SYNTHESIS AND PHYSICO-CHEMICAL STUDIES OF TRANSITION METAL COMPLEXES INVOLVING
N AND S DONOR MOIETIES
T H E S I S SUBMITTED FOR THE AWARD OF THE DEGREE OF
Bottor of pjntogopljp IN
CHEMISTRY
BY
MANZOOR AHMAD RATHER
DEPARTMENT OF CHEMISTRY ALIGARH MUSLIM UNIVERSITY
ALIGARH ( INDIA)
1998
aUr. Uanir. -At. ^J\nan
M.Sc.,Ph.D.(Alig.)
Fax No. Phone Talex
(0091) 0571-400466 0571(400515)
64-230-AMU-IN
DIVISION OF INORGANIC CHEMISTRY
DEPARTMENT OF CHEMISTRY ALIGARH MUSLIM UNIVERSITY ALIGARH -202002 (INDIA)
es^niviesiis
Certified that the work embodied in this thesis entitled
"Synthesis and Physico-Chemical Studies of Transition
Metal Complexes Involving N and S Donor Moieties" is the
result of original researches carried out by Mr. Manzoor
Ahmad Rather under my supervision and is suitable for
submission for the award of the Ph.D. degree of Aligarh
Muslim University, Aligarh.
( Dr .T.A. Khan )
DIVISION OF INORGANIC CHEMISTRY
DEPARTMENT OF CHEMISTRY ALIGARH MUSLIM UNIVERSITY ALIGARH-202002 (INDIA)
*? express my yrate^ullness cordially and relisAinaly to my
supervisor ^ ^ r . ^ f t h i f c^ \ l* o^h«»n {,or 6is invaluable assiduous
guidance. *t¥is persistent diligence and perseverance with prompt response
was courteous and sympathetic towards me throughout the tenure o£ this
research proaram.
'De^frite the impossibility a/ aivina credit to every one who has dee* o£
help. 0 would li6e to single tut certain people who have &eeu especially
instrumental, directly or indirectly in the completion o£ this work, /he
professional expertise and perspicuity 0^ fjtof. ^YY)> ^ b A f c l f - laced w uh
his keen interest in research, made it a remar&a^le and unfaraetaHe
achievement'.
*) aw privileged to than6 f3t of. *YY). yjlyns, Chairman.
'Department o£ Chemistry far providing necessary research facilities, *i¥is
unparalleled teaching at my post'-graduate level remained ad a. perennial
memory.
0 certainly appreciate the help and cooperation extended 6-y my
stimulating colleagues particularly 6y <&*. y$(*j\.f9* ~\?nvkey, ^fjed
^5. ^ASAo J^h«n ^$. v7slnm and (YQinnat ^hagufta in this endeavour. 1 hope none will fael sliahted &y the physical impossibility o£
listing every name. 1 have enjoyed a lot with my friends ^ A I D A I
1r lanzoor stywiad rCalh
M.Sc.,M.Phil.(Alig.)
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and otAei mem&ei& 0/ t6e family cv£a Aave cmttii&uted mue& tkiouaA t&ei*
innccmetadle tatii^iteA aver the yeatA including love and tufifroit morally a&
well at materially. f4yain at la&t &ut not lea&t 0 Have no <vaid& to exfueM
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MQctnxoor cA' f a t h e r
ABSTRACT
T his work deals with the synthesis and
structural studies of novel macrocyclic
complexes of transition metal ions (Mn", Co",
Ni", Cu"and Zn") and tin-transition metal
heterobimetal l ic complexes. Herein,
introductory chapter [1] embodies a succinct
account of the earlier work described in
literature and present objectives of undertaking
the studies in this area. The chapter [2] deals
AJbstract {'•• | l\
with the instruments used for characterizing the
various complexes. The chapter [3] describes
the basic experimental procedures, reagents used
to perform the synthesis of various metal
complexes and their results and discussion.
The first part [3.1] of the third chapter
deals with the synthesis and characterization of
a new series of heterobimetallic tin-transition
metal complexes: dichloro(l,2-diphenylethane-
1,2-dione bis l,2-diaminoethane)metal(II)-
dichlorotin(IV),[MCl;L'SnCl2]; dichloro(l,2-
diphenylethane-1.2-dione bis 1,3-diamino-
propane)metal(II) dichlorotin(IV), [MC12L2
SnCl2] [M = Mn11. Co", Ni", Cu" and Zn"];
dichloro(l,3-dimethylpropane-l,3-dione bis
1,2-diaminoethane)metal(II) dichlorotin(IV),
[MChL'SnCh] and dichloro(l,3-dimethyl
propane-l ,3-dione bis 1,3-diamino
p r o p a n e ) m e t a l ( I I ) - d i c h l o r o t i n ( I V ) ,
[MCl2L4SnCl2] [M= Mnn, Co11, Nin, Cu11 and
Zn11]. The reactions were carried out by treating
1,2-diaminoethane or 1,3-diaminopropane with
diketones (benzil or 2,4-pentanedione) in
presence of transition metal salts and tin(IV)
chloride in 2:1:1:1 molar ratio. The complexes
are stable to atmosphere at room temperature.
These compounds were characterized by using
a range of techniques including IR, 'H NMR,
EPR, electronic spectral studies, conductivity
and magnetic susceptibility measurements. The
elemental analyses results are acceptable with
the proposed stoichiometry of the complexes.
These adducts have very low solubility in
organic solvents, but are freely soluble in polar
solvents such as dimethylformamide,
dimethylsulphoxide and acetonitrile. All the
complexes gave molar conductance values
consistent with their non-electrolytic nature.
Q
The main feature of IR spectra is the
appearance of a band around 1600 cm'1 which
can be assigned to the azomethine linkage
v(C=N) and is consistent with coordinated imine
bonds. This information along with the absence
of bands due to carbonyl groups strongly support
that the condensation of primary amine with the
carbonyl group has taken place. The position
of another important v(N-H) band around
3170 cm'1 is in support of coordination through
amino nitrogen. The v(M-N) and v(Sn-N) bands
appeared around 450 cm"1 and 3 80 cm"1,
respectively. The complexes exhibit a broad
intense band in the 300-360 cm"1 region, which
may probably be associated with the v(Sn-Cl)
frequencies. The other vibrations appeared at
their expected positions. The 'H NMR spectra
of [ZnCl; (L'-L4)SnCl2] adducts appear to be
more complex and do not show any bands
assignable to primary amino protons. All the
compounds gave two multiplets between 6.08-
6.20 ppm and between 3.18-3.21 ppm which can
'' be assigned to the N-H protons (C-NH, 2H) and
the methylene (CH2-N, 8H) protons of amine
moiety, respectively. The 'H NMR spectra of
central methylene protons of 1,3-diamino-
propane and 2,4-pentanedione, phenyl ring
protons and imine methyls appear at their
respective positions. However, the broadness of
the 2.38 ppm band for the complex
[ZnCl2L4SnCl2] may be due to the overlapping
of middle methylene protons of 2,4-pen
tanedione and 1,3-diaminopropane. The EPR
spectra of copper(II) complexes exhibit g[ and
gx values in the range 2.23-2.28 and 2.10-2.14,
respectively, suggesting a distorted octahedral
structure around copper(II) ion. The spectral and
magnetic moment data support octahedral
Abstract
geometry for rest of the complexes.
The second part [3.2] of the chapter
presents the synthesis and characterization of
tetraoxotetraamide macrocyclic complexes:
dichloro/nitrato(6:7,14:15-dibenzo-5,9,12,16-
t e t r a o x o - l , 4 , 8 , 1 3 - t e t r a a z a c y c l o h e x a -
decane)metal(II), [ML5X2] [M = Mn11, Co", Ni",
Cu11 and Zn"; X = CI or N03] and dichloro/
nitrato(7:8,15:16-dibenzo-6,10,13,17 - tetraoxo
- 1,5,9,14-tetraazacycloheptadecane)metal(II),
[ML6X2] [M = Mn", Co", Ni", Cu" and Zn";
X = CI or NO?]. These complexes were derived
from anthranilic and succinic acids reacted with
1,2-diaminoethane or 1,3-diaminopropane in
presence of transition metal ions in 2:1:1:1 molar
ratio. The complexes are generally coloured and
polycrystalline in nature. They are obtained in
good yield and are stable in solid state. The low
molar conductance values suggest their non-
[[^Abstract ]jj: | l]
electrolytic nature.
The IR spectra of the complexes show a
medium intensity band in 3200-3240 cm'1 region j i ]
assigned to v(N-H) and appearance of a new | j
band in 400-440 cm"1 region ascribed to I
v(M-N) vibration. This plus the absence of bands
corresponding to primary amine and appearance
of amide bands provide strong evidence that the
cyclization has taken place. The ' H NMR spectra
of zinc(II) complexes show a broad signal in
the 8.41-8.46 ppm range assigned to amide
protons. This information along with the absence
of bands corresponding to the carboxylic or
primary amino protons support the
macrocyclization. The room temperature EPR
spectra ofthecopper(II) complexes gave g| and
gj. values in the 2.21-2.26 and 2.11-2.16 regions,
respectively, characteristic of octahedral
geometry having the unpaired electron in the
Abstract
dx2-y2 orbital. The spectral and magnetic
moment data are entirely consistent with six
coordination at the metal centres.
The third part [3.3] of the chapter reports
the synthesis and spectroscopic studies of
tetraiminetetraamide macrocyclic complexes:
dichloro/nitrato(6,7,14,15-tetraoxo-2,3,10,11 -
tetraphenyl-l,4,5,8,9,12,13,16-octaazacyclo-
hexadecane-1,3,9,1 l-tetraene)metal(II), [ML7
X2] [M = Mn", Co". Ni", Cu" and Zn"; X = CI
or NO?] and (6,7,14,15-tetraoxo-2,3,10,11-
tetraphenyl-1,4,5,8,9,12,13,16- octaazacyclo-
hexadecane-1,3.9,1 l-tet-raene)copper(II)
chloride/nitrate [CuL7] X2 [X = CI or N03]. The
complexes have been prepared by the
condensation reaction of 1,2-diphenylethane-
1,2-dione dihydrazone (DPEDDH) with
dimethyl or diethyloxalate followed by metal
templation in 2:2:1 molar ratio. Both starting
materials dimethyl and diethyl oxalate were used
with each metal leading to the identical products.
They are freely soluble in dimethylsulphoxide,
dimethylformamide and exhibit 1:1 metal to
ligand stoichiometry. The molar conductivities
indicate that copper(II) complexes are
electrolytic while others are non-electrolytic in
nature.
The most significant feature of IR
spectra of these complexes is the apprearance
of four characteristic amide bands in the 1680-
1715. 1510-1550, 1225-1255 and 635-670 cm"1
regions. The amide I, v(C=0) band is observed
in the region expected for metal-free amide
group ruling out the possibility of coordination
through amide oxygen. A single sharp secondary
amine band observed in the 3240-3275 cm'1
region, is similar to analogous metal-free
terraaza ligands which indicate that the amide
[j; Abstract , 10
nitrogens do not involve in coordination. The
complexes exhibit a strong intensity band in the
range of 1580-1595 cm"' assignable to the
coordinated v(C=N). There is observed increase
in the v(C=N) band intensity which may be due
to possible transformation of /ram-stucturure of
the free ligand (DPEDDH) into cis
configuration upon complexation. The 'H NMR
spectra of both the zinc(II) complexes showed
the appearance of a band at 8.42, 8.45 ppm
reasonably ascribed to amide (N-NH-C,4H)
protons. This information along with absence
of characteristic peaks corresponding to the
protons of hydrazone and oxalate moieties
further confirm that cyclization has indeed taken
place. The calculated g| and gx values of the
copper(Il) complexes appeared in the 2.31, 2.34
and 2.08, 2.09 regions, respectively, supporting
the contention that dx:-y: may be the ground
I
state of the unpaired electron and the complexes
are of ionic character. The spectral and magnetic
moment data suggest the square-planar geometry
around the copper(II) ions while other
complexes have octahedral geometry.
The fourth part [3.4] of the chapter
presents the synthesis and characterization of
bis(macrocyclic) complexes : dichloro/nitrato
[l,l'-phenylbis(3,6,9,12-tetrahydro-l,3,6,9,12-
pentaazacyclotridecane)metal(II), [M2L8X4]
[M = Mn", Co11, Nin, Cu" and Zn"; X = CI or
N03]; In these complexes two pentaazacyclo-
tetradecane subunits are linked by a biphenyl
group attached to an uncoordinated benzidine
nitrogen atom. The new series of
bis(macrocyclic) complexes have been
synthesized by the template reaction of metal
salt, benzidine, formaldehyde and triethylene-
tetraamine in 1:1:4:2 molar ratio. All complexes
[rAbstract'i,' | 121
are stable to atmosphere and are polycrystalline
in nature. Elemental analyses agree well with
the proposed structure. The molar conductance
values are supportive of non-electrolytic nature.
The most important feature of IR spectra
is that the complexes gave no bands assignable
to primary amino or carbonyl group stretching
modes. In all the complexes, a single sharp band
observed around 3210 cm"1 may be assigned to
v(N-H) of the coordinated secondary amino
group. These data strongly support the formation
of proposed macrocyclic moiety. The bands
around 1170 cm"1 assignable to v(C-N) vibration,
further confirm the suggested structure. The
*H NMR spectra of zinc(II) complexes show two
multiplets in 6.38, 6.41 ppm and 3.34, 3.36 ppm,
regions which correspond to the secondary
amino and methylene protons, respectively.
Another multiplet observed for both the
r
complexes in the 2.43, 2.46 and 7.23, 7.28 ppm
corresponds to the methylene protons of
triethylenetetraamine and aromatic ring
protons, respectively. More interestingly, no
band assignable to aldehydic or primary amino
protons is observed which strongly support the
concluded frame-work. The room temperature
EPR spectra of the copper(II) bis(macrocyclic)
complexes show g| andgi values at 2.25, 2.30
and 2.09, 2.14 respectively. In these
complexes, (gj < 2.3 and G < 4) is indicative of
the covalent nature and considerable exchange
interaction of the complexes. On the basis of
spectral and magnetic moment values an
octahedral geometry is proposed around the
metal ions.
The fifth part [3.5] of the chapter
describes synthesis and spectroscopic studies
of a new series of dithiadiaza macrocyclic
complexes :dichloro/nitrato( 1:2,7:8-dibenzo-
10,13-dioxo-3,6-dithia-9,14-diazacyclo-
tetradecane)metal(II), [ML9X2] [M = Co" or
Zn"; X = CI or N03]; (l:2,7:8-dibenzo-10,13-
d ioxo-3 ,6 -d i th ia -9 ,14-d iazacyc lo te t ra -
decane)metal(II) chloride/nitrate [ML9]X2 [M =
Nin or Cu"; X = CI or N03]; dichloro/nitrato
(1:2,7:8,11:12-tribenzo - 10,13 - dioxo - 3,6-
dithia-9,14-diazacyclotetradecane)metal(II),
[ML10X2] [M = Co" or Zn"; X = CI or N03] and
(1:2,7:8,11:12 - tribenzo - 10,13-dioxo-3,6-
dithia-9,14-diazacyclotetradecane)metal(II),
chloride/nitrate [ML,0]X2 [M = Ni" or Cu";
X = CI or NO:,]. These complexes were obtained
by the template condensation of metal salt,
1,2-ethane dithiol, o-bromoaniline and succinic
or phthalic acid in 1:1:2:1 molar ratio. The
complexes prepared have 1:1 metal to ligand
stoichiometry. The molar conductance values
Abstract [II [ 15
I I
indicate ionic nature of nickel(II) and copper(II)
complexes while cobalt(II) and zinc(II)
complexes exhibit their non-electrolytic nature.
The absence of IR bands characteristic
of thiol or hydroxyi groups and the appearance
of bands corresponding to an amide group
strongly suggest that the proposed ligand
frame-work is formed. In addition to this, bands
in the 395-420 and 330-370 cm"1 regions
assignable to v(M-N) and v(M-S) vibrations,
respectively, further confirm the proposed
structure. The other important vibrations
appeared at their respective positions. The
'H NMR spectra of zinc(II) complexes also show
the absence of carboxylic or thiol protons and
appearance of signals assignable to amide
protons which again confirm the proposed
frame-work. The EPR spectra of polycrystalline
copper(II) samples exhibited a strong single
i
Abstract 16
band with g( and gi values in the 2.32-2.37 and
2.09-2.12 ranges, respectively, indicating ionic
nature, which is well suited for electrolytic
nature of copper. The spectral and magnetic
moment values suggest that complexes derived
from nickel and copper have square-planar
geometry, while octahedral geometry is
proposed for cobalt and zinc complexes.
This project comes to an end with the
chapter [4] which concludes the work done.
LIST OF PUBLICATIONS
1) Spectroscopic studies of heterobimetallic adducts of Tin with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). T.A. Khan, M.A. Rather, S.P. Varkey, S.S. Hasan and M.Shakir, Main Gr. Met. Chem., 1996, 19(4), 225.
2) Tetraoxotetraamide macrocyclic complexes. T.A. Khan, M.A. Rather, N. Jahan, S.P. Varkey and M. Shakir, Transition Met. Chem., 1997 (in press).
3) Metal ion directed synthesis of tetraiminetetraamide macrocyclic complexes derived from 1,2-diphenylethane 1,2-dione dihydrazone. T.A. Khan and M.A. Rather, Supra. Mol. Chem., 1998 (Communicated).
4) Synthesis and characterisation of bis(macrocyclic) complexes based on the 13-membered pentaaza unit. T.A. Khan, M.A. Rather. N. Jahan, S.P. Varkey and M. Shakir, Synth. React. Inorg. Met.-Org. Chem., 1997, 27(6), 843.
5) Synthesis and spectroscopic studies of 14- membered dithiadiaza macrocyclic complexes of transition metal ions. T.A. Khan, M.A. Rather, A.K. Mohamed, K.S. Islam and M. Shakir, Coord. Chem., 1998 (Communicated).
CONTENTS
^CHAPTER FIRST GENERAL INTRODUCTION
1.1 References ^CHAPTER SECOND INSTRUMENTS USED
2.1 IR Spectroscopy 2.2 1H NMR Spectroscopy 2.3 EPR Spectroscopy 2.4 UV-V1S. Spectroscopy 2.5 Magnetic Susceptibility Measurements 2.6 Molar Conductance Measurements 2 7 Elemental Analyses
•* CHAPTER THIRD SYNTHESIS AND CHARACTERIZATION OF NEWLY CONDENSED COMPLEXES
PAGE NO.
