatization of the pyridine ring. An X-ray crystallographic study of

complex 35 shows unambiguously that the pyridine ring underwent de-aromatization. Thus, the C(1)-

C(2) bond (1.35 Å) is much shorter than C(6)-C(7) (1.505 Å) (Table 11, Fig. 12). Such de-

aromatization following de-protonation of the benzylic protons is known65 and was shown by us to be

involved in Ru-catalyzed dehydrogenation of alcohols.65a

When a benzene solution of complex (PNP*)Ir(I) 35 (PNP*= de-aromatized PNP) was mildly heated

at 60 °C for 2 h, quantitative C-H activation to form the complex (PNP)Ir(I)(C6H6) 36, with no overall

change in oxidation state, took place (Scheme 31).

The 31P NMR spectrum of 36 exhibits a singlet at 55 ppm, indicating C2v symmetry. The benzylic

protons give rise to one signal at 2.8 ppm in the 1H NMR spectrum, implying re-aromatization of the

PNP ligand. The X-ray structure of 36 (Figure 13, Table 12) reveals that the iridium atom is located in

the center of a slightly distorted square planar geometry, with the phenyl group located trans to the

pyridine ring, perpendicular to the PNP plane.



see Table 12

43



2.2715(14) Ir(1)- P(1) 2.2674(14) Ir(1)- P(2)

2.087(4) 1.500(7) 1.485(7) 2.057(5)

Ir(1)- N(1) C(1)- C(2) C(6)- C(7) Ir(1)- C(24)

Bond angles [deg] Selected bonds 82.29(13) N(1)- Ir(1)- P(2) 82.82(13) N(1)- Ir(1)- P(3) 177.81 (17) C(24)- Ir(1)-N(1) 98.86(15) C(24)- Ir(1)-P(2) 164.71(5) P(3)- Ir(1)-P(2)

Upon reaction of complex 35 with C6D6, deuterium incorporation into a benzylic group of complex

36a was observed (Scheme 31), the 1H NMR spectrum revealing only three benzylic protons.66 While

no intermediates were directly observed in the C-H activation process, indirect evidence suggests that

intermediacy of the Ir(III) complex 37 is a viable possibility.

Thus, de-protonation of the cationic complex [(PNP)Ir(H)(C6H5)]PF6 2 in THF at -78 oC with tBuOK resulted in formation of the neutral Ir(III) complex 3767. Reaction follow up at -50 oC by NMR

showed that 37 was quantitatively converted to 36 after 10 h (Scheme 32). No intermediates were

observed. When the isotopomer complex 36a was reacted with tBuOK at -78 oC, an Ir-D signal was

observed at -47 ppm in the 2H NMR spectrum and no hydride was observed, indicating that no direct

Ir-D deprotonation took place. Moreover, upon warming 36a to room temperature, complex 36

incorporating a D-labeled benzyl "arm" was formed, as a result of migration of the deuteride ligand

from the metal to the "arm". These observations support the intermediacy of 37 in the C-H activation

of benzene.68

N

PtBu2

PtBu2

Ir

D/H

PF6-+

THF

-78 oCN

PtBu2

PtBu2

Ir

D/HObserved at -78 oC

10 hr, -50 oC

N

PtBu2

PtBu2

Ir

D/H

H5/D5

H ; 2 D ; 2a

H ; 37 D ; 37a

CO, 1 eq.N

PtBu2

PtBu2

Ir

H ;38D ;38a

CO

C6D6

1. CO 1 eq.

2. tBuOK CO 1 eq.

tBuOK

D/H

H5/D5

H5/D5

H5/D5D/HH ;36D ;36a

Scheme 32 44

36 Surprisingly, when the Ir(I) complex was reacted with one equivalent of CO in benzene at 25 oC, oxidation of the metal center took place, quantitatively forming the Ir(III) phenyl hydride complex

38 38. Complex was synthesized independently by deprotonation of [(PNP)Ir(C6H6)(H)(CO)]PF6 42

(Scheme 32). This process might take place by reversible proton migration from the benzylic position

to the metal center, followed by trapping of the neutral phenyl hydride complex by CO.69 Complex 37

38 was thermally stable (up to 80 oC) in solution and did not eliminate benzene, similar to its cationic

aromatic analogue.2

36Remarkably, upon reaction of complex with 1eq of H2 at 25 oC in benzene (Scheme 33), only the

trans dihydride complex (PNP)Ir(H)2(C6H5) 39 was observed. The two equivalent hydride ligands give

rise to a triplet at -8.3 ppm in the 1H NMR spectrum, indicative of a trans-dihydride arrangement.

There is no evidence for the formation of the cis- dihydride complex.70 While cis- to trans-

isomerizations of octahedral Ir dihydrides are known,71 the barrier is high71b and the process requires

heating.71a Thus, 39 is likely to be the kinetic product. X-ray structure analysis of 39 (Fig. 14; Table

13) shows a slightly distorted octahedral geometry with the trans-dihydride ligands perpendicular to

the PNP plane.

1 eq. H2(D2)

N

PtBu2

PtBu2

Ir

H Not detectedin this process N

PtBu2

PtBu2

Ir

H ; 39

37D/H

N

PtBu2

PtBu2

Ir

36H

D/HD ; 39a

N

PtBu2

PtBu2

Ir

H

H H

THF

Scheme 33

45



see Table 13



2.113(4) 1.70(6) 1.62(6) 2.067(5)

Ir(1)- N(1) Ir(1)- H(2) Ir(1)- H(1) Ir(1)- C(24)

Bond angles [deg] Selected bonds 82.29(13) N(1)- Ir(1)- P(2) 82.82(13) N(1)- Ir(1)- P(3) 178.19 (17) C(24)- Ir(1)-N(1) 98.84(14) C(24)- Ir(1)-P(1) 164.79(5) P(3)- Ir(1)-P(2)

Significantly, reaction of the Ir(I) complex 36 with D2 under the same conditions did not yield the Ir

di-deuteride. Rather, the Ir(H)(D) complex 39a was obtained, with incorporation of one deuterium

atom into the benzylic "arm". This indicates the involvement of the benzylic carbons in the activation

of H2. It might be suggested that complex 37 is formed in solution in low concentration and is

responsible for the unusual reactivity with H2. Indeed, complex 37 reacts with H2 even at low

temperature (-78 oC) to give complex 39. Coordination of H2 to complex 37 followed by its

deprotonation by the amide nitrogen72 or directly by the ligand “arm” may lead to formation of

complex 39 (Scheme 33). Intriguingly, regardless of the exact mechanism, our evidence raises the

possibility of activation of H2 by an Ir(III) imtermediate, in an overall oxidative addition of H2 to Ir(I).

46

In conclusion, a number of unusual reactions are reported, in which the PNP ligand takes an active

role in the activation of H2 and benzene, via facile aromatization/dearomatization processes of the

ligand. The new, de-aromatized electron-rich PNP based Ir(I) complex 35 activates benzene to form an

Ir(I)-Ph complex, which upon treatment with CO undergoes a surprising oxidation process to form the

Ir(III) complex 38, involving proton migration from the ligand "arm" to the metal, with concomitant

dearomatization. Another interesting transformation of 36 is the stereoselective activation of molecular

hydrogen to exclusively form the trans-dihydride 39. Our evidence, including D-labelling, suggests

that the 16e Ir(I) complex 36 37 may be oxidized to the (independently prepared) 16e Ir(III) which

could be the actual complex undergoing H2 activation. Further theoretical investigations on this system

yielded some insight on the process of hydride migration to the PNP benzylic position to form

complex 35 37 from complex . It was postulated from calculation that water might bridge between the

migrating hydride to the anionic benzylic carbon via the oxygen, thus reducing the barrier for

migration (Scheme 34). Computationally, no other energetically favorable explanation was found for

this process.

N

PtBu2

PtBu2

Ir

H

N

PtBu2

PtBu2

Ir

OH

H

HO

H

H

Scheme 24

47

3.5 Activation of H2 and Vinylic C-H by The Neutral (tBuPNP*)Ir(I)(COE)

(iPrPNP*)Ir(I)(COE)

Metal hydride complexes are important intermediates in many catalytic processes, such as C-H, H-H

and other H-X (X= O, N, S, etc) bond cleavage reactions. The reactivity of molecular hydrogen with

transition metal complexes is a very important process in the industry. Metal hydrides are involved in

dehydrogenation processes of alcohols, hydrocarbons, amines, dehydrogenative coupling etc.

We have reported the reactivity of the cationic (PNP)Ir(I) complexes 1 and 11 towards H2 (vide

supra). Moreover, we have raised the possibility that complex 1 is in equilibrium with the vinyl

hydride complex 1', while complex 11 is not involved in such an equilibrium (or the Keq is very

small). In this chapter a comparison between the two neutral complexes (tBu, iPr) is made. For that

purpose we have synthesized the neutral iPrPNP*Ir(I)(COE) complex 40 by deprotonation of its

cationic precursor. The reactivity of the neutral complexes with hydrogen was studied and some

interesting results were observed. When complex 35 was reacted with one equivalent of H2 in pentane,

complexes (tBuPNP)Ir(H)3 41 (minor) and (tBuPNP)Ir(H)2(COE) 42 (major) were observed. Complex

42 was completely converted to complex 41 when excess H2 was used (Scheme 35).

H2

PentaneN Ir

PtBu2

PtBu2

H

H

42

N Ir

PtBu2

PtBu2

41

HH

H

N Ir

PtBu2

PtBu235

N Ir

PiPr2

PiPr240

N Ir

PiPr2

PiPr243

H

H

HH2

Pentane

Scheme 35

However, when complex 40 was reacted with H2 only iPr(PNP)Ir(H)(H)(H) 43 was formed (Scheme

35). The oxidative addition of H2 to an Ir(I) 16e square planar complex was described earlier in

chapter 3.2 where both the cationic complexes underwent H2 addition. H2 activation with the neutral

complexes should not be, in principle, different. However, a simple H2 activation mechanism would

not explain the formation of the unexpected complex 42. Complexes 41 and 43 were formed, most

probably, as a result of activation of two H2 molecules.73 In order to answer the question of complex

42 formation we conducted several experiments. Two routes for H2 activation other then oxidative

addition are possible (Scheme 36).

48

42

N Ir

PtBu2

PtBu2

HH

N Ir

PtBu2

PtBu2

N Ir

PtBu2

PtBu2H42'''35

Second mechanism

First mechanism N Ir

PtBu2

PtBu235

H2

N Ir

PtBu2

PtBu2

H

N Ir

PtBu2

PtBu2H

HH

N Ir

PtBu2

PtBu2

H

H

42'

Not observed

Not observed Scheme 36

The first route involves heterolytic H2 activation along the Ir-Cbenzylic line to form intermediate

Ir(I)(H)(COE) 42', followed by C-H activation to form 42. The second route involves reversible C-H

activation 42''' 35 followed by heterolytic cleavage of H2 along the Ir-Cbenzylic axis, resulting in

42 (Scheme 36). Both mechanisms might be feasible, although the following experiments seem to

support the second one. When the cationic complex 1 was reacted with a hydride source, formation of

complex 42 was observed in 90% yield by NMR. It could have resulted from trapping of the hydrideo

vinyl complex (see chapter 3.2.) by the hydride (like Cl- and CH3CN) (Scheme 37, I). Another option

is the C-H bond promotion by hydride coordination (Scheme 37, III), however, NO cis- isomer was

observed and no apparent preference to the trans- isomer was seen, with this kind of intermediate.

However, the first proposed mechanism offers a better explanation to the formation of the trans-

isomer (Scheme 37, I). Moreover, when a D-35 complex (where the benzylic positions are deuterated)

was left in pentane at 25 oC for a few days, deuterium incorporation into the vinylic positions of COE

was observed. Incorporation of protons from the benzylic position can occur, to our understanding, via

a mechanism involving reversible C-H vinylic bond activation followed by reversible aromatization of

the PNP ligand (Scheme 38). The process of aromatization/dearomatization was described in chapter

3.4 with the (PNP)IrPh complex 36 in the reaction with H2. Bearing in mind all the experimental

evidence, we can estimate that H-H bond activation by the neutral (PNP)Ir(I)(COE) complex can occur

49

in two parallel processes; (1) oxidative addition of H2, (2) heterolytic cleavage of H-H bond by an

Ir(III)(H)(COE), i.e. oxidation of the metal followed by H-H cleavage.

N Ir

PtBu2

PtBu2

+PF6-

N Ir

PtBu2

PtBu2

+PF6-

1H

NaEt3B

50

H 1 eq.-30 oC- R.T.

N Ir

PtBu2

PtBu2

H

H42

I

II N Ir

PtBu2

PtBu2

+PF6-

1

N Ir

PtBu2

PtBu235

NaEt3B

-30 oC- R.T.

H 1 eq.

H-H

2 possible pathwaysSee Scheme 36

H H-H

III N Ir

PtBu2

PtBu2

+PF6-

1

N Ir

PtBu2

PtBu2

NaEt3B q.

-30 oC- R.T.

H

H 1 e H

Proposed Mechanisms Scheme 37

N Ir

PtBu2

PtBu2

D-35

D

DD

N Ir

PtBu2

PtBu2

D

H

D

DH

pentane

N Ir

PtBu2

PtBu2

D

DD

N Ir

PtBu2

PtBu2

D

DD

H

H

N Ir

PtBu2

PtBu2

D

D

H

D

25 oC; 12 hrs

Scheme 38

51

3.6 Oxygen Insertion Into M-H Bonds (M= Ir, Rh)

In chapter 3.4 I have described the synthesis of neutral iridium (PNP)Ir(C6H6) 36. Interestingly,

when complex 36 was reacted with 0.5 equivalent of O2, immediate formation of the neutral Ir(III)

hydroxo phenyl complex 44 was observed. No intermediates, such as hydroperoxo species were

observed during the reaction. When the reaction was repeated with 30 equivalents of the radical

scavenger BHT and under dark conditions, no retardation of the reaction was seen. Thus, it is likely

that the reaction mechanism is not a radical one. From the stochiometric ratio between oxygen and

complex 36 we can estimate that both atoms of O2 were incorporated, and that this reaction is

bimolecular. When complex 36 reacted with oxygen at -50 oC, formation of an unknown complex was

observed together with the starting complex 36. The NMR ratio between the two complexes was 1:1,

implying that the 0.5 eq. of oxygen reacted with only 0.5 eq. of complex 36. This species has

disappeared while warming to room temperature, resulting in complex 36. However, immediate

reaction with oxygen was seen even at 0 oC to form complex 44. Few suggested mechanisms are

presented on Scheme 39. While distinguishing between the mechanisms is difficult, the overall

reaction can be regarded as oxygen insertion into the Ir-H bond of intermediate 37. Interestingly, when

complex 44 was reacted with CO2 formation of a new complex was observed by NMR (Scheme 40).

The 31P NMR spectrum revealed a singlet at 28 ppm implying re-aromatization of the PNP pyridine

ring. Yellowish prismatic crystals were obtained from slow diffusion of pentane into a benzene

solution of 45. X-ray crystallographic study revealed a carbonate ligand coordinated in an η2 fashion

and a phenyl coordinated in the axial position trans to a carbonate oxygen (Fig. 15; Table 14).

Neutral PNP based rhodium complexes have also been synthesized. One example of such a complex

is (tBuPNP)Rh(H) 46 (Chepter 3.8). This complex reacted with O2 (0.5 eq. or excess) immediately to

form the neutral hydroxo complex 47. This reaction is a direct insertion of O2 into a metal hydride

bond. However, no hydro-peroxo speciess were observed (Scheme 41).

0.5 eq. O2

N

PtBu2

PtBu2

Ir

H Not detectedin this process

N

PtBu2

PtBu2

Ir

36

N

PtBu2

PtBu2

Ir

HO 44

N

PtBu2

PtBu2

Ir

HOO

O2

Not detectedin this process

I

N

PtBu2

PtBu2

Ir

-OO

52

N

PtBu2

PtBu2

Ir

H

III

N

PtBu2

PtBu2

Ir

O

N

PtBu2

PtBu2

Ir

-OH

III



37

44'

37'

44''

44a'

O


O2

Scheme 39

N

PtBu2

PtBu2

Ir

HO 44

CO2N

PtBu2

PtBu2

Ir

45

OO C

O

OC O

N

PtBu2

PtBu2

Ir

O

H

H

O

C O

N

PtBu2

PtBu2

Ir

O

H

Proposed Mechanism

Scheme 40

N

PtBu2

PtBu2

Rh

46

H N

PtBu2

PtBu2

Rh

47

OHO2

0.5 eq. or excess

Scheme 41

53



see Table 14


Bond lengths (Å) Selected bond 2.376(4) Ir(1)- P(3) 2.362(4) Ir(1)- P(2) 2.088(4) 2.062(5) 2.221(7) 2.043(5) 1.306 1.320 1.246

Ir(1)- N(11) Ir(1)- O(1) Ir(1)- O(2) Ir(1)- C(1) O(1)- C(7) O(2)- C(7) O(3)- C(7)

Bond angles [deg] Selected bonds 116.64 N(1)- Ir(1)- O(1) 177.67 (17) O(2)- Ir(1)-N(11) 87.04 C(1)- Ir(1)-N(11) 162.45 P(3)- Ir(1)-P(2)

3.7 C-X Bond Activation (X= Br, Cl or O) by PNP Based Iridium and Rhodium

Complexes.

When complex 1 was reacted with bromobenzene, no C-Br activation products were observed (vide-

supra). However, when 1 was heated in 3,5- dimethyl-bromobenzene at 60 oC for 12 hours, C-Br

activation took place quantitatively, without any observable C-H activation products, as a result of the

aromatic C-H bonds being sterically hindered (Scheme 42). Interestingly, the reaction resulted in the

cyclometelated Ir(III) complex 48. Complex 48 can result from C-Br bond cleavage followed by σ-

bond metathesis or C-H bond activation to form an Ir(V) intermediate and C-H reductive elimination

of m-xylene (Scheme 42). An X-ray crystallographic study of complex 48 revealed a strained 4-

membered ring formed as a result of cyclometalation (the C-H cleavage of one tBu group on the

phosphine), resulting in a distorted square-pyramidal geometry (Fig.16; Table 15). The reaction of the

Ir-Ph complex in section 3.2 supports the assumption that the mechanism involves C-Br activation as

the first step prior to the cyclometalation (and not vice versa). A very similar cyclometelated complex

has resulted from C-O bond cleavage of 3,5-dimethylanisole, complex 34. This process is also

preceded by CH3-O bond cleavage, and followed by methane liberation (Scheme 43).

N Ir

PtBu

PtBu2

+PF6-

60oC; 12 hrs

3,5(CH3)2C6H3Br

48

Br +

N Ir

PtBu2

PtBu2

+PF6-

Br N Ir

tBuP

PtBu2

CH2H

Br-

+PF6-

N

PtBu2

PtBu2

Ir

1

+ PF6-

Scheme 42

Rh cationic complexes have also been synthesized. Thus far, no stable Rh alkyl hydride complexes

were isolated. However, (PNP)Rh(I)-L (L= N2, THF etc) complexes were reactive toward C-Br bonds

(both benzylic and phenylic). When tBu(PNP)Rh(I)(N2)+ 49 was heated in bromobenzene at 120 oC for

one night, the phenyl bromide complex 50 was obtained in nearly quantitative yield (Scheme 44). C-Br

bond cleavage was also observed when complex 51 reacted with 10 equivalents of benzyl bromide in

THF at room temperature for one night.

54


Hydrogen atoms and counter anion are omitted for clarity.




2.337 (4) Ir(1)- P(1) 2.278(4) Ir(1)- P(2)

2.098(4) 2.456(5) 2.081(7) 1.873(5) 1.867 1.562 1.564

Ir(1)- N(1) Ir(1)- Br(1) Ir(1)- C(29) C(13)- P(1) C(23)- P(2) C(23)- C(29) C(13)- C(19)

Bond angles [deg] Selected bonds 178.15 N(1)- Ir(1)- Br(1) 97.25 (17) P(1)- Ir(1)- Br(1) 83.10 C(29)- Ir(1)-N(1) 167.76 P(1)- Ir(1)-P(2)

55

No α- hydrogen elimination to form a Schrock carbene was observed. Similar to complex 50, the

crystal structure of 52 revealed the benzylic group to be trans to a vacant coordination site (Fig. 17;

Table 16). In both cases no cyclometalation was observed. It can be explained in two ways.; (1) The

metal center (Rh) is more bulky (than Ir) thus, formation of a 4-membered ring will cause an even

greater strain. Moreover, the σ-C-H bond adduct formed prior to activation will also be more strained

in the Rh case. (2) If the mechanism involves an M(V) complex then, it will be less probable that

rhodium will be at such high oxidation state than iridium, accounting for this difference in reactivity.

Among the C-X (X = Cl, Br, I) bonds the activation of the relatively inert C-Cl bond is the most

challenging.74 The oxidative addition of C-Cl bonds, especially of dichloromethane, requires an

electron-rich rhodium center. Only few examples of simple oxidative addition of dichloromethane

were reported.75 Indeed, when complex 49 was dissolved in dichloromethane and was left at room

temperature for one night the C-Cl oxidative addition product complex 53 was observed as the sole

product (Scheme 45).