1-37
38 52-57
53 54 54 55 55 56 57
58 -153
3.1 Synthesis and Spectoscopic Studies of Hetrobimetallic Complexes.
59
3.1.1 3.1.2 3.1.3 3.1.4
3.2
3.2.1 3.2.2 3.2.3 3.2.4
Introduction Materials and Methods Results and Discussion References
Synthesis and Characterization of Tetraxotetraamide Macrocyclic Complexes. Introduction Materials and Methods Results and Discussion References
59 60 62 78
80
80 81 83 97
PAGE NO.
3.3 Synthesis and Spectroscopic Studies 99 of Tetraiminetetraamide Macrocyclic Complexes.
3.3.1 Introduction 99 3.3.2 Materials and Methods 100 3.3.3 Results and Discussion 102 3.3.4 References 115
3.4 Synthesis and Characterization of 117 Bis(macrocyclic) Complexes.
117 119 119 133
3.5 Synthesis and Spectroscopic Studies 135 of Dithiadiaza Macrocyclic Complexes.
3.5.1 Introduction 135 3.5.2 Materials and Methods 136 3.5.3 Results and Discussion 138 3.5.4 References 151
3.4.1 3.4.2 3.4.3 3.4.4
Introduction Materials and Methods Results and Discussion References
»* CHAPTER FOURTH CONCLUSION 154-157
This chapter elucidates general introduction to the basic information related to the coordination complexes and the previous work done by eminent scholars.
Cfl
GENERAL INTRODUCTION
THVescr ib ing the full historical survey of coordination
J - ^ ^ chemistry which encompasses a great diversity of
substances and phenomena is beyond the limits of this chapter,
but it can be quoted that G.B.Kauffman1"5 has contributed to
this regard through his publications reviewing the pre-werner
theories and post-werner developments in a chronological order.
Although coordination chemistry comprises a large body of
current research in inorganic chemistry, it still presents
stimulating theoretical and practical challenges to an inorganic
chemist. The rapidly developing realm of bioinorganic chemistry is
Chapter 1 General Introduction CD
based on the presence of coordination compounds in living systems.
Many substances in vivo behave as multidentate ligands containing
numerous donor sites and act as metal carriers on complexation. For
example, many enzymes act as catalysts in the biological systems
which control the synthesis and degradation of biologically important
molecules and predominantly depend upon a metal ion for their
activity. Among the metals, molybdenum which achieved prominence
has attracted interest chiefly because of its role in biological
processes and also it shows a great variety of oxidation states and
coordination numbers. The newer types of compounds, mainly
coordination compounds, which have received vast study are
catalytically important (with their ease of oxidative addition and
reductive elimination), are the phthalocyanines, macrocycles, crown
ethers, metal-metal bonded complexes (metal clustures) and the
complexes in which hydrogen, ethylene, organic phosphines and
carbon monoxide behave as ligands. A highly comprehensive volume
has been devoted to the application of several coordination
compounds in various fields of practical importance to mankind.
The coordination complexes of a wide variety of Schiff-base
ligands have been extensively studied and reviewed8"14. The current
interest lies in the synthesis of multidentate ligands because of their
Chapter 1 General Introduction
ability to form mono and bis-species, yielding complexes with
different structural features. The metal derivatives of these ligands
have drawn substantial attention from the researchers for their
biological activities15"22. The molecules of life such as amino acids
have been exploited for the synthesis of Schiff-base ligands and their
23-32 transition metal complexes
The idea that two metal atoms in close proximity could react in
a cooperative manner with substrate molecules gave rise to binuclear
system . A major role in the building of binuclear complexes has
been played by tertiary diphosphines, bis(diphenylphosphino)
methane (dppm) being particulary efficient for this purpose .
Substitution of one of the donor atoms in the dppm skeleton for a
softer (As) or harder (N) centre has been introduced to create
heterobinuclear complexes of the platinum group metals3""39. Such
ligand systems studied by Balch have led to the synthesis of Pt-Rh
complexes having two bridging ligands A large number of
transition metal-gold multimetallic complexes have been prepared
containing transition metals V. Cr. W. Mn, Re, Fe, Ru. Os. Co, Rh,
Ir. Pt and Ag41"4\ On the other hand, the synthesis and
characterization of Pd-Au cluster compound has been reported
because Pd is a catalytically important metal and Au-Pd heterogenous
Chapter 1 General Introduction i CE
catalysts are known and commercially used for oxidation catalysis .
Copper(II) complexes with various ligands derived from oxalates,
oxamidates, oxamates [CuL] are known to act as paramagnetic
ligands towards other metal ions46 . In particular it has been found
that strong antiferromagnetic coupling is operative when CuL is
bound to metal ions (Cu"\ Ni2~ or Mn2T) in a pseudo-octahedral
(square-planar in case of copper) environment47"50. Kahn and co
workers 5 ' have found that CuL can form ferromagnetic chains with
XV and Mn" and that these chains can order magnetically at
sufficiently low temperature. F a b r e t t i " has used CuL as a
paramagnetic ligand which forms with nickel(II) a trinuclear
complex. The peculiarity of this compound is that the central
octahedrally coordinated nickel(II) ion has two water molecules with
c/A-configuration. In the recent past the crystal and molecular
structure of a very interesting binuclear compound, bis [|A-3, 5-bis(21
-pyridyl) pyrazolate- N1 X :X : X"]-bis [dimethanol nickel(II)]
dichloro -dihydrate has been reported54. Two methanol molecules
have been shown to be bonded to each nickel(II) rendering an
octahedral environment.
The chemistry of macrocyclic ligands proves to be a
challenging research area, as these molecules display unique and
Chapter 1 General Introduction |
exciting chemistries due to their function as receptors for substrates
of widely differing physical and chemical properties and upon
complexation can drastically alter these properties. The numerous
work done by countless researchers with thousands of papers,
hundreds of reviews and numerous patents about the chemistry of
macrocyclic complexes can not be confined to few pages. The field
has undergone spectacular growth after the early 1960s due to the
pioneering independent contributions of Curtis55 and Busch56.
The synthesis and applications of macrocyclic moieties
involving aza(N). oxa(O), phospha(P) and sulfa(S) ligating atoms
have been a subject of considerable interest in the recent years. The
designing of new macrocyclic complexes is a current domain of
research due to their use as models for protein metal binding sites of
metalloproteins in biological system"7"60, as therapeutic reagents in
chelate therapy61 '6", as cyclic antibiotics that owe their antibiotic
actions to specific metal complexation63 '65, as models to study the
magnetic exchange phenomena6 6 6 7 and in catalysis6869 . Besides
these, there are a number of important biological processes such as
photosynthesis and dioxygen transport70 in which macrocyclic
complexes are involved.
Chapter 1 General Introduction B
The first macrocyclic compound prepared from a diacid was
dimeric ethylene succinate [1] reported by Vorlander in
V—v° / 6 CK
Fig. 1
1894, subsequently, very little work was done with macrocyclic
diesters untill 1930's when Carothers and co-workers commenced
a study of polyesters including the macrocyclic monomeric and
dimeric carbonates, oxalates etc. The main interest in macrocyclic
diester compounds involved their use in preparation of perfumes
First documented macrocycle possesing a (Pynole) [2]
subheterocyclic ring was synthesized in 1886 by Baeyer 4 via the
condensation of pyrrole and acetone in the presence of mineral acid.
Macrocycles can be synthesized either by template method or
via non-template synthetic routes. The former route is prefered
because of the conformational requirements of the reacting species in
the reaction medium. The metal ion plays an important role in
Chapter 1 General Introduction
H,Cv o •CH,
N 0 H3C
N
CH,
Fig. 2
directing the steric course of the reaction and this effect has been
termed as "metal template effect"75. The exciting aspect of this effect
is that in majority of cases the molecules meet the design criteria
very well. The metal ion may also direct the condensation
preferentially to cyclic rather than polymeric products and there by
increasing the yield of product. The preparation of the free
macrocycle has certain advantages in many cases. Firstly purification
of the organic product may be more readily accomplished than
purification of its complexes and secondly, the characterization by
physical techniques will be more easy. However, the synthesis of a
macrocycle in the free form results in a low yield of the desired
product with side reactions, such as polymerization as predominating
effect. In order to overcome this problem, the ring closure step in the
synthesis may be carried out under conditions of high dilution76.
Chapter 1 General Introduction ] CXI
The multidentate macrocycles give rise to unique, rather cryptic
77 7ft
geometries ' These macrocyclic ligands are cyclic molecules
consisting of an organic framework interspersed with heteroatoms
which are capable of interacting with a variety of species. It is now
well established that macrocyclic molecules containing the biting
centres as [N4], [N6], [N8], [N 40 2] , [N4S2],and [N2S2] display unique
and exciting chemistry in that they can stabilize unusual higher
oxidation states of metal ions. The chemistry of metal complexes
with cyclam or related tetraaza macrocyclic ligands has been
extensively developed . These macrocyclic complexes have proven
to be a topic of continual and growing interest to coordination
chemists. Curt is has demonstrated the template potential of metal
ions in the formation of the isomeric tetraazamacrocyclic complexes
[3 and 4] by treating [Ni(en)3](C104)2 (Scheme 1) with acetone80.
The first example of a deliberate synthesis (Scheme 2) of a
macrocycle [5] using this procedure was described by Thompson and
Busch5 . Much of the early work featured the use of transition
metal ions in the template synthesis of quadridentate macrocycles:the
directional influence of orthogonal d-orbitals was regarded as
instrumental in guiding the synthetic pathway81 . This technique has
\3
H2 H 2
>U N \ /
H2 H 2
VrO
o re ft
O § • ' o
5' 3
Scheme 1. Illustration of the formation of macrocyclic complexes by the metal template method by Curtis.
H 2 N N S
w R^O
R. /"A N .S
\ / Ni
w r^
Br
Br
r\
Scheme 2. The first example of a delibrate synthesis of macrocycle by template method by Thompson and Busch.
Chapter 1 General Introduction an been extended in the last decade by using organotransition metal
derivatives to generate tridentate cyclononane complexes . The
synthesis of macrocyclic complexes by the metal template method
was extended by the use of .v,/?-block cations as template devices to
synthesize penta and hexadentate Schiff-base macrocycles " and a
range of tetraimine Schiff-base macrocyies by the Sheffield
j r» l r . ^ 0 . 9 1 ,
and Belfast research groups.
The template potential of a metal ion in the formation of a
macrocycle depends on the preference of the cations for stereo -
chemistries in which the bonding ^-orbitals are in orthogonal
arrangements. This is exemplified by the observation that neither
CuH nor Ni" act as template for the pentadentate "'1 + 1" macrocycles
[6-8] derived by the Schiff-base condensation of 2.6-
diacetylpyridine with triethyienetetraamine. N,N -bis(3-amino-
propyl) ethylenedia mine or N. N -bis(2-aminoethyl)-1.3-propane-
diamine.respectively. However. M g ' \ Mn" . Fe~\ Fe '". Co" . Zn" .
Cd2 and Hg2 serve as effective templates leading to the
formation of /-coordinate complexes of [6 and 7] and pentagonal
bipyramidal geometries for Mg "". Mn'". Fe '" , Fe^ . Zn2 . Cd" and
6-coordinate pentagonal pyramidal geometries for Co2 . Cd2 and
Hg" ** . The metal ion and the anion are important to the template
Chapter 1 General Introduction 13
Fig. 6 Fig. 7
Fig. 8
process because the balance between the size of the cation and
anion will determine the degree of dissociation of the metal salt in
the reaction medium47.
Chapter General Introduction 14
The formation of "1+1" macrocycle via intramolecular
mechanism or "2+2" macrocycle via the bimolecular mechanism
depends on one or more factors during the synthesis of Schiff-
base macrocycles. They are
1) The insufficient chain length to span the two carbonyl groups
in the diamine will block the formation98 of "1 + 1" macrocycle.
2) A "2+2" condensation may occur" if the template ion is
large with respect to the cavity size of the "1-^1" ring.
3) The electronic nature of the metal ion and the requirement of
a preffered geometry of the complex.
4) The conformation of the "1 + 1" acyclic chelate.
In the synthetic pathway of macrocycles the size of
cation used as the template has proved of much importance. The
compatibility between the radius of the templating cation and "hole"
of the macrocycle contributes to the effectiveness of the synthetic
pathway and to the geometry of the resulting complex. For example,
cations of radii less than - 0.80A0 do not seem to generate complexes
of [8]. Fenton and co-workers 8 S . 8 8 . 9 1 . 0 9 . J 0 0 d e m o n s t r a t e d c a t i o n .
cavity "best fit" in the formation of Schiff-base macrocycles by
synthesizing oxaazamacrocycles using alkaline earth cations as
templating devices. The smaller metal ion favours the formation of
Chapter 1 General Introduction QI
"1 + 1" [9] while the large metal ion favours the formation (Scheme 3)
of "2+2" macrocycle [10]. One of the alkaline earth cations, for
example, only magnesium generates the pentadentate "1 + 1"
macrocycle [9] but it is ineffective in generating the hexadentate
"1 + 1" macrocycle [11] which is readily synthesized in the presence
of large cations such as Ca2 , S r 2 \ Ba2 and pb2+. The preference
for the formation of "1 + 1"" or "2+2" Schiff-base macrocycle in the
metal template condensation depends on the cation radius. There is
an alternate method for the template synthesis of Schiff-base
macrocycle in which the metal free ligands can be synthesized by an
acid-catalysed condensation. Sessler et al.101 have produced pyrrole
containing macrocycles by the acid-catalysed Schiff-base
condensation of diformyltripyrrane with 1,2-diaminobenzene or 1.4-
diaminobutane. When the reaction was carried out in presence of
basic metal salts such as BaCO^ as a potential template, no
macrocycle could be isolated However, final product was obtained in
high yield when the Schiff-base condensation is effected in the
presence of stoichiometric quantities of larger cations such as CIO2"
and Pb~\ provided that an acid catalyst is also employed. The method
of synthesizing novel macrocycles by the acid-catalysed Schiff-base
condensation led to suggest a general "anion template effect".
Chapter General Introduction 16
+ H N 0 0 0 NH 2
S r 2 ; Pb2 '
r\ r-\ / H,N 0 i.' NH2
x—o /o —
Fig. 9
Fig. 11
N N ^
X
Fig. 10
Scheme 3
Chapter 1 General Introduction 17
The Schiff-base condensation of the appropriate diamine and
dicarbonyl precursors in presence of an alkaline earth metal ion,
commonly resulted in the formation of macrocyclic complexes in
good yield87. Some reactions demonstrate the facility and
reversibility of amine exchange (transamination) and its importance
in the metal ion template synthesis of macrocyclic Schiff-base
ligands. Thus it has been observed that excess of free diamine or free
metal ion suppress the formation of macrocycle. The sequence of
reactions involving ring closure by transamination with a concomitant
ring contraction and reduction in ligand denticity and subsequent ring
expansion in the presence of larger metal ions is illustrated in
Scheme 4. Thus it has been described102 that when the metal ion is
too small for the macrocyclic cavity, ring contraction takes place by
transamination with a concomitant reduction in ligand denticity and
ring size. The complex of the ring contracted macrocycle undergoes
ring expansion in the presence of larger metal ions.
Lindoy and co-workers have developed design strategies for
new macrocyclic ligand systems which are able to recognize
particular transition and post-transition metal ions, they have
prepared ' " ? and studied the discrimination of metal ions by
Chapter General Introduction 18
+ r~\"/-\ -#v H2N N NH2 Ca, Ba
C * "D ^ N H
NH HN
2 H2N 3
Co2; Bo2* l s ^ J 2 Cu
2*
Scheme 4
Chapter General Introduction 19
r^ w W
Fig. 12 Fig. 13
ligand and by following the occurence of "structural dislocation"
along a series of closely related [12 and 13] mixed donor ligand
svstem 106-110
Macrocycles containig nitrogen donor atoms have been used as
models to explain metal ion-maci -cycle reactions in biological
systems. Among the poiyaza macrocycles, the tetraaza groups have
been the most extensively studied. Pentaaza and higher
polya7amacrocycles have begun to appear more frequently,
particularly in view of the potential of the larger macrocycles to bind
more than one matal ion. Margerum and co-workers 111-113 have
reported extensive investigations on the interaction of CM" and Ni"
with the macrocycles containing nitrogen donor atoms. The chemistry
of synthetic macrocyclic polyamines and macrocyclic
dioxopolyamines have been drawing much interest114""6. These
macrocycles form much more stable and selective complexes with
Chapter General Introduction W
various transition-metal ions than to open chain analogues having the
same donor arrangement. The metal complexes of the /-/-membered
cyclic tetraamine 1,4,8.1 1-tetraazacylotetradecane [14] represent
1 17 reference svstems in the coordination chemistry of
I I azamacrocyles. The synthesis of ligands [15 - 17] led to the
N N
H? NH
Fig. 14 Fig. 15
^ N H HN
Fig. 17 Fig. 16 J
U" study of their complexes. Studies on their complexes proved that
above [15 - 17] form stable complexes with transition-metal ions ' 1 9
and the Cu" complex of the /-/-membered [16] is the most stable among the three complexes . Majority of nitrogen-donor
macrocycles that have been studied are quadridentate e.g. ligands [14
and 18]. To fully encircle a first row transition-metal ion in a
Chapter 1 General Introduction 21
macrocylic ring size of between 13 and 16 members are required
provided that the nitrogen donors are spaced such that, five, six- or
seven-membered chelate
coordination7 5 1 2 0 1 2 1 .
on rings are produced
A number of larger ring macrocycles
ft r\A/-\ W v w
Fig. 18 Fig. 19
containing more than four donor atoms have also been prepared and
one example of such a large ring ligand12" incorporating more than
one metal ion is shown in fig. 19. Roger Guiiard " and his
associates synthesized new cyclam-based macrobicyclic ligands.
Very recently acid catalyzed rearrangements between J,-/-dihydro-
2H-1, 5-benzooxazocine and benzothiazocine led to the formation of
/6-membered, 2-/-membered. 32-membered macrocyclic ligands 124
Chapter 1 General Introduction QI
Great efforts have been made in the incorporation of
functionalized pendant groups into a saturated macrocyclic structure
to modify conformational and redox properties of its metal
complexes. Recently E. Kimura and co-workers have exported a few
examples of the macrocycle dioxotetraamines bearing functionalized
pendant g roups 1 2 \ Hay and co-workers126 studied tetraaza system
which has pendant primary amine function able to coordinate the
metal centre. Bush and co-workers studied " a macrocycle with a
pendant pyridyl function which is sterically restricted in its binding
to the metal centres. Macrocyclic ligands with pendant donor groups
have received much attention in last few years ' " and in some
cases129 pendant donors have been found to stabilize the trivalent
oxidation state of nickel and destabilize the trivalent oxidation state
of copper.