N Ir

PtBu

PtBu2

+PF6-

O60 oC; 2 hrsN Ir

PtBu2

PtBu2H

O

+PF6-

+

Minor34 34'

N Ir

PtBu2

PtBu2

+PF6-

O

H3C

N Ir

BuPt

PtBu2

+PF6-

-o

CH2

H3C H

N Irv

PtBu

PtBu2

+PF6-

-O

H

H3C

Or

CH4CH4

N Ir

PtBu2

PtBu2

+PF6-

1

3,5 dimethylanisol

Scheme 43

56

N

PtBu2

PtBu2

Rh

49

L

50

120oC; 12hrs

+BF4-

BromobenzeneN

PtBu2

PtBu2

Rh

+BF4-

Br

52

N

PtBu2

PtBu2

Rh

+BF4-

Brbenzyl bromide

25 oC; 12 hrsN

PtBu2

PtBu2

Rh

51

L

+BF4-

Scheme 44

N

PtBu2

PtBu2

Rh

49

L

53

25 oC; 12 hrs

+BF4-

N

PtBu2

PtBu2

Rh

+BF4-

Cl

ClH2C

CH2Cl2

Scheme 45

57


Hydrogen atoms and counter anion are omitted for clarity.




2.075(4) Rh(1)- N(1) 2.096(5) Rh(1)- C(20)

2.2980(14) 2.3622(13) 2.4446(10)

Rh(1)- P(2) Rh(1)- P(1) Rh(1)- Br(1)

Bond angles [deg] Selected bonds 90.23(17) N(1)-Rh(1)-C(20) 86.01(14) C(20)-Rh(1)-P(2) 104.93(14) C(20)-Rh(1)-P(1)

164.44(5) P(1)-Rh(1)-P(2) 173.31(1 Br(1)-Rh(1)-N(1)

58

59

3.8 PNP Based Rhodium Complexes. Synthesis and Reactivity.

In the former chapters (3.7 and 3.6) we have shown some examples for the reactivity of PNP based

rhodium complexes (neutral and cationic). Here we will describe in some details the synthesis of the

PNP based rhodium precursors and their reactivity towards H-H, C-H and O-H bonds. Upon reaction

of the tBuPNP ligand with the cationic rhodium precursor, Rh(Aceton)2(COE)2+PF6

-, the Rh(I)-L (L =

N2, acetone, THF) complex 49 was formed, as opposed to the iridium case (Scheme 46). In the case of

iridium, the cyclooctene Ir(I) complex 1 was formed, implying that the steric hindrance around the

rhodium is higher, correlated with its smaller ionic radius. However, when iPrPNP was used, the

cyclooctene Rh(I) complex 51 was formed (Scheme 46). Both complexes 49 and 51 exhibit ligand

exchange chemistry with no stable C-H products observed. However, as described earlier, C-X (X=

Br, Cl) bond activation is facile with both complexes. Rhodium complexes are known to be less

reactive in oxidative addition reactions, especially of C-H bonds. The stability of M-C or M-H bonds

increases upon going down a triad, i.e. going from Co to Ir, and so does the thermodynamic tendency

to undergo oxidative addition. Rhodium is found in the middle and this is reflected more or less in its

chemistry. Indeed, from the CO stretching of complex 54 (1986 cm-1) we can deduce that the electron

density on the metal center is much lower than that on Ir-CO complex 5 (1964 cm-1). However, these

complexes react with hydrogen to form the cis-dihydride complexes 55 and 56. These complexes are

also less stable than in the case of iridium, and exhibit hydrogen elimination (Scheme 47). In some

cases there is a need for a driving force in order to facilitate C-H bond activation. Examples of such a

force include release of strain after activation, elimination of a stable product (such as methane or

benzene) resulting in a new alkyl-M bond, and aromatization like in the example presented in earlier

section(Chapter 3.4), when the neutral IrCOE complex 35 reacted with benzene to form the Ir-Ph

complex 36 while re-aromatizing the pyridine ring. Indeed, when the neutral Rh(I) complexes 57 and

58 reacted with benzene, Rh(I) phenyl complexes were formed (Scheme 48). Only complex 58 showed

relatively clean formation of (iPrPNP)Rh(C6H5) 59 (Scheme 48). This complex was probably formed

after C-H oxidative addition followed by hydride migration to the benzylic arm, resulting in

aromatization of the pyridine ring. As opposed to the cationic Rh(I) complexes, the formation of stable

aryl-Rh complex was possible due to the fact the driving force provided by aromatization. Similarly,

when the neutral complexes reacted with H2, formation of (tBuPNP)Rh(H) 46 was observed.

Interestingly, complex 46 reacted with water under mild conditions to yield the dihydrideo hydroxo

complex 61 which in turn liberates hydrogen to form complex 47 (Scheme 49). Complex 46 can also

activate hydrogen to form complex 62 (tBuPNP)Rh(H)3. When complex 46 was reacted with CO gas

the formation of the neutral CO complex 54' (tBuPNP*)Rh(CO) and hydrogen was observed, implying

(as in the case of Ir-Ph) an equilibrium between aromatized PNP and de-aromatized one (Scheme 49).

N

PR2

PR2

Rh LN

PR2

PR2

Rh(Aceton)2(COE)2+BF4

-+

R= tBu L=N2(49), Aceton, THF

R= iPr L=COE 51

+BF4-

Scheme 46

N

PR2

PR2

Rh LH2

R= tBu L=N2(49), Aceton, THF

R= iPr L=COE 51

+BF4-

N

PR2

PR2

Rh

R= tBu 55

R= iPr 56

+BF4-

H

HVacuum or Heat

N

PR2

PR2

Rh CO

+BF4-

R= tBu 54; υco= 1986 cm-1

Ir-CO 5; υco= 1964 cm-1) Scheme 47

80oC; 12hrs

R= iPr L=COE 51

tBuO-K+

R= tBu L=N2 49

N

PR2

PR2

Rh LN

PR2

PR2

Rh L

+BF4-

R= iPr L=COE 58

R= tBu L=N2 57

C6H6N

PR2

PR2

Rh

R= iPr 59R= tBu 60

Scheme 48

60

H2N

PR2

PR2

Rh L

R= tBu L=N2 57

N

PR2

PR2

Rh HH2

N

PR2

PR2

RhH

H62

H

H2O

CO N

PR2

PR2

RhH

HO61

H

N

PR2

PR2

Rh CO

N

PR2

PR2

Rh

+BF4-

H

H

R= tBu 55

tBuO-K+

54'

H2R= iPr L=COE 58

R= iPr 56

R= tBu 46

N

PR2

PR2

Rh OH

R= tBu 47

-H2

Scheme 49

61

3.9 Nucleophilicity of (PNP)IrIPh. Reactivity With MeI, I2 and CO2.

(PNP)IrIPh 36 is an electron rich 16e Ir square-planar complex. Such speciess are known to activate

electrophiles (RX, HX or X2) heterolytically, to form the trans isomers, in a nucleophilic oxidative

addition. Ligand dissociation to form 14e species is not needed, unlike the case of C-H oxidative

addition processes. Indeed, when 36 was reacted with excess of MeI in THF at room temperature,

immediate color change from grey-violet to red-purple was observed (Scheme 50). The 31P NMR

spectrum revealed two broad signals at 22 ppm and 34 ppm. 1H NMR signals were very broad. Upon

cooling the solution to -30 oC the signals sharpened, allowing detection of two proton systems in 1H

NMR. A characteristic signal at 1.7 ppm (3 protons by integration) is compatible with a M-CH3 moeity

which is coordinated trans- to a vacant coordination site. Another M-CH3 group gave rise to a signal at

2.5 ppm and is most probably coordinated trans to the pyridine ring. A possible explanation for the

broadening of the spectrum is pseudo rotation in which the methyl and phenyl groups exchange

positions from apical to axial and vice versa (Scheme 50). Such isomerization might have a low barrier

and is driven by the strong trans effect of both ligands, "competing" on the vacant site. Complex 63 is

very stable at higher temperatures (80 oC) and did not eliminate toluene. Slow evaporation of the THF

solution of 63 resulted in crystals suitable for X-ray analysis (Fig.18; Table 17). X-ray revealed only

the isomer where the methyl is trans to the pyridine ring. The Ir-N bond (2.150 Å) is significantly

longer than other Ir-N bonds in similar systems where a ligand with lower trans effect (like oxygen) is

trans to the pyridine (see Fig. 15, 14 etc.). When one equivalent of CO was added to a solution of 63 in

THF, one major complex 64 was formed (Scheme 50).

CH3I

36

N Ir

PtBu2

PtBu2

N Ir

PtBu2

PtBu2

63

CH3 N Ir

PtBu2

PtBu2H3C63'

++I I

N Ir

PtBu2

PtBu2H3C64

+ I

COCO ; 25 oC

Scheme 50

62

This complex was characterized by X-ray as the isomer bearing the methyl at the axial position trans

to the CO and the phenyl is trans to the pyridine ring (Fig. 19; Table 18). The M-CH3 bond in 64

(1.975 Å) is shorter significantly from the M-CH3 bond in 63 (2.099 Å). Upon reaction of complex 63

with tBuOK in THF, complex 65 was formed in quantitative yield (Scheme 51). Further heating of

complex 65 for 12 hrs at 70 oC resulted in no reaction and methyl migration to the benzylic "arm"did

not take place, unlike the observation in the case of the hydrideo phenyl neutral complex 37. When the

Ir-Ph complex was reacted with I2 at room temperature, immediate color change was observed to

brownish. The 31P NMR spectrum revealed an AX quartet signal with P-P coupling of 360 Hz centered

at 15 ppm, corresponding to one major complex (75%). This complex was also a product of reaction

between the cationic IrI(COE) complex and 3,5-dimethyl-bromobenzene (reported in earlier chapter

3.7) which was found to be the cyclometelated IrIII-Br complex. We believe that after activation of I2

to form Ir(Ph)(I)(I), elimination of benzene, through sigma-bond metathesis with C-H bonds of the tBu

substituents, is a possible mechanism (Scheme 52).

N Ir

PtBu2

PtBu2

63

CH3 N Ir

PtBu2

PtBu2H3C63'

+ +I I

tBuOK; 1eq.

THF; 25 oCN Ir

PtBu2

PtBu2

65

CH3 N Ir

PtBu2

PtBu2H3C65'

Scheme 51

N Ir

PtBu

PtBu2

+I-

Room Temp.

I2

46

I +

N Ir

PtBu2

PtBu2

+I-

45

I

N Ir

BuPt

PtBu2

CH2H

I-

+I-

36

N Ir

PtBu2

PtBu2

Scheme 52

63

64




Table 17: Selected bond lengths [Å] and bond angles [o] for 63 Bond lengths (Å) Selected bond

2.3213(10) Ir(1)- P(3) 2.3671(9) Ir(1)- P(2)

Ir(1)- N(11) 2.150(3) Ir(1)- C(1) 2.037(3)

Ir(1)- C(7) 2.099(3) Bond angles [deg] Selected bonds

91.70(11) N(11)-Ir(1)- C(1) 171.95(10) C(7)- Ir(1)-N(11)

96.22(13) C(1)- Ir(1)-C(7) 162.42(3) P(3)- Ir(1)-P(2)

64 at 50% probability level. Figure 19: POV-RAY drawing of



65

Figure 19: ORTEP drawing of 64 at 50% probability level.



Table 18: Selected bond lengths [Å] and bond angles [o] for 64 Selected bond Bond lengths (Å) Ir(1)- P(3) 2.4147(11) Ir(1)- P(2) 2.4141(12) Ir(1)- N(11) 2.149(3) Ir(1)- C(1) 2.134(10) Ir(1)- C( 1.954(8) 2)

2.088(4) Ir(1)- C(4) 1.098(10) C(1)- O(2)

Selected bonds Bond angles [deg] N(11)-Ir(1)- C(1) 90.10(11) C(2)- Ir(1)-N(11) 95.70(3) C(1)- Ir(1)-C(2) 173.8(11) C(4)- Ir(1)-N(11) 176.80(15) C(2)- Ir(1)- C(4) 87.3(3) C(1)- Ir(1)- C(4) 86.8(11) P(3)- Ir(1)-P(2) 159.13(4)

An interesting reaction was observed between the IrIPh and CO2. When 5 equivalents of CO2 were

introduced into a benzene solution of 36 at room temperature, a mixture of complexes was observed by

NMR. However, when CO2 was introduced at 80 oC complex 66 was formed and an A/B quartet was

observed by 31P NMR, implying non-equivalent phosphines. However, 1H NMR revealed an

aromatized pyridine ring, suggesting substitution of a benzylic proton by another group. Indeed, the 1H

NMR spectrum exhibited a hydride signal at -24 ppm, corresponding to one hydride trans to an

occupied coordination site and a signal at 5.1 ppm which is characteristic to a proton next to

carboxylate. This carboxylate is coordinated to the metal center trans to the hydride. Such reactivity

supports our assumption that an equilibrium between the IrIPh and the IrIII(H)(Ph) indeed exists, as

exemplified in chapter 3.4 involving reaction of an IrIPh complex with CO and H2 (Scheme 53).

36

N Ir

PtBu2

PtBu2

N Ir

PtBu2

PtBu2H

CO2

N Ir

PtBu2

PtBu2

H

OC

O

N Ir

PtBu2

PtBu2

H

O

OH

66

80 oC

CO2

Scheme 53

66

3.9.1 Activation of Diphenylsilane and CO2 by The (tBuPNP*)Ir(I)(COE) Neutral

Complex: Ligand Assisted Activation.

In earlier chapters (3.4, 3.6 and 3.9) we have demonstrated unique reactivity in which the PNP ligand

take an active role in bonds activation of several types, C-H, H-H and O=O. In this chapter we report

the reaction of complex 35 with CO2 and diphenylsilane. Silcon is often polarized in the opposite sense

to carbon. With some exceptions, silicon is depleted of negative charge Siδ+–Xδ-.76 This difference is

exemplified by the reaction of Si-H bonds with nucleophiles such as Me- (Scheme 51; in the absence

of phenyl groups on silicon other reaction pathways are followed). The activation of Si-H bond by an

iridium complex is usually very facile due to low BDE (75-90 kcal/mole) and the formation of two

bonds; M-H and M-Si bonds. We were then interested in the activation of diphenylsilane by the neutral

(tBuPNP*)Ir(I)(COE) complex 35. Will the arm be involved in the activation process and how?

Interestingly, when complex 35 was reacted with diphenylsilane, two main complexes were formed. 31P NMR indicated that a non-symmetric system and a symmetric one (usually re-aromatized complex)

were formed in a ratio of 2:1, respectively (Scheme 54). 1H NMR revealed hydrideic signals at -8.5

ppm indicative to trans-dihydrides. The aromatic region indicated aromatization of the pyridine ring (a

pattern of de-aromatized pyridine was not observed). A signal in the region between 5.5-6 ppm

indicated the presence of Si-H bonds. However, full characterization of the complexes was difficult.

Nevertheless the non symmetric complex was revealed by X-ray diffraction to be complex 67 which

was formed after double activation of diphenylsilane (Fig. 20; Table 19). We assume that the

symmetric system might be a product of oxidative addition of the Si-H bond of diphenylsilane without

involving the benzylic "arm" (Scheme 54).

N Ir

PtBu2

PtBu2

35

N Ir

PtBu2

PtBu2

H

H67

Ph2SiH2SiH

Si H

+ Product of Si-H activation with no involvment of the benzylic "arm".

25 oC ; 1 hr

Scheme 54

67

As was demonstaretd previously with complex 36, complex 35 is also capable of reacting with CO2 as

nucleophile on the benzylic "arm". CO2 activation in a nucleophilic manner is known.77 Several

examples are known such as urea synthesis, cyclic organic carbonate synthesis and the synthesis of

salicylic acid and its derivatives. Only the latter involves the attack of cabanion (sodium phenolate) on

CO2 , a process known as the "Kolbe-Schmidt process" (Scheme 55).

ONa

+CO2

COONaOH H+

COOHOH

O- OH

+ CO

O

OH

O

O OH

O

O

Scheme 55

When adding 1 eq. of CO2 into a C6D6 solution of 35, complexes 68 and 68a were formed (most

probably stereoisomers). Both complexes exhibited an A/B quartet in 31P{1H} NMR which are similar

in their chemical shifts. 1H NMR revealed two hydrideic signals at -24.9 ppm and -24.7 ppm might

correspond to hydride trans- to the pyridine ring and a hydride trans to the carboxylat's oxygen atom,

however, it could result from different stereo-isomers because of the chirality of the metal center and

the benzylic carbon. The hydrides resulted from vinylic activation of COE (Scheme 56). Signals at 6.0

ppm and at 6.5 ppm correspond to the vinylic protons of COE. Additional signals at 5.0 ppm and 5.1

ppm correspond to the benzylic protons next to the carboxylate moiety.

35

N Ir

PtBu2

PtBu2

N Ir

PtBu2

PtBu2

H

O

O

CO2

25 oC

H 68

N Ir

PtBu2

PtBu2

HO

OH 68a

+

May have stereoisomers: R,R; S,S; R,S; S,R

**

Scheme 56

In summary, we have shown that although an Ir(I) electron-rich complex was involved in these

reactions, the reactivity of the anionic de-aromatized PNP is by no means redundant, and in some

cases indispensable.

68

69

Figure 20: POV-Ray drawing of 67 at 50% probability level. Hydrogen atoms are omitted for clarity.For bond lengths and angles see Table 19.

Table 19: Selected bond lengths [Å] and bond angles [o] for 67 Selected bond Bond lengths (Å) Ir(1)- P(3) 2.3003(10) Ir(1)- P(2) 2.3119(10)

2.182(3) Ir(1)- N(1) 2.3430(11) Ir(1)- Si(6) 1.65(4) Ir(1)- H(1A) 1.54(5) Ir(1)- H(1B) 1.924(4) C(31)- Si(4)

Selected bonds Bond angles [deg] N(1)-Ir(1)- Si(6) 174.66(8) P(2)- Ir(1)-N(1) 79.89(8)

82.16(8) P(3)- Ir(1)-N(1) 160.83(15) P(2)- Ir(1)-P(3) 105.4 Si(4)- C(31)- H(31) 91.9(16) Si(6)- Ir(I)- H(1B)

70

4 Experimental

General procedures. All experiments with metal complexes and phosphine ligands

were carried out under an atmosphere of purified nitrogen in a Vacuum Atmospheres

glove box equipped with a MO 40-2 inert gas purifier or using standard Schlenk

techniques. All solvents were reagent grade or better. All non-deuterated solvents

were refluxed over sodium/benzophenone ketyl and distilled under argon atmosphere.

Deuterated solvents were used as received. All the solvents were degassed with argon

and kept in the glove box over 4A molecular sieves. Commercially available reagents

were used as received. 1H, 13C, 31P and 19F NMR spectra were recorded at 400, 100,

162 and 376 MHz, respectively, using a Bruker AMX-400 NMR spectrometer and at

500, 125 and 202 MHz, respectively, for 1H, 13C, 31P, using a Bruker Avance-500

NMR spectrometer. All spectra were recorded at 23 oC. 1H NMR and 13C{1H} NMR

chemical shifts are reported in ppm downfield from tetramethylsilane. 1

H NMR

chemical shifts were referenced to the residual hydrogen signal of the deuterated

solvents (7.15 ppm, benzene; 3.58 ppm and 1.73 ppm, tetrahydrofuran). In 13C{1H} NMR

measurements the signals of benzene-d6 (128.1 ppm), THF (67.4 ppm, 25.3 ppm) acetone-d6 (206 ppm,

29.8 ppm), dichloromethane (53.8 ppm) and Tol d8 ( 137.5 ppm, 128.9 ppm, 128 ppm, 125.2 ppm,

20.4 ppm).were used as a reference. 31P NMR chemical shifts are reported in ppm downfield from

H3PO4 and referenced to an external 85% solution of phosphoric acid in D2O. Abbreviations used in

the description of NMR data are as follows: br, broad; s, singlet; d, doublet; t, triplet; q, quartet, m,

multiplet, v, virtual.

Reaction of [Ir(COE)2(acetone)2][PF6] with tBuPNP (PNP = 2,6-Bis(di-tBuphosphinomethylene)pyridine; COE = cyclooctene). Preparation of

[Ir(tBuPNP)(COE)][PF6](1). An acetone solution (2 mL) of PNP (50 mg, 0.126 mmol) was added

dropwise to an acetone solution (2 mL) of [Ir(COE)2 (acetone)2][PF6]18 (85.2 mg, 0.126 mmol). Upon

addition of PNP the color turned dark purple-red. The mixture was stirred for an additional 2 min at

room temperature, than poured into pentane, causing precipitation of complex 1 as a pink-red solid.

The solid was separated by decantation and dried under vacuum, resulting in a quantitative yield of

complex 1.