The amide macrocyclic ligands are of great interest because
their metal complexes can function as porphyrin analogues in
catalyzing organic oxidation reactions1"1'1"". The coordination
chemistry of polyamide macrocycles is of particular interest in veiw
of two potential donor atoms i.e., amide nitogen and oxygen.
However in most of the polyamide macrocytic complexes, amide
nitrogen is engaged in coordination and not the oxygen133. The
Chapter General Introduction 23
formation of an amide is normally carried out after conversion of the
carboxyl component to a more reactive acyl derivative which can
react with the amino component under mild conditions. A number of
macrocyclic tetraamides have been described in the literature. Rybka
and Margerum134 have discussed the chemistry of ligand [20],
which was prepared by the conventional methods employed in
rf . H I I H
0 lCH2>m 0
H i u
/ \
Fig. 20 Fig. 21
peptide synthesis. An American group13" has described a general
method for the synthesis of macrocyclic tetraamide ligands [21] by
aminolysis of the thiazolidine-2-thione amides of dicarboxylic acids
with diamines. Macrocylic tetraamides can be prepared in high yield
bv this route.
Shakir et al. is currently engaged in the synthesis of amide
. They have reported a wide variety of macrocyclic complexes'36"140
Chapter General Introduction 24
/ M \ / M \ _
JIT N N X NN
O - ^ X v ^
H H rN N
CI H H N Nv
H H
0
M
/ | \ N CI
N N ' H H
^ 0
HN-' ^ / M C
N H\_
- X - .
iX
N
M:
N Ilk
Fig 22-26
Chapter 1 General Introduction 25
tetraaza, hexaaza and polyaza macrocyclic [22-26] complexes
bearing amide groups. Most of them were prepared via the template
condensation reaction of (2+2) dicarboxylic acid with di or tri amines
and by self condensation of o-aminobenzoic acid. Very
recently 1 4 1 . 1 4 2 we were successful in synthesizing polyaza-
macrocyclic [27 and 28] complexes incorporated with peptide bonds.
Me
H II CI |„ N N | N N
Fig. 27 Fig. 28
Binucleating macrocyles were first obtained by Pilkington and
Robson *' by 2:2 condensation of 2.6-diformyl-4-methyl phenol and
1.3-diaminopropane The design and synthesis of binuclear
ma crocyclic transition metal complexes remains an important
Chapter 1 General Introduction 1 Q3
objective as potential catalysts due to influence of the two metal
centres on the electronic, magnetic and electrochemical properties of
such closely spaced paramagnetic centres. Binueleating ligands with
dissimilar coordination sites are of particular interest because such
macrocyclic complexes are thermodynamically stabilized and
kinetically retarded with regard to metal dissociation and metal
substitution relative to metal complexes of acyclic ligand.
Bis(macrocyclic) complexes incorporating two metal ions are of
great interest as they act as multi-electron redox agents or catalysts
and can be regarded as models for polynuclear metalloenzymes.
Furthermore they can exhibit interesting physical properties due to
the metal-metal interactions. Consequently, there has been a great
deal of work aimed at synthesizing biomimetic multinuclear models
which may provide insight into the actual structure of the
metalloenzyme or the mechanism of the catalysis. Recently
bis(macrocyclic) diiron and dinickel144 compounds have been
synthesized in which the diiron complex contains a conjugated bridge
between two metalin macrocyles. M.P. suh and co-workers14"
synthesized bis(macrocyclic) Ni(II) and Ni(l) complexes [29] by
template condensation reaction of formaldehyde and primary-
Chapter General Introduction 27
r\» \ N H
N — R — N JO
Fig. 29
diamines. Fenton has reviewed146 this class of compounds
emphasizing their relevances to bioinorganic model system. Some
polyaza macrocyclic complexes have been modified and the reactions
of nickel(II) and iron(II) complexes of 1.4,8,11-
tetraazacyclotetradecane [14] with H 2 0 2 and 0 2 respectively,
H / \ •N N
•N N = H \ /
H N N
N N H
were reported 1 4 7 . 1 4 8
Fig. 30
to produce correspoding complexes of
unsaturated [30] bis(macrocyclic) ligands. Shakir and co-
149 workers synthesized a new series of bis(macrocyclic)
complexes [31] from the template reaction of primary diamines.
Chapter 1 General Introduction 28
vYvH H O M S s N / i N H
Fig. 31
formaldehyde and benzidine followed by the addition of diketones or
phthalaldehyde.
P. Comba and co-workers have also synthesized130 some bis-
(macrocyclic) octaamine dicopper(II) complexes in which they have
found that these dicopper(II) complexes do not exihibit any coupling
in their EPR spectra irrespective of the size of the bridge which is in
contrast to observation with other (CH2):-linked bis(macrocyclic)
dicopper(II) complexes1"1 1?2.
Metal-ion recognition is a fundamental property of many
processes in nature, but the factors influencing such recognition are
often not well understood, especially when substrates incorporating
mixed donor sets are present. The aza-crowns have complexation
Chapter I General Introduction ] Q3
properties that are intermediate between those of all oxygen crowns
and of all nitrogen cyclams. Recent153 studies have proved that
macrocylic thioethers readily bind to transition metal ions to form
stable complexes. Bernardo and co-workers'54 have made a study of
the influence of saturated nitrogen and sulfur donor atoms on the
properties of copper(II/I) macrocyclic polyamino polythiaether ligand
complexes. Many macrocyclic complexes in which the furanyl moiety
is part of the macrocyclic frame-work have been reponed
ear l ier l 5 V l ' 6 . Busch and co-workers7 5 1 2 0 1 5 7 have synthesized several
sulfur-nitrogen containing macrocydes by in situ methods in
presence of metal ions, yielding the metal complex directly.
Metal complexes mainly of nickel(II) and cobalt(II) containing
'wo sulfur and two nitrogen1"8"160, four sulphur and four nitrogen1 ',
two sulfur, four nitrogen and one sulfur and four nitrogen
donors (,~ have been synthesized and in some cases the metal-free
ligand has also been obtained. The complexes with four sulfur and
two nitrogen donors have four sulfur atoms in an equitorial plane and
two nitrogen atoms are at trans positions. However, in two sulfur and
four nitrogen donor atom complexes, the metal is located in a cavity
bound by six donor atoms octahedrally. Funkemeier and
Chapter General Introduction 30
Fig. 32
163 co-workers recently. reported the synthesis of /-/-membered
trans N2S2 dibenzo macrocycle [32]. Very recently, J. Scowen with
other researchers164 reported metal-ion directed synthesis of
novel sufur-based [33 and 34] macrocycles. Reaction forming acid-
stable dittiiadiaza macrocycles proceeded in reasonable yield with
1 *
\
-Xi •W
oc * s
s
N
Fig. 33 Fig. 34
Chapter 1 General Introduction ] QE
carbon acid, even when stoichiometric amount of the carbon was
employed. Evidently, the condensation reaction of forming 13 to 16-
membered macrocycles for N4 donor molecules165"166 transfers readily
to mixed S2N2 donor analogues, with the presence of a pair of cis
disposed primary amine groups being the primary requirment for
condensation.
In recent years1 6 7 1 6 8 considerable attention has been devoted
for the synthesis and characterization of mixed nitrogen, oxygen and
sulfur donor atom macrocyles. L.F.Lindoy and associates
synthesized novel macrocyclic ring [35] incorporating mixed
NH 1
Fig. 35
(O4N2. O2S2N2 and N2S4) donor set and its complexation behaviour
towards copper(II), silver(I) and Lead(II) was also studied. The
behaviour towards silver(I) was of particular interest since inherent
in the design of these systems are structural features which appeared
•9 i>
Chapter 1 General Introduction ] EH
likely to enhance their relative affinity for this ion over other ions of
interest.
The synthesis of novel polythioether macrocyclic ligands and
their studies of coordinating abilities towards transition metal ions
have come into great prominence in last years. In spite of the fact
that the thioethers were formerly considered poor donors to the
transition metal ions1 °. Extensive work has been reported171, mainly
because of their possible use as models for metalloproteins. L.
1 7 ^
Escriche and his associates ' reported the synthesis of a large
macrocycle incorporating six sulfur atoms into the macrocyclic
frame-work and its structure was determined on the basis of x-ray
crystallography. Therefore, a great quantity of chemical and
structural information regarding their complexes may now be found
in the literature.
The observation that transition metal Schiff-base complex
[ML](L = quadridentate Schiff-base) can function as a neutral donor
ligand has led to several investigations of their reaction with tin
Lewis acids and to the isolation of their adducts174 175. In recent years
considerable spectroscopic information has been obtained on the
transition metal-tin complexes176. This not only has provided
additional insight as to the structures of these complexes and the
Chapter General Introduction 33
nature of transition metal-tin bonding, but also has given detailed
information as to the nature and relative amounts of the various
species present in solution. There is emerging greater use of these
species in the catalysis of organic transformations, such as def ine
hydrogenation and isomerization, reductions under water gas shift
conditions, hydroformylations coupling reaction among others.
The coordination chemistry of stannylenes, R^Sn explains a
considerable amount concerning tin-transition metal complexes.
These compounds use two of their p electrons in covalent bonding
and their other two electrons constitute a lone pair that can be used
to form an adduct with a lewis acid. There are also low-lying empty
p and d orbitals, which when used in the hybridization of the orbitals
of tin. create empty orbitals suitable for complex formation. There
sp
I
/ ••Sn— :Sn
sp
i i
:Sn \
sp
i l l
:Sn "Sn
s p 3 d
IV
sp J d '
Fig. 36
are several hybridization geometries177 available [36] for stannylenes.
Chapter 1 General Introduction 1 Ql
The first and fifth structures are uncommon for tin in transition metal
chemistry1 7 7 1 7 8 , while the second, third and fourth are most
important. Stannylenes form stable adducts with hard Lewis bases
such as amines and ethers, soft Lewis bases like halides, hard Lewis
acids1 7 y l 8° like the boron halides and soft Lewis acids like transition
. i 1 7 7 . 1 8 !
metals
The ability of metal salicylaldimine complexes to act as
effective bidentate donor ligands to tin(IV) halides, organo-tin(IV)
halides, pseudohalides and tin(II) halides are well
documented174 1 8 2 1 8 \ B.Clarke and co-workers recently reported184
the crystallographic and tin-119 mossbauer spectroscopic studies of
heterobimetallic complexes of 3-methoxysalicylaldimine ligands.
Many research groups have shown that tin(IV) Lewis acids form 1:1 i n i | i r I R S
adducts with transition metal Schiff-base complexes " and the 1 S f\
structures of many such adducts have been reported . One of the
specific interest in complexes of this type relates to the manner in
which the dioxygen-carrying properties of cobalt salicylaldimine
complexes are altered when they assume the role of donor Uganda,
particularly to t i n 1 8 . Siddiqi and his associates
synthesized188 heterobi- metallic complexes of the type
[Cu(TETA)Cl2SnCl2] and [Cu(TETA)Cl2SnPh2] by treating
General Introduction
EtOH
H
r K / ^ H i
Cu
/ L MH,
\r
H + 2HCI \
"V
/ L
Cu Sn
N -A.
VS
C6»5
CI
Scheme 5
Chapter General Introduction f36l
[Cu(TETA)Cl2] (TETA = triethylenetetraamine) with SnCl4 (Scheme
5). Interestingly the interaction of [Cu(TETA)Cl2 SnCl2] with an
exces of KBH4 in THF leads to the formation189 [37] of
[Cu(TETA)(BH4)2Sn(BH4]2. The complexes [38] of
CI
— N
•N
\ I
l\
N
Cu
N
J H
CI
s
Fig. 37 Fig. 38
[Cu(TETA)Cl2 M(TMDTC)2] (M = Si, Ge, Sn, Ti and Zr; TMDTC =
tetramethylene-dithiocarbamate) also appeared in the literature
Metal complexes of tetradentate Schiff-bases can act as bidentate
ligands coordinating to both transition and alkaline earth metal
atoms . I t has been shown that organo-tin(IV)chlorides form
molecular complexes with tetradentate Schiff-bases as well as with
their metal complexes. The bahaviour of bidentate ligand, N, N'-
Chapter General Introduction 37
ethylene bis(Salicylideneiminato) nickel(ll) towards organo-
tin(lV)chlorides resulted in the formation of heterobimetallic adduct
and its structure has been studied through crytallographic studies 192
Cunningham and co-workers have made many spectroscopic
studies187 especially mossbauer investigation of the transition metal
Schiff-base complexes as ligands in tin chemistry. The interesting
chemical and stuctural consequence of replacing one chloride by a
1 8 S
hydroxide or alkoxide ion have also been attempted ".
The chemisty of transition metal-tin and macrocyclic complexes
is an expanding field of research and thus thought worthwhile to
carry out some synthesis of novel heterobimetallic and marocyclic
moieties which may add up to this vast area of knowledge.
Chapter 1 | [ References j | 38
1.1 REFERENCES
1. G.B. Kauffman. "Alfred Werner : Founder of Coordination Chemistry", Springer-Verlag, Berlin, 1966.
2. G.B. Kauffman, "Classics in Coordination Chemistry, Part I, The Selected Papers of Alfred Werner" New York, 1968.
3. G.B. Kauffman."Classics in Coordination Chemistry,?art I I , Selected Papers (1798-1899)," Dover, New York, 1976.
4. G.B. Kauffman. "Classics in Coordination Chemistry, Part I I I , Twentieth Century Papers (1904-1935)," Dover, New York, 1978.
5. G.B. Kauffman. "Inorganic Coordination Compounds", Heyden, London. 1981.
6. E.I. Stiefel, Prog. Inorg. Chem., 1977, 22, 1.
7. G. Wilkinson. R.D. Gillard and J.A. Mccleverty. "Comprehensive Coordination Chemistry", Vol. 6, Pergamon Press. Oxford. 1987.
8. S. Yamada, Coord. Chem. Rev., 1965. 1, 415.
9. L. Sacconi. Coord. Chem. Rev., 1966, 1, 126.
10. R.H. Holm, G.W. Everett Jr. and A. Chakravorty, Prog. Inorg. Chem., 1966, 7. 83.
11. R.H. Holm and M. J. O'Conner, Prog. Inorg. Chem., 1971, 14. 241.
12. S. Yadama and A. Takeuchi, Coord. Chem. Rev., 1982, 43, 187.
13. F. Cariati, M. L. Ganadu, A. Zoroddu, R. Marsani and R. Quidacciola, Inorg. Chem., 1985, 24, 4030.
Chapter 1 References 39
14. A. Syamal and M.R. Maurya , Coord. Chem. Rev., 1989, 95, 183.
15. B. Nanda, S. Padmanavum, B. Tripathi and A. S. Mitra, J. Ind. Chem. Soc, 1975, 52. 533 .
16. L.S. Goodman and A. Gi lman, "The Pharmocological Basis of Therapeutics" 4th Edn. Mcmil lan and Co. , London, 1970.
17. The Merck. Index. "An Encyclopedia of Chemicals, Drugs and Biologicals, " 10th Edn. Merck and Co. , Inc. Rahway, N. J., U.S .A. , 1983.
18. R.H. Wiley and P. Wiley, "Heterocyclic Compounds. Pyrazolones and Pyrazohdines and Derivaties, " Interscience. New York, 1964.
19. Kiran, R.V. Singh and J .P. Tandon, Synth. React. Inorg. Met.-Org. Chem.. 1986, 16, 1341.
20. R.J. Hill and C E P . Richard, J. Inorg. Nucl. Chem., 1978, 40. 793.
2 1 . L. Donet t i , S. Sitron. F. Modalsso , G. Bandoli and G. Paolocci . J. Inorg. Nucl. Chem., 1980, 42, 1060.
22. P. Jain and K..K. Chaturvedi , J. Inorg. Nucl. Chem.,1976, 38. 799.
23 . E.E. Snell , Vitamins. Hormones, 1958, 16, 78.
24. J. Baddi ley , Nature 1952, 170, 711.
25. G.L. Eichhorn and J.W. Dawes , J. Am. Chem. Soc, 1954. 76. 5663 .
26. G.L. Eichhorn and J.W. Dawes . J. Am. Chem. Soc, 1956. 78. 2688 .
27. H.N. Chr i s tensen and S.Col l ins . J. Biol. Chem., 1956 220 279.
I Chapter References 40
28.
29.
30.
31 .
32.
34.
35.
37.
38.
39.
40.
41.
42.
A. Nakahara, H. Yamamoto and H. Matsumoto, Bull. Chem. Soc. Jpn., 1964, 37,1137.
M. Kishita, A. Nakahara and M. Kubo, Aust. J. Chem. Soc. Jpn.. 1964, 37, 1 137.
M. Singh, Synth. React. Inorg. Met.-O Chem., 1985, 15, 235.
M. Nath, C.L. Sharma ar ' Met.-Org. Chem.. 1991 N
M. Nath and P 1993. 23, 1«'
E L . Muettv
B. Chaudret, 1988. 86, 191
A.L. Balch, R.l Chem., 1985, 24
t>
1 - "5
^ T. V "
Synth. React. Inorg
Met.-Org. Chem.
9, 79, 479.
Chem. Rev.
and F.E. Wood, Inorg.
J.P. Farr, M.M. C ...stead and A.L. Balch, J. Am. Chem. Soc, 1980. 102. 6654.
J.P. Farr, M.M. Olmstead, C.H. Hunt and A.L. Balch, Inorg. Chem., 1981, 20. 1 182
A. Maisonnat. J.P. Farr, M.M. Olmstead, C.H. Hunt and \ .L. Balch. Inorg. Chem., 1982, 21, 3961.
J.P. Farr. M.M. Olmstead. F.E. Wood and A.L. Balch, J.Am. Chem. Soc, 1983. 105, 792.
M.A. Ciriano, J.J. Perez-Torrente, F.J. Lahoz and L.A. Oro. Inorg. Chem., 1992. 31. 969.
P.D. Boyle, D C . Boyd. A.M. Mueting and L.M. Pignolet, Inorg. Chem., 1988. 27, 4424.
B.D. Alexander, M P . Gomez-Sal. P.R. Gannon. C.A. Blaine, P.D. Boyle, A.M. Mueting and L.H. Pignolet, Inorg. Chem., 1988. 27. 3301.
Chapter 1 References QD
43. R.P.F. Ranters. J.J. Bour, P.P.J. Schlebos, W.P. Bosman, H.J. Behn and J.J. Steggerda, Inorg. Chem., 1988, 27, 4034.
44. L.N. Ito. B.J. Johnson, A.M. Mueting and L.H. Pignolet, Inorg. Chem., 1986, 28. 2026.
45. Z. Karpinski, ./. Catal., 1982, 77, 118.
46. O. Kahn, Struct. Bonding (Berlin), 1987, 68, 89.
47. Y.Journaux, J. Sletten and 0 . Kahn, Inorg. Chem., 1986. 25, 439.
48. Y. Pei, Y. Journaux. O. Khan, A. Dei and D. Gatleshi, J. Chem. Soc. Chem. Commun., 1986, 1300.
49. Y. Pei, J. Sletten and O. Kahn, J. Am. Chem. Soc, 1986, 108, 3143.
50. A. Benclm, C. Benelli. D. Gatteshi, C. Zanchini, A.C. Fabretti and G.C. Franchini. Inorg. Chim. Acta., 1984, 86, 169.
51. Y. Pei. M. Verdaguer. O. Kahn, J. Sletten and J.P. Renaud. Inorg. Chem., 1987. 26. 138.
52. M. Verdaguer. M. Julve. A. Michalowicz and O Kahn, Inorg. Chem., 1983, 22. 2624.
53. A.C. Fabretti. A.Giusti. V.G. Albano, C. Castellan, D. Gatteschi and R Sessoli, J. Chem. Soc. Dalton Trans., 1991, 2133.
54. J. Casabo. J. Pons. K.S. Siddiqi, F. Teixidor. E. Molins and C. Miravitlles. J. Chem. Soc. Dalton Trans., 1989, 1401.
55. N.F. Curtis. J. Chem. Soc, 1960. 4409
56. M.C. Thompson and D.H. Busch, J. Am. Chem. Soc, 1964, 86. 3651.
H.E. Simmons and C.H. Park, J. Am. Chem. Soc, 1968. 90. 2428.
Chapter 1 References ] GH
58. M.W. Hosseini and J.M. Lehn, Helv. Chim. Acta., 1988, 71, 749.
59. R.J. Motekaitis and A.E. Martell, Inorg. Chem., 1992. 31. 5534.
60. A. Bencini, A. Bianchi. M.l. Burguete, P. Dapporto, A. Domench, E.G. Espana, S.V. Luis, P. Paoli and J.A. Ramirez, J. Chem. Soc. Perkin Trans., 1994, 2, 569.
61. I.M. Helps, D. Parker, J R . Morphy and J. Champan, Tetrahedron 1989. 45. 219.
62. M.K. Moi, C.F. Meares, M.J. McCall, W.C. Cole and S.J.D. Nardo, Anal. Biochem., 1985, 148, 249.
63. A. Albert "Selective Toxicity", Champan and Hall., London 1973.
64. V. Prelog, "Pharmaceutical Chemist}", Butterworth Scientific Publications 1962. 327.
65. D. Parker, Chem. Soc. Rev., 190, 19, 271.
66. C. Brewer, G. Brewer, L. May, J. Sitar and R. Wang, J. Chem. Soc. Da!ton Trans., 1993, 51.
67. S.L. Lambert and D.N. Hendrick, Inorg. Chem., 1979, 18, 2683.
68. M. Beley, J.P. Collin, R. Ruppert and J.P. Sauvage, J. Chem. Soc. Chem. Commun., 1984, 1355.
69. E Kimura, M. Haruta, T. Koike, M. Shionnoya, K. Takenouchi and Y. Litaka, Inorg. Chem., 1993. 32. 2779.
70. J.J.R. Frausto de Silva and R.J.P. Williams, "The Biological Chemistry of the Elements ", Clarendon Press, Oxford, 1991.
71. D. Vorlander and Justus Diebigs, Ann. Chem., 1894,280, 167.
72. W.H. Carothers and G.L. Dorough, ./. Am. Chem. soc, 1930, 52, 711.
Chapter 1 References 43]
73. E.W. Spanagel. French patent 1936, 796, 410.
74. A. Baeyer, Be r , 1886, 19, 2184.
75. L.F. Lindoy and D.H. Busch, In "Preparative Inorganic-Reactions",. IV. L. Jolly, Ed. Wiley-lnterscience:'Ne\K York 1971, 6, 1.
76. K. Ziegler, H. Eberle and H. Ohlinger, Liebigs Ann., 1993, 504, 94.
77. M.P. Suh, W. Shin, D. Kim and S.Kim, Inorg. Chem., 1984, 23, 618.
78. S. Chandrashekhar and A. McAuley, Inorg. Chem., 1992, 31, 2234.
79. G.A. Melson. Ed. "Coordination Chemistry of Macrocyclic Complexes", Plenum. New York, 1979.
80. D.A. House and N.F. Curtis, Chem. Ind., 1961. 1708.
81. D.E. Fenton, Pure Appl. Chem., 1986, 58, 1437.
82. D. Sellman and L. Zapf. Angew, Chem. Int. Ed. Engl, 1984. 23, 807.
83. B.N. DieL R.C. Haltiwanger and A.D. Orman, J. Am. Chem. S o c , 1982, 104. 4700.
84. S.M. Nelson. S.G. McFall, M.G.B. Drew and A. Hamid bin Othmann, Proc. R. Ir. Acad. Sect., B. 1977, 77, 523.
85. D.H. Cook and D.E. Fenton. J. Chem. Soc. Dalton Trans., 1979, 266.
86. D.E. Fenton, Pure Appl. Chem., 1986, 58, 1437.
87. S.M. Nelson, Pure Appl. Chem., 1980, 52. 2461.
88. D.E. Fenton, D.H. Cook, I.W. Nowell and P.E. Walker, J. Chem. Soc. Chem. Commun., 1978. 279.
Chapter 1 References | 44
89. D.E. Fenton, D.H. Cook and I. W. Nowell, J. Chem. Soc. Chem. Commun., 1977, 274.
90. M.G.B. Drew, A Rodgers, M. McCann and S.M. Nelson, J. Chem. Soc. Chem. Commun., 1978, 415.
91. D.E. Fenton, D.H. Cook, M.G.B. Drew, S.G. McFall and S.M. Nelson, J. Chem. Soc. Dallon Trans., 1977, 446.
92. M.G.B. Drew, A. Hamid bin Othmann, S.G. McFall, P.D.A. Mcllroy and S.M. Nelson, J. Chem. Soc. Dahon Trans., 1977. 1173.
93. S.M. Nelson and D.H.Busch, Inorg. Chem., 1969, 8, 1859.
94. S.M. Nelson, P. Bryan and D.H. Busch, J. Chem. Soc. Chem. Commun., 1966, 641.
95. M.G.B. Drew and S M. Nelson, Acta Cryslallogr., 1975, A31, S 140.
96. E. Fleischer and S. Hawkinson, J. Am. Chem. Soc, 1967, 89, 720.
97. A.J. Rest, S.A. Smith and I.D. Tyler, Inorg. Chim. Acta., 1976, 16, L 1.
98. J. Cabral, M.F. Cabnal, M.G.B. Drew, A. Rodgers, M. McCann and S.M. Nelson. Inorg. Chim. Acta.. 1978, 30, L 313.
99. D.H. Cook. D.E. Fenton. M.G.B. Drew, A. Rodgers, M. McCann and S.M. Nelson. J. Chem. Soc. Dahon Trans., 1979, 414.
100. D.H. Cook and D.E. Fenton, J. Chem. Soc. Dahon Trans., 1979, 810.
101. J.L. Sessler, M.J. Johnson and V. Lynch, J. Org. Chem., 1987, 52, 4394.
102. M.G.B. Drew, J. Nelson and S.M. Nelson. J. Chem. Soc. Dahon Trans., 1981, 1678.
Chapter 1 References | 1 45
103. L.F. Lindoy and D.H. Busch, Inorg. Nuclear Chem. Letters, 1969, 5, 525.
104. L.G. Armstrong and L.F. Lindoy, Inorg. Nuclear Chem., 1974, 10, 349
105. L.F. Lindoy, B.W. Skelton. S.V. Smith and A.H. White, Ausl. J. Chem., 1993, 46. 363.
106. L.F. Lindoy, Chem. Soc. Rev., 1975, 421.
107. K.R. Adam, A.J. Leong, L.F. Lindoy, H.C. Lip, B.W. Skelton and A.H. White. J. Chem. Soc, 1983, 105, 4645.
108. K.R. Adam, K.P. Dancey, A.J. Leong, L.F. Lindoy, B.J. McCool, M. Mcpartlin and P.A. Tasker, J. Chem. Soc. Chem. Commun., 1986, 1011.
109. K.R. Adam, M. Antolovich, D.S. Baldwin, P A . Duckworth. A.J. Leong, L.F. Lindoy, M. Mcpartlin and P A . Tasker, J. Chem. Soc. Dal ton Trans., 1993, 1013.
110. K.R. Adam, D.S. Baldwin. P.A. Duckworth, L.F. Lindoy. M. Mcpartlin, A. Bashall, H.R. Powell and P.A. Tasker, J. Chem. Soc. Dal ton Trans., 1995. 1127.
111. D.K. Cabbiness and D.W. Margerum, J. Am. Chem. Soc, 1969, 91, 6540.
112. D.K. Cabbiness and D.W. Margerum, J. Am. Chem. Soc, 1970. 92, 2151.
113. H P . Hopkins and A.B. Norman, J. Phys. Chem., 1980, 84. 309.
114. L.F. Lindoy. "The Chemistry of Macrocyclic Ligand Complexes", Cambridge University Press: Cambridge, 1989.
115. I.M. Kolthoff, Anal. Chem., 1979, 51, IR-22R .
116. M. Kodama and E. Kimura, J. Chem. Soc Dalton Trans., 1979. 325.
Chapter 1 References 46
117. A. DeBlas, G.D. Santis, L. Fabbrizzi, M. Licchelli, A.MM. Lanfredi, P. Marosini, P. Pallavicini and F. Ugozzoli, J. Chem. Soc. Dal ton Trans., 1993, 1411.
118. 1. Tabushi, Y. Taniguchi and H. Kato, Tetrahedron Lett., 1977, 12, 1049.
119. H. Sigel and R.B. Martin, Chem. Rev., 1982, 82, 305.
120. D.H. Busch, Helv. Chim. Acta., Fasciculus Extraordinarius Alfred Werner, 1967, 1974.
121. L.Y. Martin, L.J. Dettayes, L.J. Zomba and D.H. Busch, J. Am. Chem. Soc, 1974, 96, 4046.
122. N.H. Pilkington and R. Robson, Aust. J. Chem., 1970, 23, 2225.
123. S. Brandes, S Lacour, F. Denat, P. Pullumbi and R. Guilard, J. Chem. Soc. Perkm Trans., 1998, 1, 117.
124. D.C.R. Hockless. L.F. Lindoy, G. F. Swiegers and S.B. Wild, J. Chem. Soc. Perkm Trans., 1998, 1, 639.
125. X.H. Bu, D.L. An. Y.T. Chen, M. Shionoya and E. Kimura. J. Chem. Soc. Dal ton Trans., 1995, 2289 and references therein.
126. R.W. Hay, M P . Pujan, B.K. Daskiewicz, G. Ferguson and B.L. Ruhi, J. Chem. Soc. Dal ton Trans., 1989, 85.
127. H.E. Tweed, N.W. Alcock. N. Matsumoto, P.A. Padolik, N.A. Stephenson and D.H. Busch. Inorg. Chem., 1990, 29, 616.
128. Y. Baran, G.A Lawrance and E.N. Wilkes, Polyhedron 1997, 16, 602.
129. X.H. Bu, D.L. An. X.C. Cao, Y.T. Chen, M. Shionoya and E. Kimura, Polyhedron 1996, 15, 161.
130 S. Chaves, A. Cerva and R. Delgado. J. Chem. Soc. Dalton Trans., 1997, 4181.
Chapter 1 References 47
131. C M . Che and W.K. Cheng, J. ("hem. Soc. Chem. Commun., 1986, 1443.
132. R.S. Drago, B.B. Cordon and C.W. Barnes, J. Am. Chem. Soc, 1986, 108, 2453.
133. N.W. Alcock, P. Moore, HA.A. Omar and C.J. Reader, J. Chem. Soc. Dal ton Trans., 1987, 2643.
134. J.S. Rybka and D.W. Margerum, Inorg. Chem., 1980, 19, 2784.
135. F. Vellaccio, R.V. Puzar and D.S. Kemp, Tetrahedron Lett., 1977, 6, 547.
136. M. Shakir, K.S. Islam. A.K. Mohamed and N. Jahan, Transition Met. Chem., 1997. 22, 189.
137. M. Shakir, S.P. Varkey, F. Firdaus and P.S. Hameed, Polyhedron 1994. 13, 2319.
138. M. Shakir, O.S.M. Nasman, A.K. Mohamed and S.P. Varkey, Polyhedron 1996. 15, 2869.
139. M. Shakir, A.K. Mohamed, O.S.M. Nasman and S.P. Varkey, Synth. React. Inorg. Mel.-Org. Chem., 1996, 26(5), 855.
140. M. Shakir, A.K. Mohamed and O.S.M. Nasman, Polyhedron 1996, 15, 3487.
141. T.A. Khan. S.S. Hasan, S.P. Varkey, M.A. Rather and M. Shakir, Transition Met. Chem.. 1996, 21, 283.
142. T.A. Khan, S.S. Hasan, S.P. Varkey, M.A. Rather, N. Jahan and M. Shakir, Transition Met. Chem., 1997, 22, 4.
143. H.S. Mountford. D.B. Macqueen, A. Li. J.W. Otvos, M. Calvin, R.B. Frankel and L.O. Spreer, Inorg. Chem., 1994, 33, 1748.
144. N. Matsumoto. A. Hirano and A.Ohyoshi. Bull. Chem. Soc. Japan 1983. 56, 891.
145. M.P. Suh and S.K. Kim, Inorg. Chem., 1993, 32, 3562.
Chapter 1 References i ra
146. D.E. Fenton, Adv. Inorg. Bioinorg. Mech., 1983, 21, 817.
147. A. McAuley and C. Xu, Inorg. Chem., 1992, 31, 5549.
148. M P . Suh, G.Y. Kong and I.S. Kim, Bull. Korean Chem. Soc, 1993, 14, 439.
149. M. Shakir, A.K. Mohamed, O.S.M. Nasman and S.P. Varkey, Indian J. Chem., 1996, 35A, 935.
150. P. Comba and P. Hilfenhaus, J. Chem. Soc. Dalton Trans., 1995, 3236.
151. S.V. Rosotha, Y.D. Lampeka and I. Maloshtan, J. Chem. Soc. Dalton Trans., 1993, 631.
152. I. Murase, K. Hamada, S. Uenno and S. Kida, Synth. React. Inorg. Met.-Org. Chem., 1983, 13, 191.
153. G. Reid and M. Schroder, Chem. Soc. Rev., 1990, 19, 239.
154. M.M. Bernardo, M.J. Heeg, R.R. Schroeder, L.A. Ochrymowycz and D.B. Rorabacher, Inorg. Chem., 1992. 31, 191.
155. G.L. Rothermel, L. Miao, A.L. Hill and S.C. Jackels, Inorg. Chem., 1992, 31, 4854.
156. M.G.B. Drew, P.C. Yates. F.S. Esho. J.T. Grimshaw, A. Lavery, K.P. Mckillop, S.M. Nelson and J. Nelson, J. Chem Soc. Dalton Trans., 1988, 2995.
157. L.F. Lindoy and D.H. Busch. Chem. Commun., 1968, 1589.
158. M.C. Thompson and D.H. Busch, J. Am. Chem. Soc, 1964. 86. 3561.
159. L.F. Lindoy and D.H. Busch, J. Am. Chem. Soc, 1969, 91, 4690.
160. E L . Blinn and D.H. Busch, Inorg. Chem., 1968, 7, 820.
161. V. Katovic, L.T. Taylor and D.H. Busch. Inorg. Chem., 1971 10, 458.
Chapter 1 References ] GI
162. V. Katovic, L.T. Taylor and D.H, Busch., J. Am. Chem. Soc, 1969, 91, 2122.
163. D. Funkemeier and Rainer Mattes, J. Chem. Soc. Dalton Trans., 1993, 1313.
164. R.W. Matthews, M. Mcpartlin and J. Scowen, J.Chem. Soc. Dalton Trans., 1977, 2861.
165. G.A. Lawrance, M. Moeder and E.N. Wilkes, Rev. Inorg. Chem., 1994, 13, 199.
166. G. Wei, C.C. Allen, T.W. Hamsle, G.A. Lawrance and M. Moeder, J. Chem. Soc. Dalton Trans., 1995, 2541.
167. K.R. Adam, M. Antolovich, D.S. Baldwin, P.A. Duckworth, A.J. Leong, L.F. Lindoy, M.Mcpartlin and P.A. Tasker, J. Chem. Soc. Dalton Trans., 1993, 1013.
168. M. Shakir and S.P. Varkey. Polyhedron 1994, 15, 791.
169. M. Ahearn, J. Kim, A.J. Leong, .F. Lindoy, O.A. Mathews and G.V. Meehan, J. Chem. Soc. Dalton Trans., 1996. 3591.
170. S.G. Murray and F.R. Hartley, Chem. Rev., 1981, 81, 365.
171. E.I. Solomon, K.W. Penfield and D.E. Wilcox, Struct. Bonding (Berlin) 1983, 53, 1.
172. L. Escriche, M. Almajano and J. Casabo. Polyhedron 1996, 15. 4203.
173. E. Sinn and C M . Harris. Coord. Chem. Rev.. 1969, 4, 391.
174. M.D. Hobday and T.D. Smith, J. Chem. Soc, A, 1971, 1453.
175. T.N. Srivastava, A.K.S. Chauhan and M. Agarwal. Transition Met. Chem., 1978, 3, 378.
176. M.S. Holt, W.L. W'ilson and J.H. Nelson, Chem. Rev., 1989, 89, 11 and references therein.
Chapter 1 References ] d
177. J.D. Donaldson, Prog, lnorg. Chem., 1968, 8, 287.
178. M.P. Johnson, D.F. Shriver and S.A. Shriver, J. Am. Chem. Soc, 1966, 88, 1588.
179. P.G. Harrison and J.J. Zuckerman, J. Am. Chem. Soc, 1970, 92, 2577.
180. T.S. Dory, J.J. Zuckerman and C.L. Barnes, J. Organomet. Chem., 1985, 281, C 1.
181. E.H. Brooks and R.J. Cross, J. Organomet. Chem. Rev., 1970, 6A, 227.
182. D. Cunningham, J. Fitzgerald and M. Little, J. Chem. Soc. Dalton Trans., 1987, 2261.
183. N. Clarke, D. Cunningham, T. Higgnis, P. McArdle, J. McGinley and M.O.'Gara, J. Organomet. Chem., 1994, 33, 469.
184. B. Clarke, D. Cunningham, J.F. Gallagher, T. Higgnis, P. McArdle, J. McGinley, M.N. Cholchuin and D. Sheerin, J. Chem. Soc. Dalton Trans., 1994, 2473.