[Ir(tBuPNP)(COE)][BArF] 1a To an acetone suspension (5ml) of [Ir(COE)2 µ-Cl]2 (200 mg, 0.223

mmol) was added 3 equiv of NaBArF(592 mg, 0.670 mmol). The slurry was stirred for 4 hrs at room

temperature until the color changed to red-purple. The solution was filtered through celite, the solvent

71

was evaporated and the residue was washed with pentane (15ml) and then washed with ether. The

pinkish solid was left under vacuum for one night resulting in 80% yield. 31P{1H} NMR (acetone d6):

44.00 (d, Jpp= 318.0 Hz, P-Ir-P), 49.00 (d, Jpp = 318.0 Hz, P-Ir-P), -150.00 (heptet , JFP = 713.0 Hz,

PF6). 1H NMR (acetone d6) 1.47 (dd, 5JPH = 1.8 Hz, 3JPH = 3.8 Hz), 1.42 (dd, 5JPH = 2.0 Hz, 3JPH = 4.3

Hz, 18H, P-C(CH3)3), 1.44-1.50(m , 10H , aliphatic hydrogens of COE), 2.55 (m, 2H, CH2-CH=CH),

4.07 (vt , JPH = 7.9 Hz, 4H, CH2-P), 4.20 (m, 2H vinylic hydrogens of COE), 7.87 (d, 3JHH = 7.8 Hz,

1H, PNP-aryl-H), 7.97 (d, 3JHH = 7.6 Hz, 1H, PNP-aryl H ), 8.25 (t, 3JHH = 7.7 Hz, 1H, PNP-aryl H). 19F NMR (acetone d6): -73 (d, 1JPF = 713.0 Hz, PF6). 13C{1H} NMR (acetone d6): 30.6 (m, PC(CH3)3),

36.2-36.5 (m, CH2P), 54 (s, 2H, CH=CH), 120 (dd, 3JPC = 7.4Hz, 5JPC = 10.1Hz, PNP-aryl C), 141.6 (s,

PNP-aryl C) , 164.3 (d, 2JPC = 13.0 Hz, PNP aryl -C). Barf signals: 1H NMR (acetone d6) 7.7 (s, 8H),

8.0(s, 4H); 19F NMR (acetone d6): -60 (s). Assignment of the signals was confirmed by DEPT.

Elemental analysis of 1 (counter-anion PF6-): Calcd for C31H57P3F6NIr: C, 44.17; H, 6.82. Found: C,

44.25; H, 6.76.

Reaction of [Ir(tBuPNP)(COE)][PF6] (1) with benzene. Formation of [Ir(tBuPNP)(H)(Ph)][PF6]

(2) . A solution (3mL) of complex 1 (15mg, 0.039 mmol) in benzene was heated at 60 oC for 1 hr

during which the color changed to orange. The solvent was evaporated and the orange solid was

washed with pentane and dried under vacuum overnight resulting in pure complex 2 in quantitative

yield. Compound 2 was obtained also by dissolving complex 1 in benzene and leaving it for 4 days at

room temperature. 31P{1H} NMR (hydride coupled, CD2Cl2): 54.00 (d, 2JHP = 10.0 Hz), -150.0 (heptet, 1JFP = 713 Hz, PF6). 1H NMR (CD2Cl2): -43.9 (vt, 2JPH = 12 Hz, 1H, H-Ir), 1.18 (dd, 5JPH = 6.9 Hz , 3JPH = 14.2 Hz, 18H, P-C(CH3)3), 3.90 (m, 4H, CH2-P), 6.80 (t, 2JHH = 7.3 Hz, 1H, aryl-H ), 6.93 (t, 2JHH = 6.2 Hz, 1H, aryl-H), 7.06 (t, 2JHH = 7.3 Hz, 1H, aryl-H), 7.32 (d, JHH = 7.6 Hz 2H, aryl-H), 7.7

(d, JHH = 7.8 Hz ,2H, H-PNP-aryl), 7.96 (t, JHH = 7.8 Hz, 1H, H-PNP-aryl). Assignment of signals was

confirmed by COSY. NOE effect was observed between hydride -43.9 ppm and protons at 7.32 ppm. 13C{1H} NMR (CD2Cl2): 27.9-29.6 (m, P-C(CH3)3), 36 (m, CH2P), 122.4 (m, PNP-aryl C3,5), 126.1-

136.4 (singlets, phenyl carbons), 139.6 (s, PNP-aryl, C4), 145 (broad triplet, Cipso), 163.9 (s, PNP-

aryl, C2,6). Assignment of the signals was confirmed by DEPT. Elemental analysis: Calc. for

C29H49P3F6NIr: C, 42.96; H, 6.09. Found: C, 44.93; H, 6.69.

Reaction of [Ir(tBuPNP)(COE)][PF6] 1 with m-xylene. Formation of [Ir(tBuPNP)(H)(m-

xylyl)][PF6] (3). solution (3mL ) of [Ir(PNP)(COE)][PF6] 1 (15 mg, 0.039 mmol) in m-xylene was

heated at 60 oC for an hour, during which an orange precipitate of [Ir(PNP)(H) (m-xylyl)][PF6] 3 was

formed in quantitative yield . The solid was washed with pentane and with ether followed by high

vacuum drying for one night. 31P{1H} NMR of the CD2Cl2 solution of 3 revealed one product . 31P{1H}

NMR (CD2Cl2): 53.7 (br s), -150.0 (heptet, 1JFP = 713 Hz , PF6). 1H NMR (CD2Cl2): -43.3 (vt, 2JPH =

12 Hz, 1H, H-Ir), 1.2 (m, P-C(CH3)3, 36H), 2.4 (s, 6H, aryl-CH3), 3.84 (m, 4H, CH2-P), 6.43 (s, aryl-

72

H), 6.90 (br s, aryl-H), 6.95 (br s, aryl-H) 7.67 (d, JHH = 7.8 Hz ,2H, H-PNP-aryl), 7.94 (t, JHH = 7.8

Hz, 1H, HPNP-aryl). Assignment of signals was confirmed by COSY. 13C{1H} NMR (CD2Cl2): 21 (s,

m-xylylCH3), 21.5 (s, m-xylyl-CH3) 28-30 (m, P-C(CH3)3), 37 (vt, 1JPC=9.3 Hz P-C(CH3)3) 38 (vt, 1JPC=9.3 Hz P-C(CH3)3), 39 (vt, 1JPC=11.1 Hz CH2P), 122.4 (m, PNP-aryl C3,5), 125.1- 135.3

(singlets, phenyl carbons), 139.6 (s, PNP-aryl, C4), 137 (broad triplet, Cipso), 163.9 (s, PNP-aryl,

C2,6). Assignment of signals was confirmed by DEPT. Elemental analysis: Calc. for C31H53P3F6NIr:

C, 44.38; H, 6.37. Found: C, 44.45; H, 6.31.

Synthesis of Ir(tBuPNP)(D)(C6D5)][PF6] (2a). Complex 2a was synthesized in two different routs:

(a) A solution (2 mL) of complex 1 (15mg, 0.039 mmol) in C6D6 was heated at 60 oC for 1 hr during

which the color changed to orange. The solvent was evaporated and the orange solid was washed with

pentane and dried under vacuum overnight resulting in pure complex 2a in quantitative yield. The 31P

NMR spectrum revealed a signal at 54 ppm. 2H NMR revealed a similar pattern as for complex 2. (b)

By an exchange reaction. A solution of complex 2 in C6D6 was heated at 50 oC for 4 hrs after which

the 31P NMR spectrum did not change and the signals of the hydride ligand and the aromatic protons in

the 1H NMR spectrum disappeared while appearing in the 2H NMR spectrum. Leaving a solution of

complex 2 in C6D6 at room temperature for 4 days resulted in a small exchange only.

Reaction of [Ir(tBuPNP)(H)(Ph)][PF6] (2) with CO.

Formation of [Ir(tBuPNP)(H)(Ph)(CO)][PF6] (4)

Into an acetone solution (3mL) of complex 2 (15mg, 0.039 mmol) was bubbled a small excess of CO

for 1 min during which the color changed to pale yellow. The solvent was evaporated and the pale

yellow solid was washed with pentane and dried under vacuum overnight resulting in pure complex 4

in quantitative yield. 31P{1H} NMR (CD2Cl2): 39 (s), -150.0 (heptet, 1JFP = 713 Hz, PF6). 1H NMR

(CD2Cl2): -7.6 (t, 2JPH = 12 Hz, 2H, H-Ir), 1.19 (m, P-C(CH3)3, 36H), 3.8 (m, 4H, CH2-P), 6.85 (br t,

2JHH = 7.3 Hz, 2H, H-aryl ), 6.91 (br t, 2H, H-aryl,), 7.67 (d, 2JHH = 7.0 Hz, 1H, H-aryl), 7.5 (d, JHH =

8.0 Hz, 2H, H-PNP-aryl), 7.78 (t, JHH = 7.5 Hz, 1H, H-PNP-aryl). 13C{1H} NMR (CD2Cl2): 29.5-31.1

(m, PC(CH3)3), 37.9 (vt , 1JPC = 9.3Hz P-C(CH3)3), 39.1 (vt 1JPC = 9.3 Hz , P-C(CH3)3), 41.5(vt,

1JPC =

11.0 Hz, P-C(CH3)3) 122.4 (m, PNP-aryl C3,5), 125.0- 135.8 (singlets, phenyl carbons), 139.6 (s,

PNP-aryl, C4), 150 (broad triplet, Cipso), 164.9 (s, PNP-aryl, C2,6), 186( br t, Ir-CO). Elemental

analysis: Calc. for C30H49P3F6NOIr: C, 42.95; H, 5.85. Found: C, 42.81; H, 6.05.

Reaction of [Ir(tBuPNP)(COE)][PF6] (1) with CO.

Formation of [Ir(tBuPNP)(CO)][PF6] (5) .

Into an acetone solution (3mL) of complex 1 (15mg, 0.039 mmol) was bubbled CO in small excess for

1 min during which time the color changed to yellow. The solvent was evaporated and the yellow solid

was washed with pentane and dried under vacuum overnight resulting in pure complex 5 in

73

quantitative yield. Slow evaporation of the acetone solution resulted in formation of yellow crystals

suitable for X-ray analysis. 31P{1H} NMR (CD2Cl2): 75.00 (s), -150.0 (heptet, 1JFP = 713 Hz , PF6). 1H

NMR (CD2Cl2): 1.15 (t, 3JPH = 14.2 Hz, 36H, P-C(CH3)3), 3.93 (m, 4H, CH2-P), 7.72 (d, JHH = 7.6 Hz,

2H, H-PNP-aryl), 8.0 (d, JHH = 7.8 Hz , 2H, H-PNP-aryl). 13C{1H} NMR (CD2Cl2): 27.9- 29.2(m, P-

C(CH3)3), 35.6 (t, 1JPC= 12.4 Hz, CH2P), 122.4 (m, PNP-aryl C3,5), 139.6 (s, PNP-aryl, C4), 166.9 (br

t, PNP-aryl, C2,6), 182 (br t, Ir-CO). Elemental analysis: Calc. for C24H43P3F6NOIr: C, 37.89; H, 5.70.

Found: C, 37.80; H, 5.76.

Reaction of [Ir(tBuPNP)(H)(Ph)][PF6] (2) with CH3CN. Formation of

[Ir(tBuPNP)(H)(Ph)(CH3CN)][PF6] (6)

To a CH2Cl2 solution (3mL) of complex 2 (15mg, 0.039 mmol) was added 1 equiv of acetonitrile

resulting in a color change to pale orange. The solvent was evaporated and the orange solid was

washed with ether and dried under vacuum overnight, resulting in pure complex 6 in quantitative yield.

Slow diffusion of pentane into THF solution of complex 6 allowed formation of orange crystals

suitable for X-ray analysis. 31P{1H} NMR (CD2Cl2): 37.97 (br s), -150.0 (heptet, 1JFP = 713 Hz, PF6).

1H NMR (CD2Cl2): -19.83 (br t,1H, H-Ir), 1.18 (m, 36H, P-C(CH3)3), 3.73 (m, 4H, CH2-P), 6.76 (br t, 2JHH = 7.3 Hz, 1H, H-aryl,), 6.85 (br t, 2H, H-aryl), 7.67 (d, 2JHH = 7.0 Hz, 2H, H-aryl), 7.5 (d, JHH =

8.0 Hz, 2H, H-PNP-aryl), 7.78 (t, JHH = 7.5 Hz, 1H, H-PNP-aryl). 13C {1H} NMR (CD2Cl2): 4 (s,

CH3CN) 28.5-30.1 (m, P-C(CH3)3), 36.9 (vt ,

1JPC=9.3 Hz P-C(CH3)3), 38.1 (vt 1JPC=9.3 Hz , P-

C(CH3)3), 39.5(vt, 1JPC=11.0Hz, P-C(CH3)3) 122.4 (m, PNP-aryl C3,5), 125.3- 135.6 (singlets, phenyl

carbons), 139.6 (s, PNP-aryl, C4), 125 (broad triplet, Cipso), 163.9 (s, PNP-aryl, C2,6).

Reaction of [Ir(tBuPNP)(H)(Ph)(CO)][PF6] (4) with anisole

When complex 4 (15 mg, 0.0178 mmol) was heated in anisole at 80 oC for 72 hrs no reaction took

place. Upon heating complex 4 in anisole at 110o C for 48 hrs, elimination of benzene occurred

forming complex 5 in quantitative yield. The same reaction was repeated in DMSO with the same

results.

Reaction of [Ir(tBuPNP)(H)(Ph)(CH3CN)][PF6] (6) with benzene d6

Heating a solution of 6 (15 mg, 0.0176 mmol) in benzene d6 at 70 oC for 48 hrs resulted in no

obsevable reaction. However, heating at 85 oC for the same period of time resulted in an exchange

reaction producing 6a. The hydride and aromatic signals disappeared and the corresponding 2H signals

appeared in 2H NMR.

Reaction of [Ir(tBuPNP)(COE)][PF6] (1) with benzene-h6 : benzene-d6. Determination of the

kinetic isotopic effect

A solution (2 mL) of [Ir(tBuPNP)(COE)][PF6] 1 (15 mg, 0.039 mmol) in benzene H6 : benzene d6

74

mixture in a molar ratio 1:1 was left at room temperature (25 oC) for 48hrs. The solution was

evaporated and re-dissolved in CD2Cl2. 1H NMR was measured with a delay of 25 sec to ensure full

spin relaxation. Two experiments were conducted, one was done without the use of internal standard

where the calibration was performed relative to the benzylic protons of the PNP ligand and the second

was performed using TMS as internal standard. Both experiments resulted in a 1:1 ratio of the deuterio

and protio complexes, indicating no kinetic isotope effect.

Reaction of [Ir(tBuPNP)(COE)][PF6] (1) with fluorobenzene. Formation of

[Ir(tBuPNP)(H)(C6H4F)][PF6] (7) A solution (2 mL) of [Ir(tBuPNP)(COE)][PF6] 1 (15 mg, 0.039

mmol) in fluorobenzene was heated at 50oC overnight, after which the solvent was evaporated and the

solid was washed with ether. 31P NMR of this solid revealed the formation of o-, m-and p- C-H

activated complexes 7a, b, c, giving rise to singlets at 55.2, 58, 52.3 ppm, in a ratio of approximately

2:2:1, respectively. Further heating at 50 oC for 48 hrs resulted in a mixture of 7a and 7c in a ratio

1.8:1 respectively. Prolonged heating at 80 oC for another 48 hrs resulted in a slightly different mixture

of the two isomers (2.3:1). For easier assignment of signals to the corresponding isomers, first the

mixture of two isomers was characterized (ortho- and para) using NOE and H-COSY. 31P{1H} NMR

(CD2Cl2) 7a: 55.2 (br d, 2JHP = 11.8 Hz, H-Ir-PC(CH3)3), 7b: 58.0 (br d,2JHP = 10.3 Hz, H-Ir-P-

C(CH3)3 ), 7c: 52.3 (broad). 1H NMR (800 MHz, CD2Cl2) 7a: -41.00 (br t, 2JHP = 11.5 Hz H-Ir-P),

1.18 (m, 36H, PC(CH3)3), 3.50-3.90 (m, 4H,CH2P), (dt, 3JHH = 8.0 Hz, 4JHH = 1 Hz, 1H, aryl-H), 6.85

(br-t, 1JHH = 8.0 Hz, 1H, aryl-H), 7.10 (dd, 3JHH = 1 Hz, 4JHH = 1.0 Hz, 1H, aryl -H),7.30 ( d, 3JHH = 7.0

Hz, 1H, aryl -H), 7.66 (d, 3JHH = 8.0 Hz, 2H, PNP-aryl H), 7.95 (t,3JHH = 8.0 Hz, 1H, PNP-aryl H).

NOE effect between the hydride at -41.0 ppm and proton at 7.10 ppm. 7b: -45.00 (br t, 2JHP = 10.0 Hz

), 1.18 (m, 36H, P-C(CH3)3), 3.50-3.90 (m, 4H, CH2P), 6.9 (m, 1H, aryl-H), 7.05(m, 1H, aryl-H), 7.25

(t, 3JHH =7.0 Hz, 1H, aryl -H), 7.35 ( br s, 1H, aryl -H), 7.7 (d, 3JHH = 8.0 Hz, 2H, PNP-aryl), 8.00 (t, 3JHH = 8.0 Hz, 1H, PNP-aryl). 7c: -42.5 (br, 1H),1.18 (m, 36H, P-C(CH3)3), 3.50-3.90 (m, 4H, CH2P),

7.25 (d, 3JHH = 7.0 Hz, 1H, aryl -H), 7.43 ( d, 3JHH =7.0 Hz, 1H, aryl -H), 7.5(d, 3JHH = 8.0 Hz, 2H, H-

PNP-aryl), 7.90 (t, 3JHH=8.0 Hz, 1H , PNP-aryl). Assignment of the signals was done by COSY. NOE

effect between the hydride at -42.5 ppm and protons at 7.25 ppm. Elemental analysis of 7: Calc. for

C29H48P3F7NIr: C, 42.02; H, 5.84. Found: C, 42.09; H, 5.81.

Reaction of [Ir(tBuPNP)(COE)][PF6] (1) with chlorobenzene. Formation of

[Ir(tBuPNP)(H)(C6H4Cl)][PF6] (8).

A solution of [Ir(PNP)(COE)][PF6] 1 (15 mg, 0.039 mmol) in chlorobenzene (2mL) was heated at 60 oC for 3 hrs. The solvent was evaporated and the resulting orange solid was washed consecutively with

pentane and ether, resulting in complex 8a in quantitative yield. Monitoring the reaction by 31P NMR

at 50 oC revealed after 12 min 10% conversion of 1, resulting in a ratio 8a:8b:8c of 4:2:1. Continued

heating of complex 1 for 1 hr at 50 oC resulted in formation of a mixture containing 60% of the ortho

75

activated chlorobenzene 8a, 30% of the meta 8b and 10% of the para activated one 8c. Further heating

of this mixture for 48 hrs resulted in a sole product, the ortho activated chlorobenzene complex 8a.

8a: 31P NMR (hydride coupled, CD2Cl2): 52.00 (d, 2JPH = 13.0 Hz). 1H NMR (CD2Cl2) -34.00 (t, 2JHP

= 13.8 Hz, 1H, H-Ir-P), 1.2 (m, 36H, P-C(CH3)3), 3.2-3.8 (m, 4H, CH2P), 6.65 (dd, 3JHH = 8.0 Hz, 4JHH

= 2.0 Hz, 1H, aryl-H), 6.91 (broad t, JHH = 8.0 Hz, 1H, aryl-H), 7.04 (dt, 3JHH =7.0 Hz, 4JHH = 1.0

Hz,1H, aryl -H), 7.3 ( d, 3JHH=7.0 Hz, 1H, aryl -H), 7.58 (d, 3JHH = 6.6 Hz, 2H, H-PNP-aryl), 7.92 (t, 3JHH = 6.6 Hz,1H, H-PNP-aryl). 13C {1H} NMR (400 MHz, CDCl3): 28.8-29.6 (m, P-C(CH3)3), 37.1-

38.7 (m, CH2P), 121.9-142.0 (singlets, PNP- aryl C3,5; C4 and phenyl) 163.5 (d, 2JPC = 12.0 Hz , PNP-

aryl C2,6) 163.3 (bs, Cipso). NOE was observed between the hydride at -34 ppm and the proton at

6.65 ppm. Selected 1H NMR data: 8b: -41( broad s, H-Ir, 1H), 7.1( m, 1H, aryl-H), 7.35(m, 2H, aryl-

H), 7.5( m, 1H, aryl-H). 7.58 (d, 3JHH = 6.6 Hz, 2H, H-PNP-aryl), 7.92 (t, 3JHH = 6.6 Hz, 1H, H-PNP-

aryl). NOE effect was observed between the hydride at -41 ppm and the protons 7.35 ppm. 8c: -44

(broad s, 1H, H-Ir), 7.0 (d, 3JHH = 6.0 Hz, 2H, aryl-H), 7.45 (d, 3JHH= 6.0 Hz, 2H, aryl-H), 7.58 (d, 3JHH

= 6.6 Hz, 2H HPNP-aryl), 7.92 (t, 3JHH = 6.6 Hz, lH, H-PNP-aryl). NOE was observed between the

hydride at -44 ppm and the proton at 7.45 ppm. 31P NMR (hydride coupled, CD2Cl2): 8c,8b: 53-53.5

(m, P-Ir-P). Elemental analysis of 8: Calc. for C29H48P3F6NClIr: C, 41.21; H, 5.72. Found: C, 41.31;

H, 5.63.

Reaction of [Ir(tBuPNP)(COE)][PF6] (1) with bromobenzene. Formation of

[Ir(tBuPNP)(H)(C6H5Br)][PF6] (9)

Complex 9 was prepared analogously to complex 8. The ortho activated bromobenzene complex 9a

amounted to 70% of the mixture upon disappearance of the starting complex 1 and the sole product

after continued heating at 60 0C for 3 hrs or longer. 9a: 31P NMR (hydride coupled, CD2Cl2) 49.0 (d, 2JPH = 11.0 Hz) 1H NMR (CD2Cl2) –29 (t, 2JPH = 11.0 Hz,1H, H-Ir-P ), 1.25 (vt, 3JPH = 7.0 Hz, 18H,

C(CH 3)3P), 1.29 (vt, 3JPH = 7.0 Hz, 18H, C(CH3)3P), 3.6-3.95 (m, 4H, CH2P), 6.73 (dd, 3JHH = 8.0 Hz,

1H, 4JHH = 1.0 Hz, H-aryl), 6.87 (br t, 3JHH = 8.0 Hz, 1H, 4JHH = 1.0 Hz, H-aryl), 7.09 (dt, 3JHH = 7.0

Hz, 1H, H-aryl), 7.25( br d, 3JHH = 7.0 Hz, 1H, H-aryl), 7.58( d, 3JHH = 8.0 Hz, 2H, H-PNP-aryl), 7.9 (t, 3JHH = 8.0 Hz, 1H, H-PNP-aryl). 13C{1H} NMR (CD2Cl2): 28.8-29.6 (m, P-C(CH3)3), 37-38.5 (m ,

CH2P) 120-142.3 (singlets, PNP-aryl C3,5; C4 and aryl) 164 (d, 2JPC = 12 Hz, PNP-aryl C2,6) 163.5

(br s, Cipso). NOE was observed between the hydride at -29 ppm and the proton at 7.25 ppm. Selected

NMR data for 9c: 1H NMR (CD2Cl2): -45 (br s, H-Ir, 1H), 7.27 (d, 3JHH = 5.0Hz, aryl-H, 2H), 7.52 (d, 3JHH = 5.0Hz, aryl-H, 2H). NOE was observed between the hydride at -45 ppm and the proton at 7.52

ppm. 9b: -42 (br s, H-Ir, 1H), 7.3 (m, aryl-H, 1H), 7.33 (m, aryl-H, 1H), 7.35 (m, aryl-H, 1H), 7.56 (m,

aryl-H, 1H) 7.58 (d, 3JHH = 6.6 Hz, 2H H-PNP-aryl),7.92 (t, 3JHH = 6.6 Hz, lH, H-PNP-aryl). NOE was

observed between the hydride at -42 ppm and the proton at 7.56 ppm. 9b,9c: 51-51.5(m, P-Ir-P).

Elemental analysis of 9: Calc. for C29H48P3F6NBrlIr: C, 39.15; H, 5.44. Found: C, 39.09; H, 5.39.

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Reaction of [Ir(tBuPNP)(COE)][PF6] (1) with anisole. Formation of [Ir(tBuPNP)(H)(o-

C7H8O)][PF6] (10). A solution (1mL) of [Ir(tBuPNP)(COE)][PF6] 1 (15 mg, 0.039 mmol) in anisole

was heated at 60 0C for 3 hrs. The solvent was evaporated and the resulting orange solid was washed

consecutively with pentane and ether, resulting in complex 10 in almost quantitative yield (90%).

Complexes resulting from metaand para activated anisole were observed in trace amounts. 31P{1H} NMR (hydride coupled, CD2Cl2): 56.60 (d, 2JPH =13.0 Hz). 1H NMR (CD2Cl2) -42.00 (t, 2JHP

= 13.0 Hz H-Ir-P), 1.2 (m, 36H, P-C(CH3)3), 3.55( s, CH3O; 3H),3.7-4.0 (m, 4H, CH2P), 6.4 (br d, 3JHH

=7.7 Hz, aryl-H), 6.7 (br t, 3JHH = 6.8 Hz, aryl-H), 7.25 (d, 3JHH =6.8 Hz, aryl -H), 7.6 ( br t, 3JHH =7.7

Hz, aryl -H), 7.65 (d, 3JHH = 7.7 Hz, 2H, H-PNP-aryl), 7.92 (t, 3JHH =7.7 Hz, 1H , H-PNP-aryl). 13C{1H}NMR (CD2Cl2): 27.8-29.9 (m, P-C(CH3)3), 35 (m, CH2P), 60 (m, CH3OPh), 122.0 (m, PNP-

aryl C3,5), 125.2- 135.6 (singlets, phenyl carbons), 138.5 (s, PNP-aryl, C4), 138 (broad triplet,

Cipso),162.0 (s, PNP-aryl, C2,6). Elemental analysis: Calc. for C30H51P3F6NOIr: C, 42.85; H, 6.11.

Found: C, 43.06; H, 6.03.

Lack of reaction of [Ir(tBuPNP)(H)(C6H4Cl)][PF6] (8a) with an anisol : chlorobenzene mixture

(1:1). A solution (1mL) of [Ir(tBuPNP)(H)(C6H4Cl)][PF6] (8a) in anisole and chlorobenzene 1:1 molar

ratio, was heated at 55 oC for 24 hrs. The resulting pale orange-like solid was washed consecutively

with pentane and ether resulting in complex 8a, the starting complex. 31P {1H} NMR, 1H NMR vide

supra.

Lack of reaction of [Ir(tBuPNP)(H)(o-C7H8O)][PF6] (10) with an anisole:chlorobenzene

mixture(1:1). A solution (1mL) of [Ir(tBUPNP)(H)(o-C7H8O)][PF6] (10) in anisole and chlorobenzene

1:1 molar ration, was heated at 55 oC for 24 hours. The resulting orange solid was washed

consecutively with pentane and ether resulting in complex 10, the starting complex. 31P{1H} NMR, 1H

NMR vide supra.

Reaction of [Ir(tBuPNP)(COE)][PF6] (1) with anisole : chlorobenzene : bromobenzene mixture

(1:1:1).A solution (1mL) of [Ir(tBuPNP)(COE)][PF6] (1) in anisole, bromobenzene and chlorobenzene

in 1:1:1 molar ratio was heated at 55 oC for 24 hours. The solvent was evaporated. 31P NMR revealed

three signals which correspond to the ortho- activated anisole 10a, ortho-activated chlorobenzene 8a,

and ortho-activated bromobenzene 9a (vide-supra) in a ratio of 35%, 32% and 33%, respectively. 1H

NMR revealed three hydride signals which corresponded to the three different complexes at a ratio

similar to that shown by 31P NMR. The hydrides were allowed to reach full relaxation (D1=45 sec). 31P

{1H} NMR, 1H NMR vide supra.

Reaction of [Ir(tBuPNP)(COE)][PF6] (1) with anisole:chlorobenzene:bromobenzene mixture

(1:1:1) A solution (1mL) of [Ir(tBuPNP)(COE)][PF6] (1) in anisole, bromobenzene and chlorobenzene

in 1:1:1 molar ratio was heated at 70 oC for 48 hours. The solvent was evaporated. 31P NMR revealed

77

four signals which correspond to the ortho- activated anisole 10a, the meta-, para-isomers of activated

chlorobenzene bromobenzene 8b,c, 9b,c and anisole 10b,c ortho-activated chlorobenzene 8a, and

ortho-activated bromobenzene 9a (vide-supra) in a ratio of 42%, 15%, 26% and 17%,respectively. 1H

NMR revealed four hydrideic signals which corresponded to the four different complexes at the ratio

similar to that shown by 31P NMR, the hydrides were allowed to reach full relaxation (D1= 45sec).

Reaction of [Ir(Ac)2(COE)2][PF6] (1) with iPrPNP. Formation of [Ir(iPrPNP)COE] [PF6] (11).

To a solution of [Ir(Ac)2(COE)2][PF6] (15 mg, 0.019 mmol) in Acetone (2mL) was added iPrPNP 2,6-

bis(diisopropylphosphinomethyl)pyridine (7.5 mg, 0.019 mmol). The color changed form orange to

purple-red immediately. The solution was poured into pentane (15 ml) resulting in a precipitation of

pink solid. The solvent was evaporated and the resulting pink solid was washed with ether resulting in

complex 11 in near quantitative yield.

11: 31P{1H} NMR (Ac d6): 38.00 (s), -160 ( septet, 1JFP = 711 Hz) . 19F{1H} NMR (Ac d6): 72.00 (d,

1JPF= 711 Hz ) 1H NMR (500MHz, C6D6) 1.20 (m, 12H, P-C(H)(CH3)2), 1.34 (m, 12H, P-

C(H)(CH3)2), 1.70 (m, 10H, COE, CH2CH2CH=CH), 2.39 ( m, 2H, CH2CH=CH) 2.55 (m, 4H, P-

C(H)(CH3)2), 3.86 (vt, 4H, 2JPH= 8 Hz, P-CH2Py), 3.94 (m, 2H, COE, CH=CH), 7.83 (d, 2H, 3JHH= 8

Hz Py-H) 8.15 (t, 1H, 3JHH= 8 Hz, Py-H) 13C{1H} NMR (Ac d6): 26.3 (s, COE), 29.6 (m,

PCH(CH3)2), 30.6 (m, PCH(CH3)2), 32 (s, CH2CH=CH), 37.2-38.5 (m, CH2P), 51.5 (s, CH=CH),

119 (s, Py-CH), 139.6 (s, Py-CH) , 167.3 (m, Py-CC). The structure was confirmed by DEPT, C-H

correlation experiment and 2D COSY NMR.

Reaction of [Ir(iPrPNP)COE] [PF6] (11) with benzene.

A benzene solution of [Ir(iPrPNP)COE] [PF6] 11 was heated to 60 oC for 48 hrs. No reaction was

observed.

Reaction of [Ir(iPrPNP)COE] [PF6] (11) with H2. Formation of [Ir(iPrPNP)(H)(H)] [PF6] (12)

To a solution (2mL) of [Ir(iPrPNP)COE] [PF6] 11 (12mg, 0.021 mmol) in acetone was bubbled excess

of H2 for 1 minute, during which the color changed to pale yello-orange. Addition of pentane to the

acetone solution precipitated complex 12 as a yellowish solid. Evaporation of traces of solvent allowed

separation of complex 12 in 85% yield. 12: 31P{1H} NMR (Ac d6): 52.00 (bs), -160 ( septet, 1JFP = 711

Hz) . 19F{1H} NMR (Ac d6): 72.00 (d, 1JPF= 711 Hz ). 1H NMR (500 MHz, Ac d6) -25( br m , 2H, Ir-H)

1.079 (m, 24H, P-CH(CH3)2), 2.10 (m, 2H, P-CH(CH3)2), 2.20 (m, 2H, P-CH(CH3)2), 3.93 (vt, 4H, 2JPH = 7.5 Hz, P-CH2Py), 7.63 (d, 2H, 3JHH = 7.75 Hz , Py-H), 7.95 (t, 1H, 3JHH = 7.7 Hz, Py-H). 13C{1H} NMR (Ac d6): 30.4 (m, PCH(CH3)2), 31.6 (m, PCH(CH3)2), 35.2 (m, CH2P), 121 (s, Py-

CH), 140.4 (s, Py-CH) , 166.3 (m, Py-CC). The structure was confirmed by DEPT, C-H correlation

experiment and 2D COSY NMR.

78

Reaction of [Ir(tBuPNP)COE] [PF6] (1) with H2. Formation of [Ir(tBuPNP)(H)(H)] [PF6] (13).

In a NMR tube fitted with septum, [(tBuPNP)Ir(COE)]PF6 (15 mg, 0.178 mmol) was dissolved in

acetone (2 mL). 3 mL of hydrogen were admitted to the reaction vessel. After shaking for 20 min, the

color of the reaction mixture changed from deep red to a pale orange. The solvent was removed under

vacuum, leaving an orange solid. The solid was washed with pentane and dried under vacuum to yield

(80%) of 13. 1H NMR (Ac d6, 500 MHz): -25.65 (t, 2H, 2JP-H =12.5 Hz, Ir-H), 1.28 (vt, 36 H, J=7.5

Hz, C(CH3)3), 3.94 (vt, 4H, J=3.5 Hz, CH2-Py), 7.68 (d, 2H, J )8.0 Hz, Py), 7.95 (t, 1H, J =7.5 Hz,

Py), 31P{1H} NMR (Ac d6): 75.62 (s, Ir-P), -143.87 (h, 1JF-P )709 Hz, PF6). Anal. Calcd for

C23H45F6IrNP3: C, 37.60; H, 6.17; N, 1.91. Found: C, 37.85; H, 6.23; N, 1.91.

Reaction of [Ir(C2H4)2(acetone)2][PF6]78 with tBuPNP.

Formation of [Ir(tBuPNP)(C2H4)][PF6] (14).

An acetone solution (2mL) of tBuPNP (50 mg, 0.126 mmol) was added dropwise to an acetone

solution (2mL) of [Ir(C2H4)2(acetone)2][PF6] (64.1 mg, 0.126mmol). Upon addition of PNP the color

turned red. The mixture was stirred for additional 2 mins at room temperature, than poured into

pentane, causing precipitation of complex 14 as red-brown solid. The solid was separated by

decantation and dried under vacuum, resulting in 80% yield of complex 14. 31P{1H} NMR (acetone

d6):

53.00 (s), -150.00 (heptet, JFP = 713.0 Hz, PF6). 1H NMR (acetone d6) 1.38 (vt, 3JPH = 5.7 Hz, 36H, P-

C(CH3)3), 4.07 (vt , JPH = 7.9 Hz, 4H, CH2-P), 3.70 (m, 4H C2H4), 7.87 (d, 3JHH = 7.8 Hz, 1H, Py-H),

7.97 (d, 3JHH = 7.6 Hz, 1H, PY-H ), 8.25 (t, 3JHH = 7.7 Hz, 1H, Py-H). 19F NMR (acetone d6): -73 (d, 1JPF = 713.0 Hz, PF6). 13C{1H} NMR (acetone d6): 30.6 (m, PC(CH3)3), 36.2-36.5 (m, CH2P), 50 (s,

2H, CH=CH), 120 (dd, 3JPC = 7.4Hz, 5JPC = 10.1Hz, PNP-aryl C), 141.6 (s, PNP-aryl C) , 164.3 (d, 2JPC

= 13.0 Hz, PNP aryl -C).

Reaction of [Ir(iPrPNP)COE] [PF6] (11) with D2. Formation of [Ir(iPrPNP)(D)(D)] [PF6] (15)

To a solution (2mL) of [Ir(iPrPNP)COE] [PF6] 11 (12mg, 0.021 mmol) in acetone was bubbled excess

of H2 for 1 minute, during which the color changed to pale yello-orange. Addition of pentane to the

acetone solution precipitated complex 15 as a yellowish solid. Evaporation of traces of solvent allowed

separation of complex 15 in 85% yield. 12: 31P{1H} NMR (Ac d6): 52.00 (bs), -160 ( septet, 1JFP = 711

Hz) . 19F{1H} NMR (Ac d6): 72.00 (d, 1JPF= 711 Hz ).

Reaction of [Ir(tBuPNP)(COE)][PF6] (1) with CH3CN. Formation of

[Ir(tBuPNP)(H)(COE)(CH3CN)][PF6] (16).

To an acetone solution (2mL) of 1 were added few drops of CH3CN. The solution turned immediately

pale orange. The mixture than was poured to pentane causing precipitation of complex 16 as pale

orange solid. Decantation of the solid followed by evaporation of traces of solvents resulted in the

79

known complex 16 in 76% yield. NMR data for this complex was reported earlier by Dominic

Hermann.(see reference 61).

Reaction of [Ir(tBuPNP)(COE)][PF6] (1) with LiCl. Formation of

[Ir(tBuPNP)(H)(COE)(Cl)][PF6] (16').

To an acetone solution (2mL) of 1 were added few mgs of LiCl. After 20 mins stirring at room

temperature the solution turned pale orange. The mixture than was poured to pentane causing

precipitation of complex 16' as pale orange solid. Decantation of the solid followed by evaporation of

traces of solovents resulted in the known complex 16' in 70% yield. NMR data for this complex was

reported earlier by Dominic Hermann.(see reference 61).

Reaction of [Ir(iPrPNP)(COE)][BF4] (11) with CH3CN. Formation of [Ir(iPrPNP)

(CH3CN)][BF4] (17).

To an acetone solution (2mL) of 11 were added few drops of CH3CN. During a period of 25 mins at

room temperature the solution turned orange. The mixture than was poured to pentane causing

precipitation of complex 17 as orange solid. Decantation of the solid followed by evaporation of traces

of solvents resulted in the known complex 17 in 73% yield. The same procedure was repeated in

acetonitrile as a solvent resulting in the same complex 17.

17: 31P{1H} NMR (CD3CN): 51. (s) 1H NMR (500 MHz, CH3CN) 1.15 (m, 12H, P-CH(CH3)2), 1.3

(m, 12H, P-CH(CH3)2), 2.4 (m, 4H, P-CH(CH3)2), 2.74 (br s, 3H, Ir-NCCH3), 3.3 (vt, 4H, 2JPH = 5.0

Hz, P-CH2Py), 7.32 (d, 2H, 3JHH = 7.0 Hz , Py-H), 7.85 (t, 1H, 3JHH = 7.0 Hz, Py-H), 13C{1H} NMR

(400 MHz, C6D6): 18.2(s, P-CH(CH3)2), 18.50(s, P-CH(CH3)2), 19.75 (s, P-CH(CH3)2), 35.50(m, P-

CH(CH3)2), 36.49(m, P-CH2Py), 95.87(dd, 5JPC= 4.5Hz, 4JPC= 4.8Hz, Py-CH), 115(t, 4JPC= 8.4Hz, Py-

CH), 122 (s, NCCH3) 131.67(s, Py-CH), 160.5 (t, 2JPC= 4.0Hz, Py-CC ).

Reaction of [Ir(tBuPNP)(COE)][BarF] (1a) with THF. Formation of

[Ir(tBuPNP)(H)(H)(=COC3H6)][BarF] (18). A solution (2mL) of [Ir(PNP)(COE)][Barf] 1a (15 mg,

0.039 mmol) in THF (2mL) was heated to 70oC for 1.5 hrs, after which the color changed to pale

yellow. The solvent was evaporated and the resulting white solid was washed with pentane, with ether

and then dried under vaccum, resulting in complex 18 in near quantitative yield.

18: 31P {1H}NMR (CD2Cl2): 62.00 (s), -156 (m, PF6). 1H NMR (400MHz, CD2Cl2) -7.71 (vt, 2JPH=13.22 Hz, H-Ir-H), 1.34 (vt, 36H, 3JPH=7.00 Hz, P-C(CH3)3), 1.97 ( q, 2H, 3JHH=7.71 Hz,

CH2CH2CH2), 2.99 (t, 2H, 2JPH=7.84 Hz), 3.60 (vt, 2H, 2JPH=3.94 Hz, PyCH2-P), 4.64 (t, 2H, 3JHH =

7.46 Hz, O-CH2CH2), 7.24 (t, 2H, 3JHH = 7.76Hz , Py-H), 7.60 (t, 1H, 3JHH = 7.76Hz , Py-H). 13C{1H}

NMR (400 MHz, CD2Cl2): 24.10 (s, CH2CH2CH2), 29.50(m, P-C(CH3)3), 36.40 (vt, 2JPC=12.80 Hz, P-

C(CH3)3, 41.22(vt, 2JPC=12.06 Hz CH2P), 65.55(s, 0-CH2CH2), 83.6(s, CH2C=Ir), 118.31 (m, Py-CH),

80

135.8(s, Py-CH), 161.65 (vt, 2JPC=3.20 Hz, Py-CC ) 264.10(t, 2JPC= 5.41Hz, Ir=C-O); The structure

was confirmed by DEPT, C-H correlation experiment ,2D COSY NMR and X-ray analysis.