185. D. Cunningham and J. McGinley, J. Chem. Soc. Dalton Trans., 1992, 1387.
186. C. Floriani and F. Calderazzo, J. Chem. Soc, A, 1969, 946.
187. D. Cunningham, J.F. Gallagher, T. Higgins, P. McArdle, J. McGinley and M.O.'Gara, J. Chem. Soc. Dalton Trans., 1993. 2183.
188. K.S. Siddiqi, F.M.A.M. Aqra, S.A. Shah. S.A.A. Zaidi, J. Casabo and F. Teixidor, Polyhedron 1993. 12, 949.
189. K.S. Siddiqi, F.M.A.M. Aqra, S.A. Shah and S.A.A. Zaidi, Transition Met. Chem., 1994, 19, 305.
190 K.S. Siddiqi. F.M.A.M. Aqra, S.A. Shah and S.A.A. Zaidi. Synth. React. Inorg. Met.-Org. Chem., 1993. 23, 1435.
Chapter 1 References i an
191. H. Milburn, M.R. Truter and B.L. Vichery, J. Chem. Soc. Dal ton Trans., 1974, 841.
192. M. Calligaris, L. Randaccio, R. Barbieri and L. Pellerito, J. Organomet. Chem., 1974, 76, C 56.
Chapter 2 Instruments Used | | 53
INSTRUMENTS USED
2.1 IR SPECTROSCOPY
T •he IR spectra (4000-200 cm"1) were recorded as
KBr discs on an IR 408 Shimadzu
spectrophotometer. Some of the important group
frequencies in the IR spectra pertinent to the discussion of
the newly synthesized compounds are:
(i) N-H stretching frequency
(ii) C-N stretching frequency
(iii) C=N stretching frequency
Chapter 2 Instruments Used 54
(iv) Sn-N stretching frequency
(v) M-N stretching frequency
(vi) M-0 stretching frequency
(vii) M-Cl stretching frequency
(viii) M-S stretching frequency
(ix) Amide bands
2.2 *H NMR SPECTROSCOPY
'H NMR spectra in d6 -DMSO using a Bruker AC 200 E and
Bruker FX -100 FT nuclear magnetic resonance spectrometer with
Me4Si as an internal standard were obtained from GNDU, Amritsar
and IIT, New Delhi, India. All the samples were recorded at room
temperature (22-24 °C). All the factors connected with the recording
of the spectra were taken care off. The frerquency used was around
200 MHz.
2.3 EPR SPECTROSCOPY
EPR spectra of all the copper complexes were recorded on a
Jeol JES RE2X EPR spectrometer at room temperature from the
Physics Department, Aligarh Muslim University. Aligarh, India. The
gll , gi and G values were calculated from these spectra.
Chapter 2 Instruments Used QE
2.4 UV - VIS. SPECTROSCOPY
Electronic spectra (10*3 M solution) in DMSO were recorded on
a Pye-Unicam 8800 (Philips, Holland) UV-vis. spectrophotometer at
room temperature from the Instrumentation centre, Aligarh Muslim
University, Aligarh. India.
2.5 MAGNETIC SUSCEPTIBILITY MEASUREMENTS
Magnetic susceptibility measurements were determined at
25°C using a Faraday balance calibrated with Hg[Co(NCS)4] . When
magnetic susceptibility is considered on the weight basis, the gram
susceptibility (xg) is used instead of volume susceptibility. The u.eff
value was calculated from the gram susceptibility multiplied by the
molecular weight and corrected for diamagnetic values as
^ e f f = 2 - 8 4 V X M C , " T . B.M.
Where T is the absolute temperature at which the
experiment is performed. The gram susceptibility is measured by the
formula
_ AW W s t d
W AWstd
Chapter 2 Instruments Used 56
where
AW
W
Wstd
^s td
Gram susceptibility
Change in weight of the unknown sample with magnet
on and off.
Weight of the known sample.
AWstd = Change in weight of standard sample with magnet on
and off.
Weight of standard sample.
Gram susceptibility of the standard sample.
2.6 MOLAR CONDUCTANCE MEASUREMENTS
Electrical conductivity data 10" M solutions in DMSO were
obtained with a Systronic type 302 conductivity bridge thermostated
at 25 ± 0 . 1 °C. The molar conductance (Am) which is related to the
conductance value is calculated by
Cell constant x Conductance Ar
Concentration of solute expressed in mol cm"3
Chapter 2 Instruments Used 57
2.7 ELEMENTAL ANALYSES
The results of elemental analyses for carbon, hydrogen and
nitrogen were carried out with a Thomas and Coleman analyser,
Carlo Erba 1108 from CDRI, Lucknow, India. Metals and Chloride
were determined volumetrically and gravimetrically, respectively by
standard methods. For the metal estimation a known amount of
complex was decomposed with mixture of nitric, perchloric and
sulphuric acids in a beaker. It was then dissolved in water and made
upto a known volume followed by volumetric titration with standard
EDTA. For Chloride estimation a known amount of the sample was
decomposed in a platinum crucible and dissolved in water with a
little concentrated nitric acid. The solution was then treated with
silver nitrate solution. The precipitate was dried and weighed.
CHAPTER-3 This chapter deals Mith the basic experimental procedures, reagents used to perform the synthesis of various complexes and their results and discussion.
Chapter 3 Heterobimetallic Complexes 59
3.1
SYNTHESIS AND SPECTROSCOPIC STUDIES OF HETEROBIMETALLIC COMPLEXES
3.1.1 INTRODUCTION
There are a variety of synthetic methods available for the
formation of transition metal-tin bonds and several excellent
reviews' 4 have appeared on the studies of transition metal-tin
complexes during the past few years. The complexation behaviour of
tetradentate transition metal chelates to act as effective bidentate
donor ligands to tin(IV) halides, organotin(IV) halides and
pseudohalides are well investigated5"9. One of the specific interest in
1:1 adducts of tin-transition metal Schiff-base complexes lies with
Chapter 3 Heterobimetallic Complexes 60
the fact that the dioxygen carrying properties of transition metal
Schiff-base complexes are altered when act as donor ligands to tin .
This part of the chapter describes synthesis of a new series of tin-
transition metal complexes with a view to study the ligating
behaviour of the tetradentate ligands towards transition metal and
non-transition metal ions simultaneously.
3.1.2 MATERIALS AND METHODS
The metal salts, NiCl2 .6H20, CoCl2 .6H20, MnCl2 .4H20,
CuCl 2 .2H 20 and ZnCl2 were of BDH quality. Benzil. 1-2-
diaminoethane, 1,3-diaminopropane, 2,4-pentanedione and tin(IV)
tetrachloride (all E.Merck) were used as received. The solvents,
methanol and dimethylsulphoxide were commercially available pure
samples and were dried before use.
Dichloro(l,2-diphenylethane-l,2-dione bis 1,2-diamino-
ethane)metal(II)-dichlorotin(IV),[MCI2L1SnCl2]; dichloro (1,2-
diphenylethane-1,2-dione bis l,3-diaminopropane)metal(II)-
dichlorotin(IV), [MCI2L2SnCl2] [M = Mn", Co", Ni", Cu11 and
Zn"j.
Chapter 3 Heterobimetallic Complexes ] EH
A mixture of 1,2-diaminoethane or 1,3-diaminopropane (0.67,
0.74 cm ,10 mmol) and benzil (1.05 gm, 5 mmol) in methanol (50
cm ) was taken in a round bottomed flask and stirred with gentle
heating for about 15 min. Then a hot methanolic solution (50 cm ) of
metal(II) chloride (5 mmol) was added followed by the addition of
tin(IV) chloride (1.3 gm. 5 mmol) in methanol (50 cm3). The addition
of tin(IV) chloride showed a gradual change in colour of the solution
either into more light colour or into a new colour. The final mixture
was stirred for another 7 hrs. and the resultant product thus obtained
was filtered, washed several times with methanol and dried in vacuo.
Dichloro(l,3-dimethylpropane-l,3- dione bis 1,2-diamino-
ethane)metal(II)-dichlorotin(IY), |MCl2L3SnCl2]; dichloro(l ,3-
dimethyl-propane-l,3-dione bis l,3-diaminopropane)metal(II)-
dichlorotin(IV), [MCl2L4SnCI2]lM = Mn", Co", Ni", Cu" and
Zn11].
These compounds have been prepared by adopting the same
procedure as described above. Here instead of benzil the diketone
2,4-pentanedione (0.51 cm3. 5 mmol) was employed for the
condensation of the amine moiety, but the addition of tin(lV)
chloride showed a sudden change in colour of the solution.
Chapter 3 Heterobimetallic Complexes 62
3.1.3 RESULTS AND DISCUSSION
The reaction of 1,2-diaminoethane or 1,3-dia-
minopropane, with diketones (benziL 2,4-pentanedione) in presence
of transition metal salts and tin(lV) chloride in 2:1:1:1 molar ratio
gave a new series of heterobimetallic complexes exhibiting the
stoichiometry [MCl2LSnCl2] [M = Mn", Co", Ni", Cu11 and Zn11; L
= L! - L4] as shown in Scheme 6. All the complexes are stable to
atmosphere at room temperature. These adducts have very low
solubility in organic solvents but are freely soluble in polar solvents
such as dimethylformamide, dimethylsulphoxide and acetonitrile. All
the complexes were found to give higher yields (53-68%). The
elemental analyses (Table 1) results are acceptable with the proposed
stoichiometry of the adducts. The molar conductance values in
dimethylsulphoxide (DMSO) measured for all the compounds are
found to be low and are consistent11 with the non-electrolytic nature
of these compounds.
The prominent IR spectral results of the compounds are given
in the Table 2. The main feature of the IR spectra is the appearance
of a band around 1600 cm'1 which can be unambiguously assigned to
the azomethine linkage v(C=N) and is consistent12 with coordinated
imine bonds. This information along with the absence
Chapter Heterobimetallic Complexes ] [
z 5
?• r,— z- 5
I A / •z z .
H
X. x a.
A/X x o * o x
c
c
\ / c in
*£ ^
S ^ * ° x
/ \ z z
M x CL a.
\ /
c
.A . C \ ~\ -> £"c * a o x
v/ \y
c
•9 C C!
""3
o U
<s f } «s f» -II II II II -
= = = = II »- •* r- »•
J J J J S
Table 1. % yield, Colour, Melting point, Molar Conductance and Analytical Data for the Compounds.
Found (Calc.)% Compound % Yield Colour Melting Am
Point (cm ft mol ) c H N M Cl Sn
TO
[MnCl 2 L 1 SnCl 2 ] 65 Moon m i s t 300 1 9 . 7 3 9 . 8 4 . 2 1 0 . 7 1 0 . 2 1 3 . 5 2 1 . 7 ( 4 0 . 2 ) ( 3 . 7 ) ( 1 0 . 4 ) ( 1 0 . 2 ) ( 1 3 . 2 ) ( 2 2 . 1 )
[MnCl 2 L 2 SnCl 2 ] 63 G r e y s t o n e 2 4 1 - 2 4 3 1 4 . 5 4 3 . 0 4 . 5 1 0 . 3 9 . 5 1 3 . 0 2 0 . 6 ( 4 2 . 5 ) ( 4 . 3 ) ( 9 . 9 ) ( 9 . 7 ) ( 1 2 . 5 ) ( 2 1 . 0 )
[MnCl 2 L 3 SnCl 2 ] 65 Cream 263 1 9 . 5 2 4 . 9 4 . 2 1 3 . 6 1 3 . 3 1 7 . 0 2 8 . 1 ( 2 5 . 3 ) ( 4 . 3 ) ( 1 3 . 1 ) ( 1 2 . 9 ) ( 1 6 . 6 ) ( 2 7 . 8 )
[MnCl 2 L 4 SnCl 2 ] 62 C o l o u r l e s s 2 6 1 1 6 . 1 2 9 . 5 4 . 5 1 1 . 9 1 1 . 8 1 5 . 9 2 5 . 8 ( 2 9 . 0 ) ( 4 . 9 ) ( 1 2 . 3 ) ( 1 2 . 1 ) ( 1 5 . 6 ) ( 2 6 . 1 )
[ C o C l 2 L J S n C l 2 ] 68 Dim b u r n o u s 252 2 4 . 6 4 0 . 2 4 . 0 1 0 . 1 1 1 . 1 1 2 . 8 2 2 . 1 ( 4 0 . 0 ) ( 3 . 7 ) ( 1 0 . 4 ) ( 1 0 . 9 ) ( 1 3 . 1 ) ( 2 2 . 9 )
[CoCl2L2SnCl2] 67 Lead grebe 231 18.6 42.7 4.1 10.3 10.7 12.3 21.3
(42.2) (4.2) (9.8) (10.3) (12.4) (20.8)
[CoCl2L3SnCl2] 68 Sonore 253 15.5 24.8 4.4 12.7 14.3 17.0 28.1
(25.1) (4.2) (13.0) (13.7) (16.5) (27.6)
[CoCl2L SnCl2] 65 Sponge >340
[NiCl2L1SnCl2] 57 Light green 160 19
[NiCl2L\SnCl2] 54 Light green 258
[NiCl2L SnCl2] 57 Light green 23! 17
[NiCl2L SnCl2] 53 Light green 25! 12
[CuC]2L SnCl2] 59 Sky blue 2 62
[CuCl2L SnCl2] 61 . Aqua green 219 12
[CuCl2L SnCl2] 59 Sky blue 267 10
29.3 5.1 11.8 (28.8) (4.8) (12.2)
40.4 3.8 10.2 (40.0) (3.7) (10.4)
41.8 4.0 10.3 (42.2) (4.2) (9.8)
24.8 4.5 12.5 (2 5.1) (4.2) (13.0)
29.1 4.6 11.8 t28.8) (4.4) (12.2)
40.1 3.5 10.0 (39.6) (3.7) (10.3)
42.0 4.5 10.1 (41.9) (4.2) (9.8)
25.0 4.3 13.2 (24.8) (4.2) (12.9)
13.2 15.5 26. 1 (12.8) (15.4) (25.9)
10.3 12.7 22.3 (10.8) (13.1) (21.9)
9.8 12.8 21.3 (10.3) (12.5) (20.9)
14.0 16.9 27.3 (13.6) (16.5) (27.6)
13.1 15.3 25.4 (12.8) (15.5) (25.9)
12.0 13.3 22.1 (11.6) (13.0) (21.7)
10.6 12.8 20.3 (11.1) (12.4) (20.7)
14.8 15.9 28.0 (14.6) (16.3) (27.5)
[CuCl 2 L 4 SnCl 2 ] 56 O c e a n g r e y 266 1 1 . 4
[ Z n C l 2 L 1 S n C l 2 ] 64 O f f - w h i t e 220 1 0 . 4
[ Z n C l 2 L 2 S n C l 2 ] 62 C o l o u r l e s s >340 7 . 6
[ Z n C l 2 J J3 S n C l 2 ] 65 O f f - w h i t e 2 4 9 2 2 . 0
[ZnCl 2 L S n C l 2 ] 60 O f f - w h i t e 320 2 1 . 0
2 8 . 0 5 . 1 1 1 . 8 ( 2 8 . 5 ) ( 4 . 8 ) ( 1 2 . 1 )
3 9 . 0 3 . 3 1 0 . 5 ( 3 9 . 5 ) ( 3 . 7 ) ( 1 0 . 2 )
4 2 . 1 4 . 4 1 0 . 2 ( 4 1 . 7 ) ( 4 . 2 ) ( 9 . 7 )
2 5 . 0 4 . 5 1 3 . 1 ( 2 4 . 7 ) ( 4 . 1 ) ( 1 2 . 8 )
2 8 . 3 4 . 5 1 1 . 8 ( 2 8 . 4 ) ( 4 . 8 ) ( 1 2 . 0 )
1 4 . 1 1 5 . 6 2 6 . 0 ( 1 3 . 7 ) ( 1 5 . 3 ) ( 2 5 . 6 )
1 2 . 0 1 3 . 1 2 2 . 2 ( l l . ' M ( 1 2 . 9 ) ( 2 1 . 7 )
1 1 . 7 1 1 . 9 2 1 . 0 ( 1 1 . 4 ) ( 1 2 . 3 ) ( 2 0 . 6 )
1 5 . 1 1 5 . 7 2 6 . 8 ( 1 4 . 9 ) ( 1 6 . 2 ) ( 2 7 . 1 )
1 3 . 8 1 4 . 8 2 6 . 1 ( 1 4 . 1 ) ( 1 5 . 2 ) ( 2 5 . 5 )
Table 2 . IR S p e c t r a l Da ta (cm ) f o r t h e Compounds.