Reaction of [Ir(PNP)(H)(H)(=COC3H6)][Barf] (18) with CO. Formation of

[Ir(PNP)(H)(CO)(COC3H6)][Barf] (19). To a solution of [Ir(PNP)(H)(H)(=COC3H6)][Barf] (18) (15

mg, 0.0095 mmol) in THF (2mL) was added 1 equivalent of CO gas, after which the color changed,

immediately, to yellow. The solvent was evaporated and the resulting yellowish solid was washed with

pentane, with ether and then dried under vaccum, resulting in complex 19 in quantitative yield. 31P {1H}NMR (CD2Cl2): 46.00 (s). 1H {31P}NMR (400MHz, CD2C12) -7.7 (vt, 2JPH=13.02 Hz, CO -Ir-

H), 1.2 (dd, 18H, 3JPH=9.30 Hz, 5JPH=4.40 Hz, P-C(CH3)3), 1.4 (dd, 18H, 3JPH=9.30 Hz, 5JPH=4.40 Hz,

P-C(CH3)3), 1.80 ( m, 2H, CH2CH2CH2), 1.90 (m, 1H, O-CH2CH2CH2), 2.2 (m, 1H, O-CH2CH2CH2),

3.20 (m, 2H, O-CH2CH2),), 3.60 (ddd, 1H, 2JHH=17.0 Hz, 2JPH=5.5Hz, 4JPH=1.7Hz, PyCH2-P), 3.80

(dd, 2H, 3JHH=8.0Hz, 3JHH=5.5Hz, O-CH2CH2), 3.78 (dd, 1H, 2JHH=17.0 Hz, 2JPH=3.0Hz, PyCH2-P),

4.09 (dd, 1H, 2JHH=17.0 Hz, 2JPH=5.0Hz, PyCH2-P), 4.15 (dd, 1H, 2JHH=17.0 Hz, 2JPH=6.9Hz, PyCH2-

P), 5.10 (ddd, 1H, 3JPH=4.8 Hz, 3JHH=11.0 Hz, 3JHH=9.8 Hz, Ir-CHCH2CH2), 7.57 (t, 2H, 3JHH = 7.7Hz ,

Py-H), 7.89 (t, 1H, 3JHH = 7.7Hz , Py-H). IR υCO= 2005 cm-1 The structure was confirmed by DEPT, C-

H correlation experiment ,2D COSY NMR

Reaction of [Ir(tBuPNP)(COE)][OTf] (1b) with THF. Formation of

[Ir(tBuPNP)(H)(OTf)(COC3H6)] (21), [Ir(tBuPNP)(H)(H)(=COC3H6)][OTf] (18b)

and[Ir(tBuPNP)(=COC3H6)][OTf] (22). Complex 1b (15 mg, 0.0178 mmol)was dissolved in THF

(2mL) and heated to 70oC for 12 hrs. Checking the solution by NMR after 1 hr revealed three

complexes 18b, 21 and 22 in ratio of 70% , 25% and 5% respectively. After 12 hrs only complex 22

was observed. Addition of pentane to the solution of 22 resulted in precipitation. Decantation of the

solid followed by evaporation yielded complex 22 as orange solid in 70% yield.

22: 31P {1H}NMR (CD2Cl2) : 67.00 (s). 1H NMR (250MHz, CD2Cl2) 1.28 (vt, 36H, 3JPH=6.85 Hz, P-

C(CH3)3), 1.96 ( q, 2H, JHH = 7.46Hz, CH2CH2CH2), 2.74 (t, 2H, 2JHH=7.66 Hz, Ir=CCH2CH2CH2),

3.62 (vt, 4H, 2JPH=3.51 Hz, PyCH2-P), 4.60 (t, 2H, 2JHH=7.23 Hz, O-CH2CH2), 7.48 (d, 2H, 3JHH =

7.68Hz , Py-H), 7.93 (t, 1H, 3JHH = 7.68Hz , Py-H). 13C{1H} NMR (400 MHz, CD2Cl2): 24.50 (s,

CH2CH2CH2), 29.00(m, P-C(CH3)3), 35.50 (vt, 2JPC=12.00 Hz, P-C(CH3)3, 42.12(vt, 2JPC=11.06 Hz

CH2P), 64.55(s, 0-CH2CH2), 84.6(s, CH2C=Ir), 117.31 (m, Py-CH), 137.8(s, Py-CH), 162.65 (vt,

2JPC=2.80 Hz, Py-CC ) 260.10(t, 2JPC= 6.21Hz, Ir =CO); The structure was confirmed by DEPT, C-H

correlation experiment ,2D COSY NMR.

Reaction of [Ir(tBuPNP)(COE)][OTf] (1b) with TBME. Formation of

[Ir(tBuPNP)(H)(OTf)(CH2OC4H9)](23), [Ir(tBuPNP)(H)(H)(=CHOC4H9)][OTf] (24)

and[Ir(tBuPNP)(=CHOC4H9)][OTf] (25).

Complex 1b (15 mg, 0.0178 mmol) was dissolved in TBME (2mL) and heated to 70oC for 12 hrs.

Checking the solution by NMR after 1 hr revealed three complexes 23, 24 and 25 in ratio of 45%, 45%

and 10% respectively. After 12 hrs only complex 25 was observed. Addition of pentane to the solution

of 25 resulted in precipitation. Decantation of the solid followed by evaporation yielded complex 25 as

orange solid in 70% yield. The spectrum after 1 hr: 31P {1H}NMR (CD2Cl2): 63.00 (s), 60.00 (s),

56.00 (s). 1H NMR (500MHz, CD2Cl2): -8.6 (t, 2JPH=11.85 Hz, H-Ir-H), 14.4 (t, 3JPH=6.45 Hz,

(H)(H)Ir=CHOtBu), -28.6 (t, 2JPH=11.15 Hz, H-Ir), 4.4 (m, Ir-CH2OtBu), 15.4 (t, 3JPH=6.3 Hz,

Ir=CHOtBu). 25: 31P {1H}NMR (CD2Cl2) : 56.00 (s). 1H NMR (500MHz, CD2Cl2) 1.25 (vt, 36H, 3JPH=5.95 Hz, P-C(CH3)3), 1.3 (s, 9H,O-(CH3)3), 3.52 (vt, 4H, 2JPH=4.50 Hz, PyCH2-P), 7.48 (d, 2H, 3JHH = 7.6Hz , Py-H), 7.91 (t, 1H, 3JHH = 7.6Hz , Py-H). 15.4 (t, 3JPH=6.3 Hz, Ir=CHOtBu). 13C{1H}

NMR (400 MHz, CD2Cl2): 24.50 (s, O-C(CH3)3),29.00(m, P-C(CH3)3), 35.50 (vt, 2JPC=12.00 Hz, P-

C(CH3)3, 42.12(vt, 2JPC=11.06 Hz CH2P), 67 (s, O-C(CH3)3), 117.31 (m, Py-CH), 137.8(s, Py-CH),

162.65 (vt, 2JPC=2.80 Hz, Py-CC ) 260 (t, 2JPC= 7.21Hz, Ir =CHO);

Reaction of Ir(PNP*)(COE) (35) with THF. Formation of Ir(PNP)(H)(H)( C=CHCH2CH3O) (26).

A solution of Ir(PNP*)(COE) 35 (15 mg, 0.021 mmol) in THF (2mL) was heated to 60oC for 2 hrs,

after which the color changed to pale yellow. The solvent was evaporated and the resulting off-white

solid was washed with cold pentane, and then dried under vaccum, resulting in complex 26 in near

quantitative yield. 26: 31P {1H}NMR (C6D6): 58.00 (s). 1H NMR (400MHz, C6D6) -9.12 (vt, 2H, 2JPH=14.70 Hz, H-Ir-H), 1.34 (vt, 36H, 3JPH=6.48 Hz, P-C(CH3)3), 2.30 ( m, 2H, CHCH2CH2), 3.37 (vt,

4H, 2JPH=3.55 Hz, PyCH2-P), 3.89 (t, 2H, 2JHH=8.77 Hz, O-CH2CH2), 4.11 (m, 1H, Ir-C=CHCH2),

7.07 (d, 2H, 3JHH = 7.72Hz , Py-H), 7.36 (t, 1H, 3JHH = 7.72Hz , Py-H). 13C{1H} NMR (400 MHz,

CD2Cl2): 29.66 (m, P-C(CH3)3), 34.57 (s, CHCH2CH2), 35.09 (m, P-C(CH3)3), 42.32(vt, 2JPC=10.06

Hz, CH2P), 69.58(s, 0-CH2CH2), 105.75 (t, 4JPC=2.44 Hz, CH=C-Ir), 118.32 (m, Py-CH), 133.15(s,

Py-CH), 147.00 (t, 2JPC=9.72 Hz, CH=Cipso-Ir) 163.32 (m, Py-CC ); The structure was confirmed by

DEPT, C-H correlation experiment ,2D COSY NMR.

Reaction of [Ir(tBuPNP)(COE)][BarF] (1a) with Anisole. Formation of

[Ir(tBuPNP)(H)(H)(=CHOC6H6)][BarF] (28) and [Ir(tBuPNP)(H)(CH2OC6H6)][BarF] (30). A

solution (2mL) of [Ir(PNP)(COE)][ BarF] 1a in Anisole (2mL) was heated to 80oC for 24 hrs, after

which the color changed to pale yellow after less then an hour complex 10a was the major product.

After 24 hrs there were three products 28, 30 and 10a. Precipitating the mixture with pentane a

redissolveing in CD2Cl2 revealed by NMR that 28 and 30 corresponds to the carben and alkyl hydride

forms respectively. According to 1H NMR a carbenic proton resonated at 14 ppm together with trans-

dihydrides at -7.8 ppm 28 and an hydrideic signal at -27 ppm corresponding to the alkyl hydride 30.

81

82

Reaction of [Ir(tBuPNP)(COE)][BarF] (1a) with 1,3,5 Trimethoxybenzene. Formation of

[Ir(tBuPNP)(H) (C6H3(OCH3)3)][BarF] (31).

A solid mixture of Trimethoxybenzene and complex 1a was heated to 70oC resulted in the melting of

trimethoxybenzene. Prolong heating for 4 hours resulted in orange solution of 31 as the sole product.

Washing with ether followed by evaporation under vacuum of the remaining solvent allowed the

isolation of 31 as orange solid in 90% yield. 31P {1H}NMR (C2Cl2): 56.90 (s). 1H NMR (400MHz,

C6D6) -40.12 (vt, H, 2JPH=14.00 Hz, H-Ir), 1.20 (vt, 36H, 3JPH=6.48 Hz, P-C(CH3)3), 3.40 ( s, 3H,

CH3-OPh), 3.60 (s, 3H, CH3-OPh), 3.75 (s, 3H, CH3-OPh), 3.4-3.8 (m, 4H, CH2-P), 7.3 (d, 2H, 3JHH =

7.72Hz , Py-H), 7.43(br s, BarF-H), 7.60(br s, BarF-H), 7.76 (t, 1H, 3JHH = 7.72Hz , Py-H).

13C{1H}NMR (CD2Cl2): 27.8-29.9 (m, P-C(CH3)3), 35 (m, CH2P), 55 (m, CH3OPh), 56.5 (m,

CH3OPh), 60 (m, CH3OPh), 97(s, Aryl-C), 122.0 (m, Py-C), 138.5 (s, Py-C), 139 (broad triplet,

Cipso), 162 (s, Caryl-O), 163.0 (s, Py-CC).

Reaction of [Ir(tBuPNP)(COE)][BarF] (1a) with 2,4,6 Trimethylanisole.

Formation of [Ir(tBuPNP)(H)(CH2OC6H2(CH3)3)][BarF] (33) and

[Ir(tBuPNP)(H)(H)(=CHOC6H2(CH3)3)] [BarF] (32).

A solution of 1a (15mg, 0.009 mmol) in 2,4,6 trimethylanisole (2mL) was heated to 60oC for 1.5 hrs

resulting in a mixture of three complexes. The two major complexes corresponded to 33 and 32 both

of them had the same concentration by NMR. Addition of pentane to there solution resulted in

precipitation of orange solid. The solution was then decanted and the solid was dried under vacuum

allowing the formation of orange solid 33 and 32 as a mixture. 31P{1H} NMR 63 (s), 80(br s). 1H NMR

-27.0 (t, 1H, 3JPH=12.14 Hz, H-Ir-CHOPh), 9-8.0 (t, 2H, 3JPH=10.28 Hz, H-Ir-H), 14.0 (t, 1H, 3JPH=7.01

Hz, Ir=CHOPh).

Reaction of [Ir(tBuPNP)(COE)][BarF] (1a) with 3,5 dimethylanisole.

Formation of [ (tBuPNP(CH3)2CH2)Ir(OC6H3(CH3)2)][BarF] (34).

A solution of 1a (15mg, 0.009 mmol) in 3,5 dimethylanisole (2mL) was heated to 60oC for 12 hrs

during which the color changed to orange. Addition of pentane to the solution of 34 resulted in

precipitation of orange solid. The solution was then decanted and the solid was dried under vacuum

allowing the formation of orange solid 34 in near 90% yield. 1P{1H}-17.5(d, 2Jpp=329 Hz, P-Ir-P),

32(d, 2Jpp=329 Hz, P-Ir-P). 1H{31P}1.0 (s, 3H, CH3C-P), 1.0 (s, 3H, CH3C-P), 1.35 (s, 9H, tBu-P), 1.35

(s, 9H, tBu-P), 1.56 (s, 9H, tBu-P), 1.63 (s, 3H, CH3C-P), 1.97 (d, 1H, 2JHH= 7.6Hz,

tBuPC(CH3)2CH2Ir), 2.17(s, 3H, CH3-Aryl), 2.25(s, 3H, CH3-Aryl), 3.83 (d, 1H, 2JHH= 17.54Hz,

CH2P), 3.87 (d, 1H, 2JHH= 7.6Hz, tBuPC(CH3)2CH2Ir), 3.95 (d, 1H, 2JHH= 17.54Hz, CH2P), 4.07 (d,

1H, 2JHH= 18.42Hz, CH2P), 4.26 (d, 1H, 2JHH= 18.42Hz, CH2P), 6.3(s, 1H, H-Aryl), 6.4(s, 1H, H-

83

Aryl), 6.5(s, 1H, H-Aryl), 7.27 (d, 2H, JHH = 7.5 Hz, Py), 7.73 (t, 1H, JHH = 7.5 Hz, Py). 13C {1H}

NMR (500 MHz, C6D6): 4(m, tBuPC(CH3)2CH2Ir), 22.5(s, CH3-Aryl), 22.8(s, CH3-Aryl), 25.0 (m,

CH3C-P), 27.0 (m, CH3C-P), 28 (m ,tBu-P), 29 (m ,tBu-P), 34.5 (d, 1JPC=23.40Hz, CH2P), 35.8 (d,

1JPC=23.40Hz, CH2P), 122.31 (d, 3JPC=9.40Hz, Py-CH), 123.31 (d, 3JPC=9.40Hz, Py-CH), 160.0 (s, Ir-

O-CAr), 165.3 (m, Py-CC), 167.3 (m, Py-CC).

Reaction of [Ir(tBuPNP)(COE)][PF6] (1) with tBuOK.

Formation of [Ir(tBuPNP*)COE] (35).

To a solution (2mL) of [Ir(tBuPNP)(COE)][PF6] 1 (15 mg, 0.039 mmol) in THF (2mL) was added tBuOK (4.4 mg, 0.039 mmol). The color changed to purple immediately. The solvent was evaporated

and the resulting purple solid was extracted with pentane and filtered through a cotton wool, resulting

in complex 35 in 89% yield.

35: 31P {1H}NMR (C6D6): 34.00 (A/B quartet, 2JPP =336.0Hz). 1H NMR (500MHz, C6D6) 1.20 (m,

18H, P-C(CH3)3), 1.42 (m, 18H, P-C(CH3)3), 1.65 (m, 10H, COE, CH2CH2CH=CH), 2.47( m, 2H,

CH2CH=CH) 2.8(d, 2H, 2JPH= 10Hz, P-CH2Py), 3.68 (m, 2H, COE, CH=CH), 3.75(vt, 1H, 2JPH= 6Hz,

P-CHPy), 5.4 (br d, 3JHH = 6Hz , Py-H), 6.35 (m, 2H, Py-H) 6.43 (m, 1H, Py-H) 13C{1H} NMR (500

MHz, C6D6): 27.3 (s, COE), 30(d, 2JPC=6.25 Hz, P-C(CH3)3), 30.4-31 (m, P-C(CH3)3), 33(s,

CH2CH=CH), 35(vt, 2JPC=9.3Hz, P-C(CH3)3), 36.7(m, CH2P), 37.4(m, P-C(CH3)3), 40.2(d,

2JPC=6.25Hz, CH2P) 71.5(dd, 2JPC=9.3Hz, P-CHPy), 96(s, COE, HC=CH), 115 (d, 2JPC= 12Hz, Py-

CH), 128.3(s, Py-CH), 128.55(s, Py-CH), 131.57(s, Py-CH), 159.5 (s, Py-CC ), 172.5(m, Py-CC) ;

15N-H correlation NMR in C6D6: the protons at 2.8ppm and 3.75ppm where correlated to a signal at

194ppm on 15N. The structure was confirmed by DEPT, C-H correlation experiment and 2D COSY

NMR.

Reaction of [Ir(PNP*)COE] (35) with benzene.

Formation of [Ir(PNP)(C6H5)] (36).

A benzene solution of [Ir(PNP*)(COE)] 35 was heated to 60 oC for 2 hrs after which the color changed

from purple-red to dark grey-violet. The solvent was evaporated resulting in complex 36 as greyish

solid in quantitative yield. Alternatively reacting complex [Ir(PNP)(H)(C6H5)]+PF6 2 (15 mg, 0.0185

mmol) with tBuOK ( 2 mg, 0.0185 mmol) at 25 oC resulted in complex 36 in near quantitative yield.

36: 31P{1H} NMR (C6D6): 55.00 (s). 1H NMR (500MHz, C6D6) 1.25 (vt, 36H, 3JPH= 6.5Hz, P-

C(CH3)3), 2.37(vt, 4H, 2JPH= 3Hz, P-CH2Py), 6.36 (d, 2H, 3JHH = 7.5Hz , Py-H), 6.90 (t, 1H, 3JHH =

7.0Hz, Aryl-H), 7.27 (t, 1H, 3JHH = 7.5Hz, Aryl-H), 7.65 (t, 1H, 3JHH = 7.5Hz , Py-H), 7.99 (d, 2H, 3JHH

= 7.0Hz, Aryl-H). 13C{1H} NMR (500 MHz, C6D6): 29.45(m, P-C(CH3)3), 36.20(vt, 2JPC=8.75Hz, P-

C(CH3)3), 39.60(vt, 2JPC=8.75Hz, CH2P), 118.32 (s, Py-CH), 120.28(vt, 2JPC=5.0Hz, Aryl-CH), 125.9(s,

Py-CH), 127.18(s, Aryl-CH), 144.9(s, Aryl-CH ), 153.5(vt, 2JPC=8.75Hz, Cipso) 161.90(vt, 2JPC=5.0Hz,

Py-CH); 15N-H correlation NMR in C6D6: the protons at 2.37 ppm where correlated to a signal at

84

277ppm on 15N. The structure was confirmed by DEPT, C-H correlation experiment and 2D COSY

NMR. Elemental analysis of 3; Anal. Calc. for C29H48P2NIr: C, 52.39; H, 7.28; Ir, 28.91; N, 2.11; P,

9.32.. found: C, 52.26; H, 7.21.

Reaction of [Ir(PNP)(H)(C6H5)][+PF6- ] (5) with tBuOK at -78oC.

Formation of [Ir(PNP*)(C6H6)(H)] (37) and [Ir(PNP)(C6H5)] (36).

To a THF solution of [Ir(PNP)(H)(C6H5)][+PF6- ] 5(15mg, 0.0185 mmole) at -78 oC was added tBuOK

(potassium tert-butoxide) (2 mg, 0.0185 mmol) the color immediately changed to dark brown. 31P

NMR revealed an A/B quartet implying the lack of a symmetry plane resulted from the deprotonation

of the benzylic protons. 1H NMR revealed a hydride at -47 ppm, typical for an hydride trans to a

vacant coordination site. Warming the solution to room temperature resulted after few seconds in clean

complex 36. 37: 31P {1H} NMR (THF d8, -78oC): 53.0(d, 2JPP = 336Hz, P-Ir-P), 43.0d, 2JPP = 336Hz, P-

Ir-P). 1H NMR (500MHz, THF d8, -78oC) -47.18 (vt,1H, 2JPH=12Hz, H-Ir ),1.00-1.50 (m, 36H, P-

C(CH3)3), 2.5-3.04(m, 2H, P-CH2Py), 3.70 (br t, 1H, P-CHPy), 5.67 (br d, 1H, Py-H), 6.45-6.85 (m,

5H, Aryl-H, Py-H), 8.01 (br d, 2H, Aryl-H). 13C{1H} NMR (500MHz, THF d8, -78oC): 13C{1H} NMR

(500MHz, CD2Cl2): 30.00 (m, P-C(CH3)3), 39.0(br m, CH2P), 65.30 (br m, CH-P), 95(br s, Py-CH),

112 (m, Aryl-CH), 122.4 (m, Aryl-CH), 123.3(m, Cipso), 127.6 (m, Aryl-CH), 131.3 (m, Py-CH), 144.7

(m, Aryl-CH),158.6(s, Py-CC), 170.3 (m, Py-CC). The structure was confirmed by DEPT, C-H

correlation experiment and 2D COSY NMR.

Reaction of [Ir(PNP)(D)(C6D5)][+PF6- ] (2a) with tBuOK at -78oC.

Formation of [Ir(PNP*)(C6D6)(D)] (37a) and [Ir(d1-PNP)(C6D5)] (36a).

To a THF solution of [Ir(PNP)(H)(C6H5)][+PF6- ] 2 (15mg, 0.0185 mmol) at -78 oC was added tBuOK

(potassium tert-butoxide) (2 mg, 0.0185 mmol) the color immediately changed to dark brown. 31P

NMR revealed an A/B quartet implying the lack of a symmetry plane resulted from the deprotonation

of the benzylic protons. 1H NMR no hydride was seen. 2H NMR do reveal a deuterid at -47 ppm. Upon

warming to room temperature complex 36 was observed. According to integration on 1H NMR, the

deuterid was placed on the benzylic position.

Reaction of [Ir(PNP)(H)(CO)(C6H5)][+PF6- ] (5) with tBuOK.

Formation of [Ir(PNP*)(C6H6)(H)(CO)] (38).

To a THF solution of [Ir(PNP)(CO)(H)(C6H5)][+PF6- ] 5 (15 mg, 0.0178 mmol) at 25 oC was added

tBuOK (potassium tert-butoxide) (2 mg, 0.0178 mmol) the color immediately changed to dark brown. 31P NMR revealed an A/B quartet implying the lack of a symmetry plane resulted from the

deprotonation of the benzylic protons. Complex 38 was also prerpared via reaction of 37 with one

equivalent of CO at -78 oC. 1H NMR revealed an hydride at -7.8 ppm typical for an hydride trans to a

CO ligand. 7: 31P {1H} NMR (250MHz, CD2Cl2): 45.5(d, 2JPP = 264.6Hz, P-Ir-P), 36.6(d, 2JPP =

85

264.6Hz, P-Ir-P). 1H NMR (250MHz, CD2Cl2) -7.81 (dd,1H, 2JPH=16.75Hz, 2JPH=16.87Hz, H-Ir

),1.14-1.40 (m, 36H, P-C(CH3)3), 3.1-3.2(m, 1H, P-CH2Py), 3.47-3.59 (m, 1H, P-CH2Py), 3.65(vt,

2JPH=4.32Hz, P-CHPy), 5.62 (d, 1H, 3JHH=6.50Hz, Py-H), 6.18 (d, 1H, 3JHH=8.80Hz, Py-H), 6.47 (m,

1H, Py-H), 6.76 (m, 3H, Aryl-H), 7.80 (m, 2H, Aryl-H). 13C{1H} NMR (500MHz, CD2Cl2): 30.00(m,

P-C(CH3)3), 39.10(m, CH2P), 65.33(m, CH-P), 97(d, 2JPC=15.52Hz, Py-CH),112(m, Aryl-CH),

122.4(m, Aryl-CH), 124.3(m, Cipso), 127.2(m, Aryl-CH), 132.3(m, Py-CH), 146.7(m, Aryl-

CH),158.3(s, Py-CC), 170.3(m, Py-CC), 184.2(br t, Ir-CO). IR υco=1986 cm-1.The structure was

confirmed by DEPT, C-H correlation experiment and 2D COSY NMR.

Reaction of [Ir(PNP)(C6H5)] (36) with CO. Formation of [Ir(PNP*)(C6H6)(H)(CO)] (38).

To a benzene solution of [Ir(PNP)(C6H5)] 3 (10 mg, 0.015 mmol), placed in an NMR tube, was

bubbled CO ( 0.34 ml, 0.015 mmol) at 25 oC. The color changed immediately to red-brown resulting

in complex 38.

Reaction of [Ir(PNP)(C6H5)] (36) with H2. Formation of [Ir(PNP)(C6H6)(H)(H)] (39).


bubbled H2 ( 0.3 ml, 0.015 mmol). The solution was shaken under H2 at 25 oC for 30 min until the

color changed to pale yellow. Evaporation of the solvent resulted in an almost colorless solid complex

39.

39: 31P{1H} NMR (C6D6): 54.00 (s). 1H NMR (500MHz, C6D6) -8.28 (vt,2H, 2JPH=12Hz, H-Ir-H

),1.29 (vt, 36H, 3JPH= 6.10Hz, P-C(CH3)3), 3.08(vt, 4H, 2JPH= 3.5Hz, P-CH2Py), 6.40 (d, 2H, 3JHH =

7.5Hz , Py-H), 6.76 (t, 1H, 3JHH = 6.8Hz, Aryl-H), 7.05 (t, 1H, 3JHH = 7.5Hz, Py-H), 7.12 (t, 2H, 3JHH =

7.5Hz , Aryl-H), 8.53 (d, 2H, 3JHH = 7.5Hz, Aryl-H). 13C{1H} NMR (400 MHz, C6D6): 29.31(m, P-

C(CH3)3), 35.45(vt, 2JPC=10.26Hz, P-C(CH3)3), 42.33(m, CH2P), 117.56-119.16 (s, Py-CH, Aryl-CH),

125.79-126.93(s, Py-CH, Aryl-CH), 130.64(t, 2JPC=8.75Hz, Cipso), 150.22(d, 2JPC=15.32Hz, Py-CH)

162.81(s, Py-CC). The structure was confirmed by DEPT, C-H correlation experiment and 2D COSY

NMR. NOE effect was seen between the hydrides at -8.82ppm and the protons at 8.53ppm.

Reaction of [Ir(PNP)(C6H5)] (36) with D2. Formation of [Ir((D1-PNP)(C6H6)(D)(H)] (39a).


bubbled D2 ( 0.3 ml, 0.015 mmol). The solution was shaken under D2 at 25 oC for 30 min until the

color changed to pale yellow. Evaporation of the solvent resulted in an almost colorless solid complex

39a. 1H and 31P NMR is identical to complex 39. However, incorporation of one deuterium to the benzylic

carbon was observed. The protons at 3.08 ppm were integrated to 3H with a 20 sec delay between

pulses. Also a hydride was observed integrated to one.

86

Reaction of [Ir(iPrPNP)COE] [PF6] (11) with KOtBu. Formation of [Ir(iPrPNP*)COE] (40). To a

solution (2 mL) of [Ir(iPrPNP)(COE)][PF6] 11 (15 mg, 0.019 mmol) in THF was added tBuOK (2.3

mg, 0.019 mmol). The color changed to purple immediately. The solvent was evaporated and the

resulting purple solid was extracted with pentane and filtered through a cotton wool, resulting in

complex 40 in 85% yield.

40: 31P{1H} NMR (C6D6): 29.43.00 (bs) 1H NMR (500 MHz, C6D6) 0.95 (m, 6H, P-CH(CH3)2), 1.20

(m, 6H, P-CH(CH3)2), 1.29 (m, 6H, P-CH(CH3)2), 1.39 (m, 6H, P-CH(CH3)2), 1.55 (m, 10H, COE,

CH2CH2CH=CH), 1.7 (m, 1H, P-CH(CH3)2), 1.78-1.98 ( m, 2H, P-CH(CH3)2), 2.10 ( m, 1H, P-

CH(CH3)2), 2.47 (m, 2H,CH2CH=CH), 2.6(vt, 2H, 2JPH = 5.0 Hz, P-CH2Py) 3.35 (m, 2H, COE,

CH=CH), 3.75 (vt, 1H, 2JPH = 5.0 Hz, P-CHPy), 5.54 (d, 2H, 3JHH = 5.0 Hz , Py-H), 6.55 (dd, 1H, 3JHH

= 5.0 Hz, 3JHH = 7.5 Hz Py-H), 6.55 (d, 1H, 3JHH = 7.5 Hz, Py-H). 13C{1H} NMR (400 MHz, C6D6):

17.56(s, P-CH(CH3)2), 17.76(s, P-CH(CH3)2), 18.0(s, P-CH(CH3)2), 18.54(s, P-CH(CH3)2), 19.75 (s,

P-CH(CH3)2), 25.41(m, P-CH(CH3)2), 27.3(s, COE), 32(s, COE), 35.70(m, P-CH(CH3)2), 37.39(m, P-

CH2Py) 45.(s, COE, HC=CH), 71.5(dd, 2JPC=9.3Hz, P-CHPy), 95.87(dd, 5JPC= 4.5Hz, 4JPC= 4.8Hz, Py-

CH), 115(dd, 4JPC= 8.4Hz, 3JPC= 8.9Hz, Py-CH), 131.67(s, Py-CH), 160.5 (t, 2JPC= 4.0Hz, Py-CC ),

175.14(m, Py-CC) The structure was confirmed by DEPT, C-H correlation experiment and 2D COSY

NMR.

Reaction of [Ir(tBuPNP*)COE] (35) with H2. Formation of [Ir(tBuPNP)(H)(H)(H)] (41).

To a pentane solution of [Ir(tBuPNP*)COE] (15 mg, 0.023 mmol) was added H2 in excess. The color

changed from red-purple to yellow during 20 min. The solution was evaporated resulting in a yellow

solid complex 41 in 88% yield. Some of complex 42 was observed but reacted further with time.

41: 31P{1H} NMR (C6D6): 75.6 (s). 1H NMR (500 MHz, C6D6) -21.15 ( tt , 1H, 2JPH = 14.40 Hz, 3JHH =

5.25 Hz), -10.52 ( dvt , 2H, 2JPH = 15.42 Hz, 3JHH = 6.29 Hz), 1.25 (m, 36H, P-C(CH3)3), 3.0 (br vt,

4H, 2JPH = 3.5 Hz, P-CH2Py), 6.54 (d, 2H, 3JHH = 7.7 Hz , Py-H), 6.75 (t, 1H, 3JHH = 7.7 Hz, Py-H). 13C

{1H} NMR (500 MHz, C6D6): 19.0(s, P-C(CH3)3), 35.49(m, P-CH2Py), 123.2(m, Py-CH), 132.67(s,

Py-CH), 163.7 (m, Py-CC ).

Reaction of [Ir(tBuPNP*)COE] (35) with H2. Formation of [Ir(tBuPNP)(H)(H)(COE)] (42).

To a pentane solution of [Ir(tBuPNP*)COE] (15 mg, 0.023 mmol) was added 1 eq .H2 into the NMR

tube. The color changed from red-purple to yellow during 35 min. The solution was evaporated

resulting in a yellow solid complex 42 in 80% yield (by NMR). Some of complex 41 was observed

however at lower temperature complex 41 was formed in excess. Complex 42 was synthesized also

from complex 1 and NaEt3BH. Addition of NaEt3BH toluene solution 1 eq. to a pre-cooled (-30) THF

87

solution of 1 resulted, (after warming to room temperature) in near quantitative yield (by NMR) of

complex 42. Some traces of complex 41 and 35 were observed. Evaporation under vacuum of the

solution mixture allowed formation of yellowish-brown solid 42.

42: 31P{1H} NMR (C6D6): 50.61 (s). 1H NMR (500 MHz, C6D6) -8.7 (br t, 1H, Ir-H), -8.9 (br t, 1H, Ir-

H), 1.55 (m, 36H, P-C (CH3)3), 1.88 (m, 2H, CH2CH2CH2CH=C), 1.95 (m, 2H, CH2CH2CH2CH=CH),

2.08 (m, 2H, CH2CH2CH2C=CH), 2.12 (m, 2H, CH2CH2CH2C=CH), 2.45 (m, 2H,

CH2CH2CH2CH=C), 3.0 (br vt, 4H, 2JPH = 3.25 Hz, P-CH2Py), 3.50 (m, 2H, CH2CH2CH2C=CH), 6.48

(d, 2H, 3JHH = 7.65 Hz , Py-H), 6.55 (dd, 1H, 3JPH = 8.25 Hz, 3JHH = 6.75 Hz, CH2CH2CH2CH=C), 6.85

(t, 1H, 3JHH = 7.65 Hz, Py-H). 13C {1H} NMR (500 MHz, C6D6): 28.6 (s, P-C (CH3)3), 30.45 (s, P-C

(CH3)3), 38.6 (vt, JPC = 8.65 Hz, P-C (CH3)3), 39.69 (vt, 1JPC = 8.65 Hz, P-CH2Py), 71(m, CH=C-Ir),

101(m, CH=C-Ir),119.2(m, Py-CH), 135.67(s, Py-CH), 161.5 (m, Py-CC ).

Reaction of [Ir(iPrPNP*)COE] with H2. Formation of [Ir(iPrPNP)(H)(H)(H)] (43).

To a pentane solution of [Ir(iPrPNP*)COE] (15 mg, 0.023 mmol) was added H2 small excess. The

color changed from red-purple to yellow almost immediately. The solution was evaporated resulting in

a yellow solid complex 43 in near quantitative yield (by NMR).

43: 31P{1H} NMR (C6D6): 57.70 (s). 1H NMR (500 MHz, C6D6) -20.25 ( tt , 1H, 2JPH = 14.40 Hz, 3JHH

= 5.25 Hz), -10.32 ( dvt , 2H, 2JPH = 16.72 Hz, 3JHH = 5.29 Hz), 1.20 (m, 12H, P-CH(CH3)2), 1.35 (m,

12H, P-CH(CH3)2), 1.8 (m, 4H, P-CH(CH3)2), 3.0 (br vt, 4H, 2JPH = 3.5 Hz, P-CH2Py), 6.54 (d, 2H, 3JHH = 7.7 Hz , Py-H), 6.75 (t, 1H, 3JHH = 7.7 Hz, Py-H), 6.55 (d, 1H, 3JHH = 7.5 Hz, Py-H). 13C{1H}

NMR (500 MHz, C6D6): 18.6(s, P-CH(CH3)2), 19.44(s, P-CH(CH3)2), 23.4(m, P-CH(CH3)2), 35.49(m,

P-CH2Py), 126.2(m, Py-CH), 130.67(s, Py-CH), 165.5 (m, Py-CC ).

\

Reaction of Ir(tBuPNP)(C6H6) (36) with O2. Formation of Ir(PNP*)(C6H6)(OH)(44)

To a benzene solution (1mL) of Ir(PNP)(C6H6) (15 mg, 0.023) 0.5 equivalent of O2 (0.25 mL) was

injected. Immediate color change, from dark purple to green, was observed resulting in the formation

of Ir(PNP*)(C6H6)(OH) complex 3 in 90% yield. The reaction was performed under dark conditions

and was repeated with the addition of 30 equiv of BHT radical inhibitor.

44: 31P{1H} NMR (C6D6): 26.05-41.12 (A/B quartet, 2JPP = 337.0 Hz ). 1H NMR (500 MHz, C6D6) -3.5

( br ,1H, Ir-OH), 0.6 ( d, 9H, 3JPH = 13.07 Hz , P-C(CH3)3), 0.79 ( d, 9H, 3JPH = 13.07 Hz , P-C(CH3)3),

1.06 ( d, 9H, 3JPH = 12.50 Hz , P-C(CH3)3), 1.13 ( d, 9H, 3JPH = 12.50 Hz , P-C(CH3)3), 2.72 (dd, 1H,

2JHH = 16.47 Hz , 3JPH = 9.00 Hz, P-CH2Py), 2.82 (ddvd, 1H, 2JHH = 16.47 Hz , 3JPH = 10.00 Hz, 5JPH =

3.00 Hz, P-CH2Py), 3.51 ( vdd, 1H, 3JPH = 4.5 Hz, 5JPH = 3.00 Hz, P-CHPy), 5.55 (d, 1H, 3JHH = 6.5 Hz ,

Py-H), 5.77 (d, 1H, 3JHH = 8.0 Hz, Py-H), 5.99 (d, 1H, 3JHH = 9.0 Hz, Py-H), 6.26 (dd, 1H, 3JHH = 7.5

Hz, 3JHH = 9.0 Hz, Aryl-H), 6.31 (m, 1H, Aryl-H), 6.41 (m, 2H, Aryl-H), 7.99 (m, 1H, Aryl-H). 13C

88

{1H} NMR (500 MHz, C6D6): 28.8-30.3 (m, P-C(CH3)3), 33.8 (d, 1JPC=23.45Hz, CH2P), 36.0-37.1 (m,

P-C(CH3)3), 61.8 (d, 1JPC=62.75Hz,

CHP), 92.94(m, Py-CH), 110.27( m, Ir-Cipso), 112.31 (m, Py-CH), 122.1-128.5 (m, Aryl-CH), 132.1

(m, Py-CH), 139.23 (m, Aryl-CH), 159.2 (m, Py-CC), 174.11 (m, Py-CC) 15N-1H correlation

spectroscopy revealed a signal correlated to the benzylic protons at -150 ppm. The structure was

confirmed by DEPT, C-H correlation experiment and 2D COSY NMR. ESI-MS: m/z (%) 682.64

(100%), 680.64 (65%), 681.7 (20%), 683.67 (35%), 684.7(5%).

Reaction of Ir(tBuPNP*)(C6H6)(OH)(44) with CO2. Formation of Ir(tBuPNP)(C6H6)(CO3) (45).

To a benzene solution (2 mL) of 44 (15 mg, 0.022 mmol) was added 1 eq. of CO2. Immediate change

of color from green to violet was observed. NMR revealed mainly complex 45 however some traces of

impurities were seen too. The solution was then evaporated under vacuum and the solid was washed

with pentane. Finally, the solid was left under vacuum for one night resulting in violet solid in 70%

yield.

37: 31P {1H}NMR (THF d8, -78 oC): 15.0(s) 1H NMR (CD2Cl2) 1.15 (m, 18H, P-C(CH3)3), 1.2 (m,

18H, P-C(CH3)3), 3.5-3.9 (m, 4H, CH2P), 6.6 (br d, 3JHH =7.5 Hz, aryl-H), 6.8 (br t, 3JHH = 6.8 Hz,

aryl-H), 7.35 (d, 3JHH =6.8 Hz, aryl -H), 7.6 ( br t, 3JHH =7.7 Hz, aryl -H), 7.90 (t, 3JHH =7.7 Hz, Py-H),

8.05 (d, 3JHH = 7.7 Hz, 2H, Py-H). 13C{1H}NMR (CD2Cl2): 22.8-25.9 (m, P-C(CH3)3), 35 (m, CH2P),

122.0 (m, PNP-aryl C3,5), 125.2- 135.6 (singlets, phenyl carbons), 138.5 (s, PNP-aryl, C4), 138 (broad

triplet, Cipso),160 (s, CO3), 165.0 (s, PNP-aryl, C2,6).

Reaction of [(tBuPNP)Rh(H)(H)][BF4](56) with tBuOK. Formation of (tBuPNP)Rh(H)(46)

[(tBuPNP)Rh(H)(H)] (15.0 mg, 0.03 mmol) was dissolved in THF (0.5 mL), 1 equivalent of tBuOK

(3.7 mg, 0.03 mmol) was subsequently added resulting in color change to brownish. The THF was

removed under vacuum, and the brown solid was extracted with pentane. The pentane solution was

filtered through Teflon filter and the pentane was removed by vacuum, yielding a brown solid in 80%

yield. Complex Rh-H was also synthesized through the reaction of RhPNP* with 1 equivalent of H2 in

pentane. The yield was similar but PNPRh(H)(H)(H) was also formed in 15% yield. 31P{1H} NMR

(C6D6) 83.3 (d, 2P, 1JRh-P = 153 Hz). 1H NMR (C6D6, 400 MHz) -12.50 (vq, JPH = 20.3 Hz, JRh-H =

40.1 Hz, 1H, Rh-H), 1.5 (vt, 36H, JPH = 6.4 Hz, C(CH3)3), 2.95 (vt, 4H, J = 2.8 Hz, CH2-Py), 6.60 (d,

2H, J = 7.6 Hz, Py-H), 7.07 (t, 1H, J = 7.6 Hz, Py-H).

Reaction of (tBuPNP)Rh(H) (46) with O2. Formation of (tBuPNP)Rh(OH) (47).

(PNP)Rh(H) (15.0 mg, 0.03 mmol) was dissolved in THF(0.5 mL), 1 equivalent of O2 was

subsequently added to an NMR tube. The tube was shaken for half an hour, (under dark) resulting in

brighter red solution. The THF was removed under vacuum, yielding a pink solid in 80% yield. The

experiment was repeated in the presence of radical inhibitor BHT, with no apparent change in rate.

89

47: 31P{1H} NMR (C6D6) d 57.60 (d, 2P, 1JRh-P = 157 Hz). 1H NMR (C6D6, 400 MHz) -2.03 (br s, 1H,

Rh-OH), 1.45 (vt, 36H, J = 6.3 Hz, C(CH3)3), 2.49 (vt, 4H, J = 3.3 Hz, CH2), 6.22 (d, 2H, J = 7.5 Hz,

Py), 6.97 (t, 1H, J = 7.5 Hz, Py).