Compound v(N-H) V(C-H)
[MnCl2L1SnCl2] 3150 2915
[MnCl;>L2SnCJ2] 3165 2 900
[MnCl2L3SnCl2] 3170 2890
[MnCl2L4SnCl2] 3155 2910
[CoCl2L1SnCl2] 3175 2940
[CoCl2L2SnCl2] 3180 2900
[CoCl2L3SnCl2] 3190 2930
[CoCl2L4SnCl2] 3160 2880
V(C=N) V(C-N) v(Sn-N) V(Sn-Cl
1610 1135 380 32C
1600 1120 360 300
1605 1125 390 340
1600 1130 375 360
1610 1120 380 330
1605 1140 365 350
1605 1130 370 335
1600 1135 380 360
) V(M-C1) V(M-N) Ring vibrations
270 440 1430,1090,730
280 450 1445,1085,745
275 465 -
265 435 -
260 455 1425,1085,740
280 450 1440,1060,735
260 460 -
280 450 -
[NiCl2L SnCl2]
[NiCl2L2SnCl2]
tNiCl2L3SnCl2]
[NiCl2L4SnCl2]
[CuCl2L1SnCl2]
[CuCl2L2SnCl2]
[CuCl2L3SnCl2]
[CuCl2L4SnCl2]
[ZnCl2LiSnCl2]
3170 2910
3185 2890
3165 2880
3180 2900
3160 2900
3180 2910
3190 2905
3175 2895
3170 2910
1610 1125
1600 1120
1595 1135
1605 1125
1610 1120
1615 1130
1600 1120
1605 1125
1600 1130
360 350
370 355
3 8 5 3 4 0
375 335
380 320
390 310
375 350
380 315
390 310
275 455
260 440
270 425
280 4 50
260 440
290 460
280 445
260 435
285 455
1410,1055,740
1430,1045,750
1435,1060,765
1420,1075,750
1450,1070,735
[ZnCl2L SnCl2] 3155 2890 1610 1135 365 320 255 440 14 60,1065,730
[ZnCl2L3SnCl2] 3165 2920 1615 1140 390 300 265 265 -
[ZnCl2L4SnCl2] 3180 2925 1595 1125 380 330 280 445 -
Table 3. H NMR Spectral Data* for the Compounds
Compound N-CH2-C C-CH2-C C-CH3-C=N C-NH-Sn N-C6H5-C=N
[ZnCl2L1SnCl2] 3.18(m) - - 6.08(m) 7.47(m)
[ZnCl2L2SnCl2] 3.21 (m) 2.03 (m) - 6.12 (m) 7.52 (m)
[ZnCl2L3SnCl2] 3.19(m) - 2.38(s) 6.14(m)
[ZnCl2L4SnCl2] 3.20(m) 2.11(m) 2.43(s) 6.20(m)
rChemical shifts (5/ppm) with multiplicities in parenthesis S = singlet and m = multiplet
Table 4. fieff Values, Ligand Field Bands observed in the Electronic Spectra (cm1) , their Assignments and EPR Spectral
Parameters for the Compounds.
Compound
[MnCl2L'SnCI2]
[MnCl2L2SnCl2]
[MnCI2L3SnCI2]
[MnCl2L4SnCI2]
^efT.
(B.M.)
5.79
5.77
5.80
5.77
Band position
(cm" )
18600
22100
18900
21500
18550
21900
19100
21300
Assignments EPR data
*M
6 A A l g
6A A i g
T ,g(p) 4T2g(F)
JA,g -+ 4T]g(P)
Llg
klg
6 A
A|g klg
T 2 g ( F )
> «T,g(P)
-» 4T2g(F)
T .g ( p )
[CoChL'SnCh] 4 54 13700
21500
[CoCl2L2SnCl2] 456 13500
21800
[CoCl2L3SnCl2] 4 57 13900
21400
[CoCl2L4SnCl2] 458 14250
21800
[NiCI^ 'SnCb] 3.14 11500
17900
[NiCl2L2SnCl2] 3.15 11600
17700
[NiCl2L-SnCl2] 3.15 11300
17500
4T,g(F) -> 4T |g(F) >
4T |g(F) -> 4T,g(F) - •
4T]g(F) -4T)g(F) -*
4T,g(F) -4 T , g ( F ) ^
' ^ g -> ?A2g ->
A2g -> V2g -»
\ g "»•
\ g -+
4A2g(F) -4T |g(P)
4A2g(F) -4T lg(P)
4A2g(F) -4T lg(P)
4A2g(F) -4T,g(P)
•T,g(F) -
'T,g(P)
V,g(F) -3T,g(P)
3T,g(P)
v© — O
ir, 00 r--
o T 00
o o 00 (N
o
rr 00
u. a. ^ o ^ o *D
SO (N UJ CQ sj rsi
SO
w r~i
oo rsi
CQ I N
ao 50 fN UJ CQ
r>i rvi
00 oo 7i
UJ CQ IN (N
00
< QO 00 00
< CQ CQ
^v * V p, ^^ ^K ^^
00 00 oo oo CQ CQ CO CQ
<N (N
00 00
CQ CQ
o o r-—
^ o cv
r»
o o r-oo
o o 00 I/",
o o •sD 00
o o (N o
o o —. <?•
o o f<"l vO
o © a 00
o o T \£>
00 ON o 00
o 00
c 00
u c
oo J
rv l
o 3 U^
u c oo
r- i -J
rsj
u 3
u
u c oo
r*". J
<N
u 3 V
u c 00
TJ-J
<N
u 3
u
Chapter 3 Heterobimetallic Complexes | | 74
of bands due to carbonyl groups strongly support that the
condensation of primary amine with the carbonyl groups has taken
place. Another important single band appeared around 3170 cm"
assignable to the v(N-H) of amino group. This band shows a marked
negative shift13 in all the complexes indicating coordination through
amino nitrogen. The appearance of band around 1125 cm" for all
the complexes may be attributed to v(C-N) vibration. The
appearance of a sharp band around 450 cm"1 is attributable14 to v(M
N) vibration. All of the tin(IV) chloride adducts exhibit a broad
intense band in the 300-360 cm'1 region which may probably be
associated with the v(Sn-Cl) frequencies. In the 750-900 cm'1 region
of the spectra, there are absorption bands which should arise from
methylene and methyl rocking vibrations together with symmetric C
N streching. A weak intensity absorption band in all the complexes
identified around 380 cm"1 probably be due to v(Sn-N) vibration \
The other fundamental vibrations appeared at their expected
positions.
The 'H NMR spectra (Table 3) of [ZnCl2LSnCl2] adducts
appear to be more complex and do not show any bands assignable to
primary amino protons. All the compounds gave two multiplets
between 6.08 and 6.20 ppm, and between 3.18 and 3.21 ppm which
Chapter 3 Heterobimetallic Complexes ] d
can be assigned16 '17 to the N-H protons (C-NH,2H) and the methylene
(CH2-N, 8H) protons of amine moiety, respectively. The spectra of
[ZnCl2L2SnCl2] and [ZnCl2L4SnCl2] showed a multiplet at 2.03 and
1 7
2.11 ppm, respectively which may be ascribed to the central
methylene (C-CH2-C,4H) protons of 1,3-diaminopropane portion.
However, the broadness of the 2.38 ppm band for the complex
[ZnCl2L SnCl2] may be due to the overlapping of middle methylene
protons of 2,4-pentanedione and 1,3-diaminopropane. A multiplet
appeared for the complexes [ZnCl2L'SnCl2] and [ZnCl2L2SnCl2] at
7.47 and 7.52 ppm and a sharp singlet observed for the complexes
[ZnCl2L3SnCl2] and [ZnCl2L4SnCl2] at 2.38 and 2.43 ppm may
correspond18 to the phenyl ring protons (C-C6H5,10H] and imine
methyl protons (CH3-C=N,6H), respectively.
The powder sample EPR spectra (Table 4) of [CuCl2LSnCl2]
have been recorded at room temperature which showed a single broad
signal with two g values. The absence of hyperfine splitting in these
complexes indicate that the paramagnetic centres are not diluted. It
has been reported that the values gj and gx have been used to
distinguish unambiguously19 between dx2_v, and the dz2 ground states.
For example, for the dx2_vJ ground state the EPR spectrum should give
8 | > gx and v i c e versa for d , ground state. The heterobimetallic
Chapter 3 Heterobimetallic Complexes | | 76
complexes exhibit g | and g± values in the range 2.23 - 2.28 and 2.10 -
2.14, respectively, which suggest an axially distorted octahedral
structure of copper(II) complexes where the unpaired electron is
present in the d , , orbital with 2B, as a ground state term. It should r x . . y 3 i g o
be noted that for an ionic environment gj > 2.3, while for covalent
environment gy < 2.3. The existance of gj values below 2.3 range
suggest the considerable covalent character of these complexes. The
axial symmetry parameter, G is obtained by the relation (g.,-2)/(gx-2),
which measures the exchange interaction between copper centres in
the crystalline solids. If G > 4 the exhange interaction is negligible
and if G < 4 the exhange interaction is considerable. In these
complexes the G values appeared in the range 1.785-2.800
indicating'1 the possibility of considerable exchange interaction.
The electronic spectra (Table 4) of all heterobimetallic
complexes [MnCl2 LSnCl2] exhibit two bands around 18600 and
22100 cm"1 regions corresponding to the 6 A ] g -> 4 T l g (P) and
A i g ""* ^2g(F) transitions, respectivelty, indicating an octahedral
geometry of manganese(II) complexes. Two ligand field bands for the
cobalt complexes in the 13500 - 14250 and 21400 - 21800 cm"1 may
be assigned to the 4 T l g ( F ) -> 4A2 g(F) and 4T, g (F) -> 4 T l g (P)
Chapter 3 Heterobimetallic Complexes i an
transitions, respectivety corresponding to the octahedral geometry
around cobalt. The nickel(II) complexes gave two distinct bands
around 11600 and 17700 cm"1 ascribed to 3A2g - • 3T,g(F) and
A2g ~* 3 ^ i g ^ ^ transitions, respectivety arising22 from octahedral
geometry of the nickel(ll). The electronic spectra of copper(II)
complexes show two bands in the 18600 - 19100 and 15800-16400
cm" regions which may be ascribed to Bjg -» Eg and Bjg -» B2g
transitions, respectivety, attributable to an octahedral geometry
around copper (II).
All the spectra show very strong intense bands in the ultraviolet
region around 38000 cm"1 which may be assigned to n -» iC
transitions of the ligand. The observed magnetic moment values for
all the complexes [MCl2LSnCl2] are also in accordance with the
proposed octahedral structures.
References \ \ 78
REFERENCES
M.I. Bruce,"Comprehensive Organomelallic Chemistry", G. Wilkinson, F.W. Abel and F.G.A. Stone, 1982, 9, 1209.
M.S. Holt, W.L. Wilson and J.H. Nelson, Chem. Rev., 1989, 89, 11 and the references therein.
M. Shakir, S.P. Varkey, O.S.M. Nasman and A.K. Mohamed, Synth. React. Inorg. Met.-Org. Chem., 1996, 26(3), 509.
M. Shakir, P S . Hameed, F. Firdaus and S.P. Varkey, Transition Met. Chem., 1995, 20, 142.
D. Cunningham, J. Fitzgerald and M. little, J. Chem. Soc. Dalton Trans., 1987, 2261 and the references therein.
D. Cunningham, J.F. Gallagher, T. Higgins, P. McArdle, J. McGinley and M.O'.Gara, J. Chem. Soc. Dalton Trans., 1993, 2183.
L. Pellerito. R. Cefalln, A. Giagnzza and R. barbieri, J. Organomet. Chem., 1974, 70, 303.
D. Cunningham and J. Mchinley, J. Chem. Soc. Dalton Trans., 1992. 1387.
T.N. Srivastava, A.K.S. Chauhan and M. Agarwal, Tranistwn Met. Chem., 1978, 3, 378.
D. Cunningham, T. Higgins, B. Kneafsey, P. McArdle and J. Simmie. J. Chem. Soc. Chem. Commun., 1985,231.
W.J. Geary. Coord. Chem. Rev., 1971, 7, 81.
M. Shakir and S.P. Varkey, Polyhedron 1994, 13, 791.
M. Shakir and S.P. Varkey, Polyhedron 1995, 14, 1117.
M. Shakir, S.P. Varkey and T A. Khan, Indian J. Chem., 1995, 34A, 72.
3 References Qi]
A. Varshney and J.P. Tandon, Polyhdedron 1986, 5, 1853.
K. Burgess, D. Lim, K. Kantto and C.Y. Ke, J. Org. Chem., 1994, 59, 2179.
M. Shakir, S.P. Varkey and O.S.M. Nasman, Polyhedron 1995, 14, 1283.
M. Shakir, S.P. Varkey and P.S. Hameed J.Chem. Res., 1993, 11, 442.
M.C. Jain, A.K. Srivastava and P.C. Jain, Inorg. Chim. Acta., 1977, 23, 199.
R.K. Ray and G.B. Kauffman, Inorg. Chim. Acta., 1990, 173, 207.
M. Shakir. S.P. Varkey and P.S. Hameed, Polyhedron 1994, 13, 1355.
A.B.P. Lever, "Inorganic Electronic Spectroscopy", Elsevier, Amsterdam (1984).
Chapter 3 Tetraoxotetraamide Macrocyclic Complexes | [ 80
3.2
SYNTHESIS AND CHARACTERIZATION OF TETRAOXOTETRAAMIDE MACROCYCLIC COMPLEXES
3.2.1 INTRODUCTION
Polyamide macrocycles have received much attention in
view of their biological importance and catalytic applications1"6.
Many of these ligands chelate transition metals as anions via
dissociation of amide protons, giving neutral complexes7"9.Recently
Bu and co-workers have investigated10 the crystal structure of
1,4,7,10 - tetraazacyclotridecane - 11,13 - dione, appended with 8-
methyl-quinolines. and its reactions with copper(II).
Chapter 3 j | Tetraoxotetraamide Macrocyclic Complexes [ \ 81
The structures and properties of macrocyclic dioxotetraamines
are in some respects similar to those of tripeptides. Such ligands
show unique ligating behaviour towards divalent 3d cations with
simultaneous dissociation of two amino groups" . Tripeptides such as
GlyGlyGlyu'u or GlyGIyHis" sh ow similar modes of coordination to
copper through the two terminal donors and the two deprotonated
amide nitrogens in alkaline media. Polyamide macrocycles can in
principle coordinate either through the amide nitrogen or oxygen
atoms. Kaden and Zuberbuhler have concluded15 from potentiometric
studies that the amide nitrogens of GlyHis and HisHis do not co
ordinate to the copper(II) ion. There are other reports' ' which also
indicate that for synthetic peptides, the peptide nitrogens do not
participate in coordination. Following our previous reports on
polyamide macrocycles, this part of the thesis presents the template
synthesis and characterization of novel tetraamide macrocyclic
complexes derived from anthranilic or o-aminobenzoic and succinic
acids with 1,2-diaminoethane and 1,3-diaminopropane.
3.2.2 MATERIALS AND METHODS
Succinic acid, anthranilic acid, 1,2-diaminoethane and
Chapter 3 Tetraoxotetraamide Macrocyclic Complexes ] 1 82
1.3-diaminopropane (Merck) were all used as received. MnX2 .4H20,
CoX2 .6H20, NiX 2 .6H 2 0, CuX2 .2H20 (X = CI or N 0 3 ) , Zn(N03)2
6H20 and ZnCl2 (BDH) were used as received. All the solvents were
dried before use.
Dichloro/nitrato(6:7,14 : 15-dibenzo-5,9,12,16-tetraoxo-l,
4,8,13-tetraazacyclohexadecane)metal(II), [ML5X2] [M = Mn1 ,
Co" , Ni" , Cu" and Zn11; X = CI or N 0 3 ] .
A stirred solution of the appropriate metal salt (10 mmol) in
methanol (50 cm3) was treated with a solution of o-aminobenzoic
acid (2.74 gm, 20 mmol) in methanol (65 cm3) and 1,2-diaminoethane
(0.67 cm3, 10 mmol) in methanol (30 cm3), added simultanenously. A
solution of succinic acid (1.18 gm, 10 mmol) in MeOH (50 cm3) was
then added and the reaction mixture was stirred for several hrs. which
led to the precipitation of a solid product. This was filtered off,
washed with MeOH and vacuum dried.
Dichloro/nitrato(7:8,15:16-dibenzo-6,10,13,17-tetraoxo-l ,
5,9,14-tetraazacycloheptadecane)metal(II) , [ML6X2] [M = Mn",
Co" , Ni" , Cu11 and Zn11; X = CI or N 0 3 ) .
The respective metal salt (10 mmol) dissolved in methanol
(50 cm ) was treated with a solution of o-aminobenzoic acid
(2.74 gm, 20 mmol) in methanol (65 cm3) and 1,3-diaminopropane
Chapter 3 Tetraoxotetraamide Macrocyclic Complexes | | 83
(0.74 cm . 10 mmol) in metahnol (30 cm ), added simultaneosuly. A
gradual colour change was observed. Finally a methanolic solution of
succinic acid (1.18 gm, 10 mmol) was added to the mixture, which
was then stirred for several hrs. The resulting solid product was
removed by filtration, washed with methanol and vacuum dried.
3.2.3 RESULTS AND DISCUSSION
A new series of tetraoxotetraamide macrocyclic
complexes have been prepared via the condensation reaction of o-
aminobenzoic acid with 1,2-diaminoethane or 1,3-diamino-propane
and succinic acid in presence of transition metal ions as templates
(Scheme 7). Attempts to prepare metal-free ligands in methanol or
ethanol led to oily products which could not be isolated and
analysed. The elemental analyses of the complexes (Table 5) are
consistent with their suggested stoichiometrics. The complexes are
generally highly coloured and polycrystalline in nature. They are
obtained in a 52-64% yield and are indefinitely
stable in the solid state. The molar conductances of the complexes in
DMSO are low (Table 5), suggesting that they are non-electrolytes20
An examination of the IR spectra (Table 6) of the complexes
[ML X2] and [ML6X2] show a medium intensity band for v(N-H) in
Tetraoxotetraamide Macrocyclic Complexes
CO^H ^ ( C H ? ) n ^
NH, H,N NH,
MX 2
(CH^COjH),
?
^"-l<" TO] PL,,. A
'N.
A L , n = 2 L6, n = 3 M = Mn", Co", Ni", Cu" a n d Z n " X = CI or N 0 3
Scheme 7
Table 5. % Yield, Colour, Melting point, Molar Conductance and Analytical Data for the Compounds.
Compound % Yield Colour Melting Am Found ( C a l c . ) %
P o i n t (cm2Q V s l X) C H N M CI
<°C)
[MnL 5 (N0 3 ) 2 ] 53 O f f - w h i t e 317 2 0 . 5 4 3 . 4 3 . 7 1 4 . 8 1 0 . 1 ( 4 2 . 9 ) ( 3 . 6 ) ( 1 5 . 0 ) ( 9 . 8 )
[MnL5Cl2] 54 A g a t e g r e y 305 2 4 . 0 4 7 . 3 4 . 1 1 0 . 7 1 0 . 4 1 3 . 7 ( 4 7 . 4 ) ( 3 . 9 ) ( 1 1 . 0 ) ( 1 0 . 8 ) ( 1 4 . 0 !
[MnL 6 (N0 3 ) 2 ] 54 Dove g r e y 247 1 5 . 6 4 4 . 1 3 . 9 1 4 . 5 9 . 4 ( 4 3 . 9 ) ( 3 . 8 ) ( 1 4 . 6 ) ( 9 . 5 )
[MnL6Cl2] 52 Shadow grey 287 13.3 47.9 4.1 11.1 10.3 13.3 (48.4) (4.2) (10.7) (10.5) (13.6!
[ C o L 5 ( N 0 3 ) 2 ] 62 G r e y 304 1 7 . 5 4 3 . 0 3 . 5 1 5 . 2 1 0 . 1 ( 4 2 . 6 ) ( 3 . 5 ) ( 1 4 . 9 ) ( 1 0 . 4 )
4 6 . 8 4 . 1 1 1 . 4 1 1 . 3 ( 4 7 . 0 ) ( 3 . 9 ) ( 1 0 . 9 ) ( 1 1 . 5 ) ( 1 3 . 8 )
4 3 . 5 3 . 4 1 4 . 7 1 0 . 3 4 3 . 6 ) ( 3 . 8 ) ( 1 4 . 5 ) ( 1 0 . 2 )
[ C o L 5 C l 2 ] 57 Dim g r e y 318 1 6 . 4 4 6 . 8 4 . 1 1 1 . 4 1 1 . 3 1 4 . 3
t C o L 6 ( N 0 3 ) 2 ] 56 B r i g h t g r e y 248 1 6 . 4 4 3 . 5 3 . 4 1 4 . 7 1 0 . 3
[CoL 6 Cl 2 ] 58 D u l l g r e y 287 1 7 .
[ N i L 5 ( N 0 3 ) 2 ] 64 L i g h t a s h 335 17
[ N i L 5 C l 2 ] 60 Dim a s h 345 12
[ N i L 6 ( N 0 3 ) 2 ] 63 B r i g h t g r e y 2 8 3 12
[ N i L 6 C l 2 J 61 Sky g r e y 314 14
[CuL 5 N0 3 ) 2 ] 58 B r i g h t g r e e n 204 18
[CuL 5 Cl 2 ] 62 Dim g r e e n 234 21
[ C u L 6 ( N 0 3 ) 2 ] 62 B r i g h t g r e e n 339 2 3
[CuL 6 Cl 2 ] 58 Dim g r e e n 248 24
4 7 . 7 : 4 8 . o)
4 . 0 ( 4 . 2 ;
1 0 . 5 ( 1 0 . 6 )
1 1 . 7 ( 1 1 . 2 )
1 3 . 7 ( 1 3 . 5
4 2 . 5 : 4 2 . 6 ;
3 . 7 3 . 5 '
1 5 . 2 14 .91
1 0 . 7 1 0 . 4
4 6 . 8 4 7 . l ;
4 . 1 3 . 9 )
1 1 . 3 1 0 . 9 )
1 1 . 3 1 1 . 5 !
14 (13
4 3 . 5 ; 4 3 . 6 )
3 . 8 ; 3 . 8 )
1 4 . 7 1 4 . 5 1
1 0 . 5 1 0 . 1 )
4 7 . 6 : 4 8 . i ;
4 . 3 : 4 . 2 ;
1 0 . 4 1 0 . 6 ;
1 1 . 5 ( 1 1 . 2 ;
1 3 . 4 1 3 . 5 )
4 2 . 7 4 2 . 2 ;
3 . 7 3 . 5 ]
1 4 . 4 1 4 . 7
1 0 . 7 ( 1 1 . I !
4 6 . 3 4 6 . 6 )
4 . 0 3 . 9 )
1 1 . 1 ( 1 0 . 8
1 2 . 1 1 2 . 3 )
14 (13
0 7]
4 3 . 5 ; 4 3 . 3 ;
3 . 9 ( 3 . 8 )
1 4 . 5 ( 1 4 . 4 )
1 1 . 1 1 0 . 9 )
4 7 . 5 4 7 . 6 !
4 . 3 4 . 1 ;
1 0 . 4 1 0 . 5 ;
1 1 . 8 1 2 . o ;
13 ] 3
7 4)
[ Z n L 5 ( N 0 3 ) 2 ] 54
[ Z n L 5 C l 2 ] 56
[ Z n L 6 ( N 0 3 ) 2 ] 56
[ZnL 6 Cl 2 ] 54
Oyster white 167
Dirty white 199
Dirty white 249
Oyster white 317
20.0 41.9 (42.1)
18.0 46.3 (46.4)
19.0 42.8 (43.1)
18.5 47.6 (47.5)
3.4 14.5 (3.5) (14.7)
4.0 11.1 (3.9) (10.8)
3.6 14.3 (3.7) (14.4)
4.3 10.7 (4.1) (10.5)
.1 ] . 7 (11.4)
12.8 13.4 (12.6) (13.7)
11.3 (11.2)
12.5 13.8 (12.3) (13.3)
Table 6. IR Spectral Data (cm ) for the Compounds.
Compound V(N-H)
I
[ M n L 5 ( N 0 3 ) 2 ]
[ M n L 5 C l 2 ]
[ M n L 6 ( N 0 3 ) 2 ]
[ M n L 6 C l 2 ]
[ C o L S ( N 0 3 ] 2 ]
[ C o L 5 C l 2 ]
[ C o L 6 ( N 0 3 ) 2 ]
[ C o L 6 C l 2 ]
[ N i L 5 ( N 0 3 ) 2 ]
[ N i L 5 C l 2 ]
[ N i L 6 (N0 3 ) 2 ]
3 2 3 0
3 2 3 5
3 2 1 0
3 2 3 0
3 2 1 0
3 2 0 0
3 2 4 0
3 2 1 0
3 2 3 0
3 2 2 0
3 2 1 0
1 6 7 0
1 6 8 0
1 6 9 0
1 6 9 0
16 60
1 6 9 0
1 6 8 0
1 6 8 0
1 6 9 0
1 6 8 0
1 6 8 0
Amide bands V(M-N)
^1 I£I IV
530 1230 660 430
530 1240 670 420
550 1280 650 420
540 1290 670 400
520 1280 665 430
540 1270 675 420
540 1280 670 410
550 1260 665 420
550 1250 680 410
540 1240 660 440
530 1260 670 430
V(M-C1) Ring vibrations
300 1405,1025,725
290 1415,1045,755
285 1420,1060,775
310 1410,1025,750
305 1400,1030,760
310 1420,1020,740
280 1420,1020,740
290 1410,1020,730
300 1410,1060,720
310 1400,1035,735
300 1420,1025,730
m CM
r L D
0 0
o r H
U0
o *r
O LO
r-U0
oo o i—i
L D
I—1
^r
O
CM
r-o X )
O i—(
o i—1
M 1
L O
oo r-o ^ o t-i
o 0 0
«3"
o oo r-i n
ro o <-< o CM
*!*
m ro r o T
o r H
O i—1
^r
o «r r-o <x> o <—( 0 0
CM
•cr
o oo r-o oo o t H
m o ^r
m m r~ o I D
O i - t
o CM
«3*
O Cn CM
oo 0 0 CM
o I—1
0 0
o CM 00
o en CM
o oo CM
i n G\ CM
o en CM
o o 0 0
o T V
o o «3"
o CM
r
o I—1
T
o oo <=r
o CM
r
o r r
o oo T
O i-H
«T
LO X )
X>
0 0
r-X>
o 0 0 IX)
m m 1X1
o r~ 1X3
o r-<x>
o <x> *x>
o CO X )
o CO
<x>
o r-CM
o 0 0
CM
o CM
CM
O
m CM
O i n
CM
O L n
CM
O
r-CM
O
r-CM
o oo CM
o <3"
m
o 0 0 u 0
o m i n
o m m
o X )
i n
o <=r m
o 0 0
m
o ^ T
m
o M*
m
o cn X)
o cn X>
o CO IX
o r-X>
o r-X)
o CO X)
o r-X )
o 0 0 X)
o en X)
o OO
CM 0 0
O 0 0
C\J 0 0
o i—H
CM 0 0
o o CM 0 0
o sr CM
oo
o < CM 0 0
O O
CM 0 0
o CM CM 0 0
O
oo CM
oo
,—, rsi • H
u D H-l • H
X
r o
o 2: --LO
J 3 U
,—, CM i—1
U m
J 3 U
ro
o 2 — ID
J 3 u
, , IN
<-i
u ID
J 3 u
r o
o 2 ~—-
i n
• J
d N
r , CM r—1
U o->
h-5
d CO
ro
o 2
>x> .J d
N
( ! CM
• H
C) >£>
h J
d N
Table 7. H NMR Spectral Data* for the Compounds
Compound NH-C=0 N-CH2 Phenyl ring C-CH2-C C=0-CH2
[ZnL5(N03)2] 8.41(s) 3.13(m) 6.54(m) - 2.86(s)
[ZnL5Cl2] 8.46(s) 3.11(m) 6.52(m) - 2.83(s)
[ZnL6(N03)2] 8.46(s) 3.12(m) 6.62(m) 2.09 (m) 2.83(s)
[ZnL6Cl2] 8.43(s) 3.13(m) 6.60(m) 2.12(m) 2.84(s)
*Chemical shifts (6/ppm) with multiplicities in parenthesis S = singlet and m = multiplet.
Table 8. \ieff Values, Ligand Field Bands observed in the Electronic Spectra (cm1), their Assignments and EPR Spectral
Parameters for the Compounds.
Compound ^eff.
(B.M.)
Band position
(cm1)
Assignments EPR data
8|
[MnL(N03)2] 5.85 28500
20500
24300
Llg Llg
rtlg *T,Q(P)
6A,g -^ 4T,e(F) lgv
l2g<
[MnLXl2]
[MnLf'(NOi)2]
[MnL6CI2]
5.71
5.76
5.78
29000
19800
24500
29100
20000
24200
28700
21000
24100
llg 4 .
Aig >A,g "> T,g(p) "A Alg
6A Alg <(A Alg 6A Alg
6A Alg (,A Alg (,A Alg
—>
->
—»
-»
—>
—»
—>
T2g(
p)
Aig 4T l g(P) 4T 2 g(F)
4A Alg
4T,g(P) 4T2g(F)
oo oo
t t
^oo ""oo
00 00
t T
"^00 ""Bo
A-t t
££ j - r
8 » < H
T T
^00 ""OO
00 00 00 <N — —
H H H r*", c \ c^
t t t 00 00 00
00 00 00 <N — —
H E- H r , r r *v,
T t T 00 00 00
o o I T ) T —
o o VO O (N
O O <N T •—
O o T f
o ( N
O o r< l -3-—
o o I T )
o CN
o o r-~ TT —
O o f S o <N
o o r—i
(N —
O O v£> ON
—
o o o t-~-(N
o o o (N —
o o u- i O N
> — '
O O m c-~ 04
TI-«r> TT
TJ-
^r T T
r<->
c i
O
<-~>
o H J
o U
(NO
- J O
u
CJ O
J o CJ
rr, O z
>/-l
J
z
u -J
z
a-o o*
V/~>
CN NO
NO vO VO
ON NO t~-
CN CN <N CN
CN
CN
CN
CN
CN
CN
r«1 CN
CN
oo ^ao ^oo fN — —
H F- H
T t t SO 5 0 0 0
oo ^oo ' T o fN — —
H H H f", r*-. r*-,
T T T oo oo oo CM fN CM
<: < < C", r*\ r*\
00 fN W CQ
t t oo oo
CQ CQ fN fN
00 00 7i
W CQ fN fN
t t 0 0 0 0
OQ CQ fN fN
0 0 fN tU CQ
fN fN
T t oo oo
ffl CQ fN fN
OO fN UJ CQ
fN fN
t t oo oo
CQ CQ fN fN
o o rr CN
O © C"> O
O o r—
r«-
o o o CN
o o •3-&
© o — r-~
o o I T ) 00
o ir> vO i r .
O m NO oo
o o o NO
o o 0 0 0 0
© © m vO
© o m 00
© © ON I T !
NO CN 00 ON oo
© 00
o' z
z
fN
3 -J 3
u
o z 3
u 3
Chapter 3 | Tetraoxotetraamide Macrocyclic Complexes | | 94
the 3200-3240 cm"1 region. This band shows a marked negative shift4
in all the complexes which may be due to the coordination of
nitrogen to the metal atom. This is further supported by the
appearance of a new band for v(M-N) in the 400-440 cm"1 region.
Medium to strong intensity bands observed in the ca. 1690, 1540,
1270 and 660 cm"1 region in the spectra of all the complexes may be
assigned to amide I, amide II, amide III and amide IV vibrations,
respectively. The amide I [v(C=0)] band occurs at almost the same
position as in the analogous metal-free macrocycles21, indicating the
non-involvement of carbonyl oxygen in the complexation. All the
chloro complexes have bands at ca. 300 cm"1 assignable to v(M-Cl)
vibration. The nitrate complexes have bands at ca. 1035, 1290 and
1490 cm"1 assigned to Vi. v2, and v3 of monodentate coordinated
nitrate respectively22. The bands corresponding to the phenyl ring
vibrations are observed at their expected positions.
The H NMR spectra (Table 7) of the zinc complexes in
DMSO-</6 solution showed no signals assignable to the carboxylic or
primary amino protons. All the complexes gave a broad signal in the
8.41-8.46 ppm, range assigned to the amide protons (NHCO, 4H). A
multiplet at 6.52-6.62 ppm. in all of the complexes is characteristic
Chapter 3 Tetraoxotetraamide Macrocyclic Complexes 95
of phenyl ring (C6H4, 8H) protons, whilst a singlet at 2.83-2.86 ppm
may be ascribed to the methylene (COCH2, 4H) protons of succinic
acid moiety. A multiplet observed for all the complexes in the 3.11-
3.13 ppm region may be assigned19 to the (CH2N, 4H) methylene
protons. The complexes of "L6" showed an additional multiplet
around 2.12 ppm attributable to the central methylene protons
(CCH2C, 2H) due to propylene bridge.
The room temperature EPR spectra (Table 8) of the
copper(II) [CuL5X2] and [CuL6X2] complexes gave g ( and gx values in
the 2.21-2.26 and 2.11-2.16 regions, respectively. All complexes
gave similar spectra; the absence of hyperfine splitting indicates that
the paramagnetic centres are not diluted. Copper(II) complexes in
which g| > gx are considered to have the unpaired electron in the
• 23 dx, v, orbital . The G parameters, obtained by the relati on
(g«"2) /(gx-2), were in the 1.625-1.909, range suggesting a
considerable exchange interaction between the copper centres24. The
EPR of the cobalt complexes at room temperature gave only a single
broad signal exhibiting gy and gx around at ca. 2.04 and 2.32
respectively, characteristic of d7 cobalt(II) complexes2 5 2 6 .
The electronic spectra (Table 8) of manganese complexes
exhibit three bands at around 29000, 20000 and 24300 cm"1 regions,
Chapter 3 Tetraoxotetraamide Macrocyclic Complexes | | 96
assignable to 6A, -> 4A, , 6A, -> 4T, (P) and ° lg lg ' !g l g v '
6Aj -> 4T2 (F) transitions, respectively, suggesting24 an octahedral
stereo-chemistry of manganese ion. The ligand field transitions of
cobalt complexes have been recognised at around 14500 and 20400
regions, which may unambiguously be assigned as
4Tj (F) -» 4A2 (F) and 4T, (F) ->• 4Tj (P) transitions, respectively in
octahedral symmetry.
The nickel(II) complexes showed the appearance of three
bands around 12100, 19400 and 27100 cm'1 which may be attributed
to the 3A, -> 3 T, 3A, -> 3T, (F) and 3A2„ -> 3T,„(P) transitions, 2g 2g i 2g l g v ' ^ < s ' e v '
respectively, indicating the octahedral geometry with A ground
state. Copper(II) complexes exhibit two distinct bands centred in the
18300-18800 and 15650-16300 cm"1 regions assignable to 2B, -> 2E
and 2 B, -> 2 B, transitions respectively which is characteristic of an 1 g 2g r J
octahedral geometry.
The magnetic moments obtained from the manganese(II).
cobalt(II), nickel(II) and copper(II) complexes also are entirely
consistent with six-coordination at the metal centres.
References 1 [ 971
REFERENCES
E. Kimura, T. Yatsunami, A. Watanaba, R. Michida, T. Koike, H. Fujioka, Y. Kuramoto, M. Sumomogi, K. Kunimitsu and A. Yamashita, Biochim. Biophys. Acta., 1983, 37, 745.
M.C. Shen, Q.H. Lou, S.R. Zhu, Q.Y. Tu, A.D. Liu, H.C. Gu, F.M. Li and S.J. Di, Chem. J. Chinese Univ. Ser., B, 1990, 6, 354.
R.S. Drago, B.B. Cordon and C.W. Barnes, J. Am. Chem. Soc, 1986, 08, 2453.
M. Shakir and S.P. Varkey. Polyhedron 1995, 14, 1117.
M. Shakir, O.S.M. Nasman, A.K. Mohamed and S.P. Varkey, Polyhedron 1996, 15, 2869.
M. Shakir and S.P. Varkey, Transition Met. Chem., 1994, 19, 606.
E. Kimura, J. Coord. Chem., 1986, 1, 15; E. Kimura, Pure Appl. Chem., 1986, 58, 1461.
M. Kodama and E. Kimura, J. Chem. Soc. Dalton Trans., 1979, 1783.
M. Shionoya, E. Kimura and Y. Litaka, J. Am. Chem. Soc, 1990, 112, 237.
X.H. Bu, D C . An, Y.T. Chem. M. Shionoya and E. Kimura, J. Chem. Soc. Dalton Trans., 1995, 2289.