Reaction of [Ir(tBuPNP)(COE)][BarF] (1a) with 3,5 dimethyl-bromobenzene. Formation of

[Ir(CH2CH3PNPtBu)COE] (48).

A solution (2mL) of [Ir(PNP)(COE)][BarF] 1a (15 mg, 0.009 mmol) in 3,5 dimethyl-bromobenzene

(2mL) was heated to 70 oC for 12 hrs during which the color changed to orange. Addition of pentane

to 48 solution resulted in precipitation of orange-yellow solid. The solid was left under vacuum for one

night resulting in orange solid 48 in 90% yield. 31P{1H} NMR -17.5(d, 2Jpp=329 Hz, P-Ir-P), 32(d, 2Jpp=329 Hz, P-Ir-P). 1H{31P} NMR 1.0 (s, 3H, CH3C-P), 1.0 (s, 3H, CH3C-P), 1.35 (s, 9H, tBu-P),

1.35 (s, 9H, tBu-P), 1.56 (s, 9H, tBu-P), 1.63 (s, 3H, CH3C-P), 1.97 (d, 1H, 2JHH= 7.6Hz, tBuPC(CH3)2CH2Ir), 3.83 (d, 1H, 2JHH= 17.54Hz, CH2P), 3.87 (d, 1H, 2JHH= 7.6Hz, tBuPC(CH3)2CH2Ir), 3.95 (d, 1H, 2JHH= 17.54Hz, CH2P), 4.07 (d, 1H, 2JHH= 18.42Hz, CH2P), 4.26 (d,

1H, 2JHH= 18.42Hz, CH2P) 7.27 (d, 2H, JHH = 7.5 Hz, Py), 7.73 (t, 1H, JHH = 7.5 Hz, Py). 13C {1H}

NMR (500 MHz, C6D6): 4(m, tBuPC(CH3)2CH2Ir), 25.0 (m, CH3C-P), 27.0 (m, CH3C-P), 28 (m ,tBu-

P), 29 (m ,tBu-P), 34.5 (d, 1JPC=23.40Hz, CH2P), 35.8 (d, 1JPC=23.40Hz, CH2P), 122.31 (d,

3JPC=9.40Hz, Py-CH), 123.31 (d, 3JPC=9.40Hz, Py-CH), 138.0 (m, Py-CH), 165.3 (m, Py-CC), 167.3

(m, Py-CC).

Reaction of [Rh(Ac)2(COE)2][BF4] with tBuPNP. Formation of [Rh(tBuPNP)N2] [BF4] (49).

To a benzene suspension of [Rh(Ac)2(COE)2][BF4] was added dropwise a benzene solution of tBuPNP, upon which the color turned to red-brown. Then N2 was bubbled through the solution for 30

min. Addition of pentane to the red-brown suspension resulted in precipitation. The pentane was than

decanted and traces of pentane and benzene were evaporated under vacuum, resulting in complex 49

as brownish solid, in 85% yield. IR νRh-NN= 2155 cm-1. 31P{1H} NMR (C6D6) 71.4 (d, 1JRh-P =125 Hz,), 1H NMR (C6D6) 1.11 (vt, 36H, JHP= 6.9Hz C(CH3)3), 3.65 (vt, 4H, JHP = 4.2 Hz, P-CH2-Py), 7.35 (t,

1H, JHH = 7.8 Hz, Py-H), 7.95 (d, 2H, JHH = 7.8 Hz, Py-H). 13C{1H} NMR (C6D6, 500 MHz) 29.15 (s,

C(CH3)3), 29.33 (s, C(CH3)3), 35.17 (t, 1JP-C = 8.8 Hz, C(CH3)3), 35.80 (m, C(CH3)3), 38.50 (t, 1JP-C =

8.8 Hz, CH2Py), 131.31 (s, Py-C), 141.00(s, Py-C), 143.0 (s, Py-C), 165.80 (vt, 2JP-C = 2.5 Hz, Py-

CCH2).

Reaction of [(tBuPNP)Rh(N2)][BF4] (49) with C6H5Br. Formation of

[(tBuPNP)Rh(C6H5)(Br)][BF4](50).

[(PNP)Rh(N2)][BF4] (20 mg, 0.03 mmol) was heated under argon, in bromobenzene (2 mL) to 120 oC

for 12 hrs. The solution turned to a bright orange color. Pentane was added to the bromobenzene

90

solution resulting in precipitation of complex 4 as orange solid. Traces of pentane were removed under

vacuum resulting in an orange solid 4 in a yield of 80%.

50: 31P{1H} NMR (C6D6) 40.4 (d, 1JRh-P = 97.4 Hz,), 1H NMR (C6D6) 1.06 (vt, 18H, JHP= 7.0Hz

C(CH3)3)), 1.28 (vt, 18H, JHP= 7.0Hz C(CH3)3)), 3.85 (dvt, 2H, JHP = 4.5 Hz, JHH = 18.0 Hz, P-CH2-

Py), , 4.41 (dvt, 2H, JHP = 4.5 Hz, JHH = 18.0 Hz, P-CH2-Py), 5.69 (br d, 1H, JHH = 8.0 Hz, Aryl-H),

6.56 (m, 2H, Py-H & Aryl-H), 6.74 (t, 1H, JHH =7.0 Hz, Aryl-H), 8.02 (t, 1H, JHH = 8.0 Hz, Py-H),

8.38 (d, 2H, JHH = 8.0 Hz, Py-H), 8.49 (br d, 1H, JHH = 8.0 Hz, Py). 13C{1H} NMR (C6D6, 500 MHz)

29.15 (s, C(CH3)3), 29.33 (s, C (CH3)2), 35.17 (t, 1JP-C = 8.8 Hz, C(CH3)3), 35.80 (m, C(CH3)3), 38.50

(t, 1JP-C = 8.8 Hz, CH2Py), 123.10 (m, Ar), 124.80 (br s, Ar), 125.30 (br s, Ar), 129.60 (br s, Ar),

131.31 (s, Py-C), 141.00(s, Py-C), 142.0 (dt, Ar1JRh-C = 36 Hz, 2JP-C = 7.4 Hz, Rh-C), 143.0 (s, Ar),

165.80 (vt, 2JP-C = 2.5 Hz, Py-CCH2).

Reaction of [Rh(Ac)2(COE)2][BF4] with iPrPNP. Formation of [Rh(iPrPNP)COE] [BF4] (51).

To an acetone solution of [Rh(Ac)2(COE)2][BF4] was added drop wise an acetone solution of iPrPNP,

the color turned to red-brown. Addition of pentane to the red-brown acetone solution resulted in

precipitation of red-brown solid. The pentane was than decanted and traces of pentane were evaporated

under vacuum resulting in complex 51 as brownish solid, in 90% yield.

51: 31P{1H} NMR (acetone-d6): 45.83 (d, JRhP = 131.4 Hz). 1H NMR (250 MHz, acetone-d6): 1.19(dd,

12H, JPH=6.8 JHH=7.0 Hz, CH(CH3)2)), 1.33 (dd, 12H, JPH=7.6 JHH=7.0 Hz, CH(CH3)2)), 1.85 – 1.40

(m, 8H, COE, -(CH2)2CH2-CH=CH-), 2.52-2.25 (m, 8H, COE- CH2-CH=CH-CH2 + CH(CH3)2.

(1H{31P} NMR exhibits overlapped m signal and hept. centered at 2.35 (JPH=7.0 Hz, CH(CH3)2)) 3.72

(vt, JPH=4.0 Hz, 4H, CH2-P), 4.40 (m, 2H, COE, CH=CH), 7.67 (d, 2H, 3JHH=7.7 Hz, PNP-aryl H),

7.99 (t, 1H, 3JHH=7.7 Hz, PNP-aryl H). 13C{1H} NMR (63 Hz, acetone-d6): 17.41 (s, CH(CH3)2)),

19.08 (bs, CH(CH3)2)), 25.34 (vt, JPC=9.5 Hz, CH(CH3)2)), 26.96 (s, COE, CH2), 32.01 (s, COE, CH2),

35.20 (t, JPC=4.1 Hz, COE, CH2-CH=CH), 35.94 (vt, JPC=9.8 Hz, CH2-P), 72.76 (d, JRhC=12.1 Hz,

COE, CH=CH), 122.01 (vt, JPC=5.0 Hz PNP aryl-CH), 140.83 (s, PNP aryl-CH), 164.53 (bs, PNP

aryl-C).

Reaction of [Rh(iPrPNP)COE] [BF4] (51) with Benzylbromid. Formation of

[Rh(iPrPNP)(CH2C6H5)(Br)] [BF4] (52).

To a THF solution (2mL) of 51 was added excess of benzyl bromide. The reaction mixture was stirred

at room temperature for 2 hr resulting in complex 52. The solution was saturated with pentane causing

precipitation of brown solid. 52 was left for one night under vacuum resulting in a brown solid in 70%

yield. 31P{1H} NMR (C6D6) d 54.00 (d, 1JRh-P = 98.9 Hz).1H NMR (C6D6, 400 MHz); 1.31 (m, 12H,

CH(CH3)2), 1.45 (m, 12H, CH(CH3)2), 2.45-2.55 (m, 2H, CH(CH3)2), 2.65-2.70 (m, 2H, CH(CH3)2),

3.76 (vt, 2H, 2JHH = 18.2 Hz, 3JPH=6.6Hz, CH2P), 4.05 (vt, 2H, 2JHH = 18.2 Hz, 3JPH=6.6Hz, CH2P),

5.06 (dt, 2H, 2JHH = 13.0 Hz, 3JPH=8.5Hz, Rh-CH2Ph), 7.08 (t, 2H, 3JHH = 7.0 Hz, Aryl-H), 7.35 (m, 1H,

Aryl-H), 7.58 (d, 2H, 3JHH = 7.4 Hz, Py-H), 7.65 (m, 2H, Aryl-H), 7.85 (t, 1H, 3JHH = 7.4 Hz, Py-H).

91

13C{1H} NMR (C6D6, 400 MHz) 165.68 (t, 2JP-C = 14 Hz, Py-C), 140.8 (s, Py-C), 123.30 (s, Py-C),

38.7 (s, CH2P), 18.6(s, P-CH(CH3)2), 19.44(s, P-CH(CH3)2), 30.3(s, CH(CH3)3), 29.11 (s, C(CH3)3),

25.3 (dt, 1JRh-C = 30 Hz, 2JP-C = 13 Hz, RhCH2Ph), 23.4(m, P-CH(CH3)2).

Reaction of [Rh(tBuPNP)N2] [BF4] (51) with CH2Cl2.

Formation of [Rh(tBuPNP)(CH2Cl)(Cl)] [BF4] (53).

A CH2Cl2 solution (2mL) of 51 was stirred at 25 oC for 14 hrs resulting in complex 53. The solution

was saturated with pentane causing precipitation of brown solid, then the solid was washed with ether

twice. 53 was left for one night under vacuum resulting in a brown solid in 80% yield.

53: 31P{1H} NMR (C6D6) d 49.50 (d, 1JRh-P = 99.8 Hz).1H NMR (C6D6, 400 MHz); 1.41 (vt, 18H, 3JPH

= 6.0 Hz, C(CH3)3), 1.60 (vt, 18H, 3JPH = 6.0 Hz, C(CH3)3), 3.96 (vt, 2H, 2JHH = 19.0 Hz, 3JPH=6.5Hz,

CH2P), 4.16 (vt, 2H, 2JHH = 19.0 Hz, 3JPH=6.5Hz, CH2P), 5.76 (dt, 2H, 2JHH = 12.0 Hz, 3JPH=8.5Hz, Rh-

CH2Cl), 7.68 (d, 2H, 3JHH = 7.4 Hz, Py-H), 7.90 (t, 1H, 3JHH = 7.4 Hz, Py-H). 13C{1H} NMR (C6D6,

400 MHz) 165.68 (t, 2JP-C = 14 Hz, Py-C), 140.8 (s, Py-C), 123.30 (s, Py-C), 44.3 (dt, 1JRh-C = 30 Hz,

2JP-C = 13 Hz, RhCH2Cl), 38.7 (s, CH2P), 37.38 (s, C(CH3)3), 35.52 (s, C(CH3)3), 30.3(s, C(CH3)3),

29.11 (s, C(CH3)3).

Reaction of [(tBuPNP)Rh(N2)][BF4] (49) with CO. Formation of [(tBuPNP)Rh(CO)][BF4] (54).

To an acetone solution (2mL) of 49 was bubbled at 25 oC CO gas resulting in immediate color change

to yellow. The solution was saturated with pentane causing precipitation of yellow solid, then the solid

was washed with ether twice. 54 was left for one night under vacuum resulting in a yellow solid in

90% yield. IR νRh-CO= 1986 cm-1. 31P{1H} NMR (Aceton d6) 75.0 (d, 1JRh-P = 124 Hz,), 1H NMR

(Aceton d6) 1.13 (vt, 36H, JHP= 6.8Hz C(CH3)3), 3.75 (vt, 4H, JHP = 4.3 Hz, P-CH2-Py), 7.28 (t, 1H,

JHH = 7.8 Hz, Py-H), 7.85 (d, 2H, JHH = 7.8 Hz, Py-H). 13C{1H} NMR (Aceton d6, 500 MHz) 29.15 (s,

C(CH3)3), 29.23 (s, C(CH3)3), 35.14 (t, 1JP-C = 8.8 Hz, C(CH3)3), 35.65 (m, C(CH3)3), 38.50 (t, 1JP-C =

8.8 Hz, CH2Py), 131.0 (s, Py-C), 141.00(s, Py-C), 143.0 (s, Py-C), 165.80 (vt, 2JP-C = 2.5 Hz, Py-

CCH2), 188 (m, Rh-CO).

Reaction of [(tBuPNP)Rh(N2)][BF4] (49) with H2. Formation of [(tBuPNP)Rh(H)(H)][BF4] (55).

[(PNP)Rh(N2)][BF4] (20 mg, 0.03 mmol) was dissolved in aceton (2 mL) at room temperature. 0.3 ml

of H2 were bubbled through the solution (0.9 mmol), during which the color changed to yuellow.

Pentane was then added causing precipitation of yellow solid complex 55. Complex 55 was then left

under vacuum for 12 hrs resulting in yellow powder. Yield: (80%). 31P{1H} NMR (Aceton d6) 83.9 (d, 1JRh-P = 113 Hz). 1H NMR (Aceton d6, 400 MHz) -20.70 (br m, 2H,

Rh-H), 1.4 (vt, 36H, JPH = 6.3 Hz, C(CH3)3), 3.4 (vt, 4H, J = 2.8 Hz, CH2-Py), 7.20 (d, 2H, J = 7.6 Hz,

Py-H), 7.87 (t, 1H, J = 7.6 Hz, Py-H). 13C{1H} NMR (C6D6, 500 MHz) 168.70 (dt, 1JRh-C = 34 Hz, 2JP-C

= 14 Hz, Rh-C), 143.25 (s, Py), 124.30 (s, Py), 36.78 (s, CH2), 35.24 (s, C(CH3)3), 29.21 (s, C(CH3)3).

92

Reaction of [(iPrPNP)Rh(COE)][BF4] (51) with H2. Formation of [(iPrPNP)Rh(H)(H)][BF4] (56).

[(iPrPNP)Rh(COE)][BF4] (20 mg, 0.03 mmol) was dissolved in aceton (2 mL) at room temperature.

0.3 ml of H2 were bubbled through the solution (0.9 mmol), during which the color changed to

yuellow. Pentane was then added causing precipitation of yellow solid complex 56. Complex 56 was

then left under vacuum for 12 hrs resulting in yellow powder. Yield: (83%). 31P{1H} NMR (Aceton d6) 74.3 (d, 1JRh-P = 110.3 Hz). 1H NMR (Aceton d6, 400 MHz) -19.30 (br m,

2H, Rh-H), 1.2 (m, 12H, CH(CH3)2), 1.32 (m, 12H, CH(CH3)2), 2.44(m, 4H, CH(CH3)2), 3.3 (vt, 4H, J

= 2.9 Hz, CH2-Py), 7.19 (d, 2H, J = 7.3 Hz, Py-H), 7.76 (t, 1H, J = 7.3 Hz, Py-H). 13C{1H} NMR

(C6D6, 500 MHz) 168.70 (dt, 1JRh-C = 34 Hz, 2JP-C = 14 Hz, Rh-C), 143.25 (s, Py), 124.30 (s, Py), 36.78

(m, CH2P), 35.24 (s, CH(CH3)2), 29.21 (s, CH(CH3)2), 19.41 (s, CH(CH3)2), 17.08 (bs, CH(CH3)2).

Reaction of [(tBuPNP)Rh(N2)][BF4] (49) with tBuOK. Formation of (tBuPNP*)Rh(N2)(57).

[(PNP)Rh(N2)][BF4] (20 mg, 0.03 mmol) was dissolved in THF (2 mL) at room temperature. tBuOK

(3.7 mg, 0.03 mmol) was added and the solution turned to a bright red color. The solvent was removed

under vacuum. The remaining red residue was extracted into pentane (10 mL) and filtered through a

teflon syringe filter. The pentane was then removed under vacuum to give a bright red solid. Yield:

(70%). 31P{1H} NMR (C6D6) 63.98 (A-B pattern of doublets, 1P, 2JPP = 269 Hz, 1JRh-P= 131 Hz), 67.50

(A-B pattern of doublets, 1P, 2JPP = 270 Hz, 1JRh-P= 131 Hz) 1H NMR (C6D6) 6.26 (m, 1H, Py), 6.09

(d, 1H, JHH = 8.7 Hz, Py), 5.36 (d, 1H, JHH = 6.6 Hz, Py), 3.46 (d, 1H, JHP= 3.9 Hz, P-CH-Py), 3.01 (d,

2H, JHP = 8.1 Hz, P-CH2-Py), 1.56 (m, 36H, C(CH3)3). IR (thin film) N-N = 2122 cm-1. Anal. Calcd for

C23H42N3P2Rh: C, 52.57; H, 8.06; N, 8.00.

Reaction of [(iPrPNP)Rh(COE)][BF4] (51) with tBuOK. Formation of (iPrPNP*)Rh(COE)(58).

[Rh(iPrPNP)COE] [BF4] (15.0 mg, 0.023 mmol) was dissolved in THF (0.5 mL), 1 equiv of tBuOK

(2.5 mg, 0.023 mmol) was subsequently added resulting in color change to brown-red. The THF was

removed under vacuum, and the brown solid was extracted with pentane. The pentane solution was

filtered through Teflon filter and the pentane was removed by vacuum, yielding a brown solid in 85%

yield. 31P{1H} NMR (500 MHz, C6D6): A/B quartet 31.83 (dd, JRhP = 150.4 Hz, JPP = 303 Hz),

45.25(dd, JRhP = 150.4 Hz, JPP = 303 Hz), 1H NMR (250 MHz, acetone-d6): 1.19-1.43(m, 24H,

CH(CH3)2), 1.95 – 1.48 (m, 8H, COE, -(CH2)2CH2-CH=CH-), 2.52-2.25 (m, 8H, COE- CH2-CH=CH-

CH2 + CH(CH3)2, 2.5(m, CH(CH3)2) 2.82 (vt, JPH=4.0 Hz, 2H, CH2-P), 4.20 (m, 2H, COE, CH=CH),

5.67 (m, 1H, Py-H), 6.37 (m, 1H, Py-H), 6.87 (m, 1H, Py-H). 13C{1H} NMR (C6D6): 16.71 (s,

CH(CH3)2)), 18.8 (bs, CH(CH3)2)), 25.0 (vt, JPC=9.5 Hz, CH(CH3)2)), 26.96 (s, COE, CH2), 32.01 (s,

COE, CH2), 35.20 (t, JPC=4.1 Hz, COE, CH2-CH=CH), 35.94 (vt, JPC=9.8 Hz, CH2-P), 62.56 (d,

JRhC=12.1 Hz, COE, CH=CH), 122.01 (vt, JPC=5.0 Hz Py-CH), 138.83 (s, PNP aryl-CH), 160.53 (bs,

Py-CC).

93

Reaction of (iPrPNP*)Rh(COE) (58) with C6H6. Formation of (iPrPNP*)Rh(C6H5)(59).

A benzene solution of 1 was heated at 80 oC for 12 hrs a color change from red-brown to brown, was

observed resulting in complex 2 in 60% yield after work-up. Work-up included, evaporation of the

benzene solution followed by pentane washing and filtration. The filtrate was extracted with ether

resulting in complex 2. 31P{1H} NMR (500 MHz, C6D6): 41.83 (d, JRhP = 170.4 Hz). 1H NMR (500 MHz, C6D6): 1.10(dd,

12H, JPH=6.5 JHH=7.0 Hz, CH(CH3)2)), 1.20 (dd, 12H, JPH=6.6 JHH=7.0 Hz, CH(CH3)2), 1.9 (m, 4H,

CH(CH3)2), 2.67 (vt, JPH=4.0 Hz, 4H, CH2-P), 6.42 (d, 2H, 3JHH=7.7 Hz, Py-H), 7.00 (m, 3H, Aryl-H

& Py-H), 7.42 (t, 1H, 3JHH=7.0 Hz, Aryl-H), 8.00 (m, 2H, Aryl-H). 13C{1H} NMR (63 Hz, acetone-

d6): 17.41 (s, CH(CH3)2), 19.08 (bs, CH(CH3)2), 25.34 (t, JPC=9.5 Hz, CH(CH3)2), 35.94 (vt, JPC=9.8

Hz, CH2-P), 119.01 (s, Aryl-C), 121.0 (s, Py-C), 131.31 (s, Py-C), 135.41 (m, Rh-Cipso) 142.53 (s,

Aryl-C), 164.53 (bs, Py-C).

Reaction of (tBuPNP*)Rh(N2) (57) with C6H6. Formation of (tBuPNP)Rh(C6H5) (60).

A benzene solution of (tBuPNP*)Rh(N2) was heated to 80 oC for 12 hrs after which the color changed

to brown, resulting in complex (tBuPNP)Rh(C6H5), 61%. :

54: 31P{1H} NMR (C6D6) d 59.40 (d, 2P, 1JRh-P = 173 Hz).1H NMR (C6D6, 400 MHz); 1.26 (vt, 36H, J

= 6.0 Hz, C(CH3)3), 2.86 (vt, 4H, J = 3.0 Hz, CH2), 6.46 (d, 2H, J = 7.5 Hz, Py), 6.98 (t, 2H, J = 7.5

Hz, Aryl-H, Py-H), 7.26 (t, 2H, J = 7.5 Hz, Aryl-H), 8.17 (d, 2H, J = 7.5 Hz, Aryl-H). 13C{1H} NMR

(C6D6, 500 MHz) 168.70 (dt, 1JRh-C = 32 Hz, 2JP-C = 14 Hz, Rh-C), 161.68 (s, Ar), 142.55 (s, Ar),

131.21 (s, Ar), 123.30 (s, Ar), 118.97 (s, Ar), 116.83 (s, Ar), 37.38 (s, CH2), 35.12 (s, C(CH3)3), 29.11

(s, C(CH3)3). Anal. Calcd for C29H48NP2Rh: C, 60.52; H, 8.41; N, 2.43. Found: C, 60.51; H, 8.31; N,

2.44.

Reaction of (tBuPNP)Rh(H)(46) with H2O. Formation of (tBuPNP)Rh(H)(H)(OH) (61). 31P{1H} NMR (Acetone d6) 65.3 (d, 1JRh-P = 105 Hz). 1H NMR (Acetone d6, 400 MHz) -17 (br m, 2H,

Rh-H), -1.2 (br m, 1H, Ir-OH), 1.2 (br m, 18H, C(CH3)3), 1.32 (m, 18H, C(CH3)3), 2.94-3.3 (m, 4H,

CH2-Py), 7.17 (d, 2H, J = 7.3 Hz, Py-H), 7.66 (t, 1H, J = 7.3 Hz, Py-H). 13C{1H} NMR (C6D6, 500

MHz) 163.70 (dt, 1JRh-C = 30 Hz, 2JP-C = 12 Hz, Rh-C), 143.25 (s, Py), 124.30 (s, Py), 36.78 (m,

CH2P), 35.24 (s, CH(CH3)2), 29.21 (s, CH(CH3)2), 19.41 (s, CH(CH3)2), 17.08 (bs, CH(CH3)2).

Reaction of (tBuPNP)Rh(H)(46) with H2. Formation of (tBuPNP)Rh(H)(H)(H)(62).

[(tBuPNP)Rh(H)] (15.0 mg, 0.03 mmol) was dissolved in THF (0.5 mL), 1 ml of H2 (0.1 mmol) was

subsequently bubbled through the solution resulting in color change to yellow-brown. The THF was

removed under vacuum, yielding a yellow-brown solid in 80% yield. 31P{1H} NMR (C6D6) 81.9 (d,

2P, 1JRh-P = 153 Hz). 1H NMR (C6D6, 400 MHz) -10.50 (ddt, JHH = 7.6 Hz, JPH = 19.3 Hz, JRh-H = 40.1

94

Hz, 2H, Rh-H), -17.50 (m, 1H, Rh-H), 1.3 (vt, 36H, JPH = 6.4 Hz, C(CH3)3), 2.77 (vt, 4H, J = 2.8 Hz,

CH2-Py), 6.80 (d, 2H, J = 7.6 Hz, Py-H), 7.17 (t, 1H, J = 7.6 Hz, Py-H). 13C{1H} NMR (C6D6, 500

MHz) 168.70 (dt, 1JRh-C = 32 Hz, 2JP-C = 14 Hz, Rh-C), 142.55 (s, Py), 123.30 (s, Py), 37.38 (s, CH2),

35.12 (s, C(CH3)3), 29.11 (s, C(CH3)3).

Reaction of [Ir(tBuPNP)C6H5](36) with MeI.

Formation of [Ir(tBuPNP)(C6H5)(CH3)][I-](63).

To a benzene solution of [Ir(tBuPNP)C6H5] (15 mg, 0.023 mmol) at 25 oC was added MeI in small

excess. The color changed from grey-violet to brown-yellow during 2-5 mins. The solution was

evaporated resulting in a red-brown solid. 31P NMR revealed two complexes 63 in 90% yield (by

NMR). The two complexes have a similar NMR pattern in 1H NMR but two different Ir-CH3 groups

implying an isomeric structures.

63: 31P{1H} NMR (C6D6): 24.60 (br s), 34.00 (br s). 1H NMR (500 MHz, Tol d8) 0.867 (br vt, 18H, P-

C (CH3)3), 0.899 (br vt, 18H, P-C (CH3)3), 1.05 (br vt, 18H, P-C (CH3)3), 1.08 (br vt, 18H, P-C

(CH3)3), 1.58 (br t, 3H, Ir-CH3), 2.42 (br t, 3H, Ir-CH3), 3.46 (br d, 2JHH= 17 Hz, 2H, P-CH2Py), 4.33

(br d, 2JHH= 17 Hz, 2H, P-CH2Py), 5.7 (br d, 1H, 3JHH = 8.00 Hz, Aryl-H), 6.40 (br t, 1H, 3JHH = 7.20

Hz, Aryl-H), 6.56 (br t, 3JHH = 7.50 Hz, 1H, Aryl-H), 6.68 (br t, 3JHH = 7.00 Hz, 1H, Aryl-H), 7.14 (br t, 3JHH = 7.50 Hz, 1H, Aryl-H), 7.34 (br t, 3JHH =8.00 Hz, 1H, Aryl-H), 7.60 (br signal, 1H, Aryl-H), 8.00

(br t, 3JHH = 7.00 Hz, 1H, Py-H), 8.05 (br t, 3JHH = 7.00 Hz, 1H, Py-H), 8.85 (br d, 3JHH = 7.50 Hz, 2H,

Py-H), 9.07 (br d, 3JHH = 7.50 Hz, 2H, Py-H), 13C{1H} (500 MHz, Tol d8): -12.5 (m, Ir-CH3), -4.0 (m,

Ir-CH3), 30 (m, P-C(CH3)3), 36 (m, CH2P), 62.5(d, 1JPC= 62.0 Hz, P-CHPy) 97.5 (d, 4JPP= 8.8 Hz, Py-

CH), 110 (m, Cipso), 111.6 (d, 3JPP= 24.0 Hz, Py-CH), 121-131 (s, Aryl-C & Py-C), 158.8 (s, Py-

CCH2P), 171 (br m, Py-CC). The structure was confirmed by DEPT, C-H correlation experiment and

2D COSY NMR

Reaction of [Ir(tBuPNP)(C6H5)(CH3)][I-](63) with CO. Formation of

[Ir(tBuPNP)(C6H5)(CH3)(CO)][I](64).

To a THF solution of [Ir(tBuPNP)(C6H5)(CH3)][I-] (15 mg, 0.019 mmol) was added CO (0.4 mL,

0.019 mmol). The color changed from reddish to pale red-yellow almost immediately. The solution

was evaporated under vacuum and the resulting in a yellow-orange solid was precipitated with pentane

and decanted. Than the pentane was evaporated under vacuum resulting in a red-yellow solid. 31P

NMR revealed one singlet. 65: 31P{1H} NMR (C6D6): 30.5 (s), 1H NMR (500 MHz, Tol d8) 1.2 (br vt,

18H, P-C (CH3)3), 1.25 (br vt, 18H, P-C (CH3)3), 1.3 (br vt, 18H, P-C (CH3)3), 1.35 (br vt, 18H, P-C

(CH3)3), 1.88 (br t, 3H, Ir-CH3), 3.36 (br d, 2JHH= 17 Hz, 2H, P-CH2Py), 4.23 (br d, 2JHH= 17 Hz, 2H,

P-CH2Py), 6.0 (br d, 1H, 3JHH = 8.00 Hz, Aryl-H), 6.70 (br t, 1H, 3JHH = 7.20 Hz, Aryl-H), 6.8 (br t, 3JHH

= 7.50 Hz, 1H, Aryl-H), 6.88 (br t, 3JHH = 7.00 Hz, 1H, Aryl-H), 7.14 (br t, 3JHH = 7.50 Hz, 1H, Aryl-

H), 7.34 (br t, 3JHH =8.00 Hz, 1H, Aryl-H), 7.60 (br signal, 1H, Aryl-H), 8.10 (br t, 3JHH = 7.00 Hz, 1H,

95

Py-H), 8.15 (br t, 3JHH = 7.00 Hz, 1H, Py-H), 8.85 (br d, 3JHH = 7.50 Hz, 2H, Py-H), 9.07 (br d, 3JHH =

7.50 Hz, 2H, Py-H), 13C{1H} (500 MHz, Tol d8): -3.5 (m, Ir-CH3), 31 (m, P-C(CH3)3), 35 (m, CH2P),

61.3(d, 1JPC= 62.8 Hz, P-CHPy) 95.5 (d, 4JPP= 8.8 Hz, Py-CH), 110 (m, Cipso), 111.6 (d, 3JPP= 24.0 Hz,

Py-CH), 121-131 (s, Aryl-C & Py-C), 158.8 (s, Py-CCH2P), 171 (br m, Py-CCH-P), 188 (m, Ir-CO) IR

υco(Ir-CO)= 2003 cm-1. The structure was confirmed by DEPT, C-H correlation experiment and 2D

COSY NMR.

Reaction of [Ir(tBuPNP)(C6H5)(CH3)][I-](63) with tBuOK.

Formation of [Ir(tBuPNP*)(C6H5)(CH3)](65).

To a THF solution of [Ir(tBuPNP)(C6H5)(CH3)][I-] (15 mg, 0.019 mmol) at 25 oC was added tBuOK

(2.00 mg, 0.018). The color changed from reddish to dark-red while stirring for 2 mins. The solution

was evaporated under vacuum and the resulting in a red solid was washed with pentane and filtered

through 0.2 micron Teflon filter. Than the pentane solution was evaporated under vacuum resulting in

a red-brown solid. 31P NMR revealed an A/M quartet as the major signal (more than 90%). 31P{1H}

NMR (C6D6): A/M quartet 20.5 (d, 2JPP= 328 Hz), 39.5 (d, 2JPP= 328 Hz). 1H NMR (500 MHz, CD2Cl2)

1.07-1.35 (m, 36H, P-C (CH3)3), 2.15 (dd, 3H, 3JPH = 5.99 Hz, 3JPH = 3.58 Hz, Ir-CH3), 3.0 (m, 2H, P-

CH2Py), 3.6 (dd, 1H, 2JPH = 4.29 Hz, 4JPH = 2.90 Hz, P-CHPy), 5.73 (br d, 1H, 3JHH = 6.37 Hz Py-H),

6.26-6.36 (m, 3H, Aryl-H & Py-H), 6.40-6.60 (m, 4H, Aryl-H & Py-H), 13C{1H} NMR (C6D6): -11.7

(m, Ir-CH3), 30 (m, P-C(CH3)3), 36 (m, CH2P), 62.5(d, 1JPC= 62.8 Hz, P-CHPy) 97.5 (d, 4JPP= 8.8 Hz,

Py-CH), 110 (m, Cipso), 111.6 (d, 3JPP= 24.0 Hz, Py-CH), 121-131 (s, Aryl-C & Py-C), 158.8 (s, Py-

CCH2P), 171 (br m, Py-CCH-P). The structure was confirmed by DEPT, C-H correlation experiment

and 2D COSY NMR.

Reaction of [Ir(tBuPNP)(C6H5) (36) with I2.

Formation of [Ir(CH2(CH3)2tBuPNPtBu) (I)][I](48').

Addition of 1 eq of I2 (6 mg, 0.023 mmol) to a benzene solution (2 mL) of 36 (15 mg, 0.023 mmol)

resulted in immediate color change. The solvent was evaporated and the resulting solid was washed

with ether. The orange yellow solid was then left under vacuum for one night allowing the isolation of

complex 48'. Complex 48' had a nearly identical NMR patter to that of 48.

Reaction of [Ir(tBuPNP)C6H5](36) with CO2.

Formation of [Ir(tBuPNP-COO-)(C6H5)(H)](66).

To a benzene solution of [Ir(tBuPNP)C6H5] 36 (15 mg, 0.023 mmol) at 80 oC was added CO2 small

excess. The color changed from grey-violet to yellow during 5 min. The solution was evaporated

resulting in a yellow-brown solid complex 67 in 80% yield (by NMR).

96

66: 31P{1H} NMR (C6D6): A/B quartet 55.70 (d, 2JPP= 354 Hz), 69.00 (d, 2JPP= 354 Hz). 1H NMR (250

MHz, C6D6) -23.90 ( dd , 1H, 2JPH = 18.25 Hz, 2JPH = 18.50 Hz), 1.00-1.51 (m, 36H, P-C (CH3)3), 2.55

(m, 1H, P-CH2Py), 3.0 (m, 1H, P-CH2Py), 5.10 (dd, 1H, 4JPH = 2.13 Hz , 2JPH = 6.07 Hz, P-CHCOO-

Py), 6.39 (d, 1H, 3JHH = 7.43 Hz, Aryl-H), 6.90-7.27 (m, 5H, Aryl-H & Py-H), 7.96 (br d, 1H, 3JHH =

7.1 Hz, Aryl-H), 8.45 (d, 1H, 3JHH = 7.5 Hz, Py-H). 13C{1H} NMR (C6D6): 26.7-28.6 (m, P-C(CH3)3),

34 (m, CH2P), 45(m, P-CHCOO-Py) 121.2 (m, Py-CH C3,5), 125.3- 135.4 (singlets, Aryl-C), 139.6

(s, Py-CH, C4), 141 (broad triplet, Cipso), 163.9 (s, Py-CC, C2,6) 180 (br m, P-CHCOO-Py), IR

υco(COO-)=1640 cm-1.

Reaction of [Ir(tBuPNP*)(COE)](35) with diphenylsilane.

Formation of [(tBu(C6H5)2HSiCH(PNP)Ir(H)(H)(SiH(C6H5)2)] (67).

To a benzene solution of [Ir(tBuPNP*)(COE)](35) (15 mg, 0.022 mmol) at 25 oC was added

diphenylsilane in small excess (50 μL, 0.25 mmol). The color changed from deep-red to yellow during

1 hr. The solution was evaporated resulting in a yellow-brown solid. The NMR consisted of several

signals including the A/B quartet, thus only charachteristic peaks will be presented. 31P{1H} NMR (C6D6): A/B quartet 61.20 (d, 2JPP= 343 Hz), 69.00 (d, 2JPP= 343 Hz). 1H NMR (250

MHz, C6D6) -8.50 (dd , 2H, 2JPH = 7.8 Hz, 2JPH = 8.3 Hz), 1.00-1.51 (m, P-C (CH3)3), 2.75-3.2 (m, P-

CH2Py), 5.5-6.1 (br s, Si-H), 6.90-7.4,(m, Aryl-H, Py-H).

Reaction of [Ir(tBuPNP*)(COE)](35) with CO2.

Formation of [Ir(tBuPNP-COO-)(COE)(H)](68)(68a).

To a toluene d8 solution of [Ir(tBuPNP*)(COE)](35) (15 mg, 0.022 mmol) at 25 oC was added CO2

small excess (0.67 mL, 0.03 mmol). The color changed from dark-red to orange during 10 min. The

solution was not evaporated and was characterized as is. 69 and 69a are most probably stereoisomers

thus, two A/B quartet were present in 31P NMR.

69+69a: 31P{1H} NMR (Tol d8): A/B quartet 52.1 (d, 2JPP= 368 Hz), 57.00 (d, 2JPP= 372 Hz), 62.5 (d,

2JPP= 372 Hz), 68.00 (d, 2JPP= 368 Hz). 1H NMR (250 MHz, C6D6) -24.80 (dd , 1H, 2JPH = 18.25 Hz, 2JPH =8.50 Hz, Ir-H), -24.95 (dd , 1H, 2JPH = 18.50 Hz, 2JPH =7.00 Hz, Ir-H), 1.00-1.51 (m, 36H, P-C

(CH3)3), 2.40 (m, 2H, CH=CHCH2), 2.55 (m, 1H, P-CH2Py), 2.80 (m, 2H, CH=CHCH2), 3.0 (m, 1H,

P-CH2Py), 3.2 (m, 1H, P-CH2Py),4.98 (dd, 1H, 4JPH = 1.13 Hz , 2JPH = 4.07 Hz, P-CHCOO-Py), 5.10

(dd, 1H, 4JPH = 1.15 Hz , 2JPH = 4.07 Hz, P-CHCOO-Py), 6.00 (t, 1H, 3JHH = 7.10 Hz, C=C-H), 6.40-

6.50 (m, 3H, 3JHH = 7.00 Hz, C=C-H, Py-H), 7.00-7.10 (m, 5H, Py-H). 13C{1H} NMR (Tol d8): 26.7-

28.6 (m, P-C(CH3)3), 34 (m, CH2P), 50(m, P-CHCOO-Py), 121.2 (m, Py-CH C3,5), 139.6 (s, Py-CH,

C4), 141 (broad triplet, Cipso), 163.9 (s, Py-CC, C2,6) 179 (br m, P-CHCOO-Py), IR υco(COO-)=1635

cm-1. The structure was confirmed by DEPT, C-H correlation experiment and 2D COSY NMR.

97

5 Appendix

121

Declaration of Independent Research and Collaboration

Most of the work in this thesis was done by me.

The following studies were done in collaboration:

a. Dr. Revital Cohen conducted the DFT calculations of the C-H activation process by the

(tBu2PNP)IrICOE complex.

b. Dr. Linda Shimon, Dr. Gregory Leitus and Dr. Haim Rosenberg were responsible for the X-ray

crystallographic determinations.

c. Yehoshua Ben-David synthesized the PNP ligands.

Sincerely,

Eyal Ben-Ari

122

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126

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Organomet. Chem. 1988, 356, 397 66 The protons were integrated with a time delay of 20 sec, calibrated to the pyridinic aromatic protons. 67 The de-aromatized pyridine protons of 3 give rise to three signals in the 1H NMR spectrum: one

characteristic signal at 5.67 ppm as a broad doublet and two multiplets at 6.45-6.85 ppm. The Ir-H

appears at -47 ppm. For detailed assignments see Supporting Information

68 Migration of the hydride ligand might be either intra- or inter-molecular. DFT calculations are being

performed on this system. 69 While CO coordination to Ir(I) followed by proton migration to the metal cannot be excluded at this

127

stage, we think that it is less likely because of the lower electron density at the Ir(CO) center. The

mechanism of this process is being studied. 70 Preliminary DFT calculations showed that the cis- isomer is more stable then the trans-isomer, and

should have been observed had it been formed. 71 (a) Rybtchinski, B.; Ben-David, Y.; Milstein, D., Organometallics 1997, 16, 3786. (b) Li, S. H.;

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S. J. Organometallics, 1991, 10, 467 73 When only 1 equivalent of H2 was used 50% of the starting complex was left unreacted the other

50% reacted to form the Iridium tris-hydride complex. 74 Dorta, R.; Shimon, W. J. L.; Rozenberg, H.; Milstein, D. Eur. J. Inorg. Chem. 2002, 1827 and

references their in. 75 (a) Werner, H.; Hofmann, L.; Feser, W.; Paul, W. J. Organomet. Chem. 1985, 281, 317. (b) Marder,

T. B.; Fultz, W. C.; Calabrese, J. C.; Harlow, L. R.; Milstein, D. Chem. Soc., Chem. Commun. 1987,

1543.76 Brook, A. M.;In Silicon In Organic,Organometallic and polymer Chemistry; McMaster University,

Hamilton, Ontario, Canada; John Wiley& Sons, Inc. 77 Arno, B.; In Carbon Dioxide Activation by Metal Complexes Weinheim; Basel; Cambridge; New

York, NY: VCH, 1988. 78 This complex was prepared in two steps; 1. saturating an ether solution of [Ir(COE)2Cl]2 with

ethylene which replaces the COE. 2. abstracting the chloride with AgPF6 and filtering off the AgCl.

this work was carried out under the supervision of ... · these findings, combined with dft...

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