M. Kodama and E. Kimura, J. Chem. Soc. Dalton Trans., 1979, 325.
Chapter 3 References i cm
12. M.K. Kim and A.E. Martell, J. Am. Chem. Soc, 1966, 88, 914.
13. A.P. Brunatti, M.C. Lim and G.H. Nancollas, J. Am. Chem. Soc, 1968, 90, 5120.
14. R.P. Agarwal and D.P. Perrin, J. Chem. Soc Daiton Trans., 1977, 53.
15. T. Kaden and A. Zuberbuhler, Helv. Chim. Acta., 1966, 49, 2189.
16. P.A. Temussi and A.Vitagoliano, J. Am. Chem. Soc, 1975, 97, 1572.
17. Y. Suguiro, Inorg. Chem., 1978, 17, 2176.
18. T.A. Khan, S.S. Hassan, S.P. Varkey, M.A. Rather and M. Shakir, Transition Met. Chem., 1996, 21, 1.
19. M. Shakir, S.P. Varkey and T.A. Khan, Indian J. Chem., 1995, 34A, 72.
20. W.J. Geary, Coord. Chem. Rev., 1971, 7, 81.
21. K. Nakamoto, "Infrared Spectra of Inorganic and Coordination Compounds", Wiley Interscience, New York, 1970.
22. P.W. Ball and A.B. Blake, J. Chem. Soc, (A), 1969, 1415.
23. M.C. Jain, A.K. Srivastava and P.C. Jain, Inorg. Chim. Acta., 1977, 23, 199.
24. A.B.P. Lever, "Inorganic Electronic Spectorscopy", Elsevier, Amsterdam, 1984.
25. J. Chem. N. Ye, N.W. Alcock and D.H. Busch, Inorg. Chem.. 1993, 32, 904.
26. M.G.B. Drew, F.S. Esho and S.M. Nelson, J. Chem. Soc. Daiton Trans., 1983. 1653.
Chapter 3 Tetraiminetetraamide Macrocyclic Complexes | | 99
3.3
SYNTHESIS AND SPECTROSCOPIC STUDIES OF TETRAIMINETETRAAMIDE MACROCYCLIC COMPLEXES
3.3.1 INTRODUCTION
The polyamide macrocycles deserve special attention as
in some cases these macrocycles have been used for the construction
of the corresponding polyaza macrocyclic complexes1 . In view of the
continued interest in polyamide macrocycles, various macrocyclic
complexes bearing amide groups have been reported recently2 \ from
different reactions. Schiff-base ligands containing N=C-C=N
structural unit, forming a strong chelate ring have been of great
interest, because of electron dereal iza t ion and conjugation of the
Chapter 3 Tetraiminetetraamide Macrocyclic Complexes 1 | 100|
ligand which may affect the nature of the complex formed4. However,
till date only a few complexes with such ligands have been
reported5"7. We have very recently reported the template synthesis of
various polyamide macrocyclic complexes8"1 and have a long term
interest in producing polyamide macrocyclic complexes of a wide
variety. In this study, we report a new series of tetraiminetetraamide
"7 "7
macrocyclic complexes of the type [ML X2] and [CuL ]X2 [M =
Mn", Co11, Ni" and Zn"; X = CI or N0 3 ] obtained by the template
condensation of l ,2-diphenylethane-l,2-dione dihydrazone
(DPEDDH) and dimethyl or diethyloxalate.
3.3.2 MATERIALS AND METHODS
The chemicals benzil, hydrazinehydrate (Merck),
dimethyl and diethyloxalate (both Fluka) were used as received. The
metal salts MX2 .6H20 (M = Co" or Ni11), MnX2 .4H20, CuX2 .2H20 (X
= CI or N0 3 ) , ZnCl2 and Zn(N0 3) 2 .6H 20 (all BDH) were
commercially pure samples. l,2-Diphenylethane-l,2-dione
dihydrazone (benzildi-hydrazone) was prepared by the reaction of the
benzil and hydrazinehydrate in methanol in 1:2 molar ratio. Benzil
(1.05 gm, 5 mmol) was dissolved in MeOH (75 cm3) and kept
magnetically stirred in a round-bottomed two-necked flask.
Chapter 3 Tetraiminetetraamide Macrocyclic Complexes | | 1011
Hydrazinehydrate (48 cm3, 10 mmol) was added to the stirred
mixture. The resultant mixture was stirred for 8 hrs. The solid
product was filtered off and washed several times with methanol. The
chalky white product thus obtained was dried over fused CaCl :
Dichloro/nitrato(6,7,14,15-tetraoxo-2,3,10,ll-tetraphenyl-l,
4, 5, 8, 9, 12, 13, 16-octaazacyclohexadecane-l, 3, 9, 11-tetraene)
metal(II), |M L7X2] [M = Mn", Co", Ni", and Zn"; X = CI or
N 0 3 ] and (6, 7, 14, 15-tetraoxo-2, 3, 10, 11-tetraphenyl-l, 4, 5, 8,
9, 12, 13, 16-octaazacyclohexadecane-l, 3, 9, l l-tetraene)copper(lI)
chloride/nitrate ICuL7]X2 [X = CI or N 0 3 ] .
A gradual colour change was observed when a sample (1.191
gm, 20 mmol) of l ,2-diphenylethane-l,2-dione dihydrazone
(DPEDDH), suspended in CH2C12 (150 cm3), was treated with a
methanolic (65 cm3) solution of metal salt (10 mmol) and dimethyl
(0.51 cm3, 20 mmol) or diethyloxalate (0.68 cm3, 20 mmol)
simultaneously. The reaction mixture was stirred for 8 hrs. and then
it was refluxed for 13 hrs. The product obtained was filtered off,
washed with CH2CI2 and dried over fused CaCI2 kept in a desiccator.
Chapter 3 Tetraiminetetraamide Macrocyclic Complexes 102
3.3.3 RESULTS AND DISCUSSION
Novel tetraiminetetraamide macrocyclic complexes
[ML7X2] and [CuL7]X2 [M = Mn", Co", Ni11 and Zn11; X = CI or N0 3 ]
have been prepared by the condensation reaction of 1,2-dip-
henylethane-l,2-dione dihydrazone (DPEDDH) with dimethyl or
diethyloxalate followed by metal templation in 2:2:1 molar ratio
(Scheme 8). Both starting materials dimethyl or diethyloxalate were
used with each metal leading to the identical products. The
complexes examined show poor solubility in solvents like,
chloroform, carbon tetrachloride and water. However, they are freely
soluble in dimethylsulphoxide and warm dimethylformamide The
elemental analyses (Table 9) results agree well with the mononuclear
structure. The molar conductivities in DMSO indicate11 '1 that
copper(II) complexes are electrolytic while others are non-
electrolytic in nature.
The IR spectra (Table 10) of all the complexes are similar but
strikingly different from the spectra of free ligand. The spectra of
free ligand (DPEDDH) shows two strong, medium intensity
prominent bands at 3290, 3210cm"!, assignable to v(N-H) vibrations
of amino groups which occur at slightly lower frequencies than are
usually associated with v(N-H) vibrations of
Chapter 3 Tetraiminetetraamide Macrocyclic Complexes 103
Ph Ph
H o o
IHjN—NH ?
Stirring M»OH
H , M - N
> /
Ph
Ph
X N - N H ?
0 0
M RO OR
RtCH3W C j H 5
Ph Ph
- \ | N N ^ O <W ^ N — N N
H Ph Ph
Ph p
O C7
\ / Cu
M Ph Ph
1 ?•
M = Mn", Co", Ni», and Zn" A = CI or N 0 3
Scheme 8
Table 9. % Yield, Colour, Meiting point, Molar Conductance and Analytical Data for the Compounds.
Compound % Y i e l d C o l o u r M e l t i n g Am — P o i n t (Gm2C2_1mol_1) C <°C)
Found ( C a l c . ) %
H N M CI
DPEDDH 61
[MnL 7 (N0 3 ) 2 ] 4 8
[MnL7Cl2 ; 51
[ C o L 7 ( N 0 3 ) 2 ] 53
White
Pink
167
185
Light pink 193
Bright pink 210
21.5
18.6
19.9
70.8 ;70.5)
50.7 !50.3)
54.6 :54.1)
6.0 [5.9!
3.6 ; 3 . 2 )
3.7 : 3 . 4 )
2 4.0 !23.5)
18.7 [18.3)
16.2 ;i5.8)
7.4 (7.2)
8.2 (7.8)
50.3 3.3 18.5 7.2 (50.0) (3.1) (18.2) (7.6)
10.2 ( 9 . 8 :
[CoL Cl2] 48 Light pink 221 17.5 54.2 : 5 3 . s ;
3.0 :3.4;
16.1 15.7)
7.8 !8.2)
10.3 (9.8)
[NiL (N03)2: 51 Green 195 20.5 50.5 :50.i;
3.5 3.1)
18.7 18.2)
7.3 7.5;
[NiL7Cl2] 51 Dim g r e e n 205 2 1 . 0
[CuL 7 ] (N0 3 ) 2 53 Brown 215 107
[CuL7]Cl2 55 Dark brown 221 98
;ZnL7(N03)2] 54 White 190 19 .4
[ZnL7Cl2] 53 O f f - w h i t e 197 18 .7
* D i m e t h l y o x a l a t e was u s e d a s t h e s t a r t i n g m a t e r i a l
DPEDDH = 1, 2 - d i p h e n y l e t h a n e - 1 , 2 - d i o n e d i h y d r a z o n e
54 . 3 ( 5 4 . 0 )
4 9 . 7 ( 4 9 . 2 )
5 3 . 9 ( 5 3 . 4 )
5 0 . 2 ( 4 9 . 7 )
5 3 . 7 ( 5 3 . 4 )
3 . 1 ( 3 . 4 )
3 . 4 ( 3 . 1 )
3 . 0 ( 3 . 3 )
3 . 5 ( 3 . 1 )
3 . 7 ( 3 . 3 )
1 5 . 3 ( 1 5 . 7 )
1 8 . 4 ( 1 8 . 1 )
1 5 . 3 ( 1 5 . 6 )
1 8 . 5 ( 1 8 . 1 )
1 5 . 2 ( 1 5 . 6 )
7 . 7 ( 8 . 1 )
8 . 4 ( 8 . 2 )
7 . 8 ( 8 . 1 )
8 . 5 ( 8 . 9 )
9 . 3 ( 9 . 0 )
9 . 4 ( 9 . 8 )
-
9 . 3 ( 9 . 7 )
-
1 0 . 2 ( 9 . 7 )
Table 10. IR Spectral Data (cm x) for the Compounds.
Compound V(NH2/NH)
I
DPEDDH 3290 ,3210 -
[MnL 7 (N0 3 ) 2 ] 3250 1690
[MnL 7Cl 2] 3270 1680
[ C o L 7 ( N 0 3 ) 2 ] 3275 1 7 1 0
[ C o L 7 C l ? ] 3 2 7 5 1 6 9 5
[ N i L 7 ( N 0 3 ) 2 ] 3 2 6 5 1 7 0 0
[ N i L 7 C l 2 ] 3240 1 7 1 5
[CuL7] ( N 0 3 ) 2 3250 1 6 9 5
[ C u L 7 ] C l 2 3245 1 6 8 0
Amide b a n d s V(C=N)
I I I I I IV
1 6 1 5
1530 1240 650 1 5 9 5
1510 1 2 5 5 670 1580
1520 1 2 4 5 640 1 5 8 0
1 5 2 5 1230 635 1590
1540 1 2 3 5 665 1 5 9 5
1530 1 2 5 0 650 1 5 8 5
1545 1250 670 1580
1550 1 2 4 5 655 1 5 9 0
V(M-N) R i n g v i b r a t i o n s
1 2 4 5 , 1 0 2 5 , 8 7 5
440 1 2 3 0 , 1 0 1 5 , 8 6 0
425 1 2 3 5 , 1 0 1 0 , 8 5 5
460 1 2 4 0 , 1 0 2 5 , 8 6 5
470 1 2 2 5 , 1 0 3 0 , 8 7 0
450 1 2 4 0 , 1 0 2 0 , 8 4 5
435 1 2 3 0 , 1 0 2 5 , 8 6 0
455 1 2 3 5 , 1 0 1 0 , 8 4 0
450 1 2 2 5 , 1 0 0 5 , 8 7 5
[ Z n L ' ( N 0 3 ) 2 ] 3250 1685
[ZnL C l 2 ] 3265 1690
DPEDDH - 1, 2 - d i p h e n y l e t
1535 1230 655 1595
1520 1225 635 1585
a n e - 1 , 2 - d i o n e d i h y d r a z o n e .
450
445
1230,1015,855
1240,1010,850
Table 11. H NMR Spectral Data* for the Compounds.
Compound
DPEDDH
[ZnL7(N03)2]
[ZnL7Cl2]
N-NH-C
.42 (s;
• 45(s)
N-NH2
4.92 (s;
Phenyl ring protons
7.18(m)
6.90(m)
6.97(m)
emical shifts (5/ppm) with multiplicities in parenthesis s ~ singlet and m = multiplet
Table 12. neff Values, Ligand Field Bands observed i
Parameters for the Compounds.
Compound
fMnL7(NOj)2]
[MnL7CI2]
[CoL7(N03)2]
[CoL7Cl2]
[NiL7(NO,)2]
(B.M.)
5.75
5.70
4.65
4.57
3 18
Band position
-u (cm )
18650 22550
18850
22400
16200 21400
15950
21700
18200 24350
in the Electronic Spectra (cm1), their Assignments and EPR Spectral
Assignments
6A,g -* 4T,g(P) 6Aig -> 4T2g(F)
%g - • 4T,g(P) 6A,g -> 4T2g(F)
4T,g(F) -> 4A2g(F) 4T,g(F) - • 4T,g(P)
4T,g(F) -> 4A2g(F) 4T,g(F) -> 4T,g(P)
A2g(F) 3A2g(F)
Tig(F)
'T,g(P)
8|
EPR data
oo
oo o o
fN
fN
Li. 0 . "so "so
t T
"3D 56 < <
» a „ CM — 6 0
CQ < tU fN fS fN
T T T so so so
CQ 03 CO <N fN fN
5 0 M w , fN — SO
co < to fN fN fN
A .*> /f.
i i T so so so
CO CQ CQ fN fN fN
o I T )
r-00 —
o o (N •—• fN
O i n r-— —
o »o o • o —
o o l/~i
~ (N
o vn T (N —
© O © \D —
o 1/-I
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fN
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u
Chapter 3 Tetraiminetetraamide Macrocyclic Complexes | | 111]
primary amino groups7. This result is expected because of the high
degree of conjugation in the ligand as the interaction of amino group
lone pair with conjugated groups weakens the N-H bond. The v(C=N)
vibration band appeared at 1615cm"1, which is found to be slightly
negatively shifted than that usually found for the azomethine linkage,
further confirm the dereal izat ion of electrons in the free ligand.
The most singnificant feature of IR spectra of the complexes is
the appearance of four characteristic13 amide bands in the 1680-1715,
1510-1550, 1225-1255 and 635-670 cm"1 regions. The amide I,
v(C=0), is observed in the region expected for the metal-free amide
group ruling out the possibility of coordination through amide
oxygen. The complexes gave a single sharp v(N-H) band in 3240-
3275 cm'1, region, which is found similar to analogous metal-free
tetraaza ligand14. This indicates that the amide nitrogens do not
involve in coordination.
Reported macrocyclic complexes exhibit a strong intensity band
in the range of 1580-1595 cm"1 assignable13 to the coordinated
v(C=N). There is observed increase in the v(C=N) band intensity
which may be due to the possible transformation of trans-structure of
the free ligand (DPEDDH) into cis configuration upon complexation.
The c/5-structure is stabilized by the chelate ring, lowering the
Chapter 3 | [ Tetraiminetetraamide Macrocyclic Complexes | | 112
symmetry which consequently enhances the v(C=N) band intensity.
The bands at 425-470 cm"1, originate from (M-N) vibration. In
addition, the 1R spectra of nitrato complexes exhibit bands at 1280,
1040 and 850 cm'1 which are consistent with the monodentate
nature16 of this group. However, the phenyl ring vibrations appear at
their expected positions.
The ]H NMR spectra (Table 11) of benzildihydrazone
(DPEDDH) and the corresponding zinc complexes have been
recorded and compared. Benzildihydrazone shows a multiplet at 7.18
ppm and a slightly broad signal at 4.92 ppm assignable to the
phenyl ring (C6H5, 10H) and amino (N-NH2, 4H) protons of the
hydrazone moiety. Both the zinc complexes showed the appearance of
a band at 8.42, 8.45 ppm, reasonably ascribed18 to amide (N-NH-
C,4H) protons. A multiplet at 6.90, 6.97 ppm in both complexes is
characteristic of phenyl ring (C6H5, 20H) protons. Absence of
characteristic peaks corresponding to the protons of hydrazone and
oxalate moieties, further confirm that the cyclization has indeed
taken place.
The room temperature EPR spectra (Table 12) of both
polycrystalline Cu(II) complexes exhibit a similar single broad
absorption band. However, no complex is found to give hyperfine
Chapter 3 Tetraiminetetraamide Macrocyclic Complexes j | 113}
splitting. The calculated gj and gi values appeared in the region
2.31, 2.34 and 2.08, 2.09 respectively, which support the contention
that dx2 /2 may be the ground state of the unpaired electron. Both the
complexes studied show g|| > 2.3, indicating appreciable ionic
character19. The g values are related by the expression G = (g|-2)/
(g±-2) and the present complexes [CuL7]X2 [X = CI or N0 3 ] gave
axial symmetry parameter, G at the 3.875, 3.777 region, indicating
considerable exchange interaction among copper(II) ions in these
complexes, as the G values are less than 4.
The electronic spectra (Table 12) of manganese gave two bands
in the 22400-22550 and 18650-18850 cm"1, regions which may be
assigned to 6 A l g -> 4T2g(F) and 6 A l g -> 4T,g(P) transitions
respectively, corresponding to an octahedral environment around the
Mn11 ion. The cobalt complexes exhibit two ligand field bands in the
21400-21700 and 15950-16200 cm"1, regions which may reasonably
correspond to 4T l g(F) -> 4T l g(P) and 4T,g(F) -» 4A2g(F) transitions,
respectively, consistent with octahedral geometry21 around the Co
ion. All the nickel complexes exhibit two electronic bands in
21200 - 24350 and 18200 - 18750 cm"1, regions which may be
ascribed to 3A2g(F) -> 3T l g(P) and 3A2g(F) -> 3T l g(F) transitions,
respectively, suggesting22 an octahedral coordination around the
Chapter 3 | Tetraiminetetraamide Macrocyclic Complexes 114
metal ion. Magnetic moment values are in close agreement with their
electronic spectral.data which further support the proposed geometry.
The observed magnetic moments of Cu(II) complexes fall in the
range 1.87, 1.92. B.M. The electronic spectra of these complexes
show a broad band maximum at 16050 cm"1 which may be assigned to
B l g -» Aig transition. However, two weak shoulders appearing in the
regions 21500-21750 and 11750-12450 cm"1 may be attributed to 2 B l g
7 7 9 T 1
-> 'Eg and B ] g —> B2g transitions, respectively, suggesting a
square-planar geometry around the Cu11 ion.
References | \ 115[
REFERENCES
M. Shakir and S.P. Varkey, Indian J. Chem., 1995, 34A, 355 and the references therein.
M. Shakir and S.P. Varkey, Polyhedron 1995, 14, 1117.
M. Shakir, O.S.M. Nasman, A.K. Mohamed and S.P. Varkey, Polyhedron 1996, 15, 2869.
S. Padhye and G.B. Kauffman, Coord. Chem. Rev., 1985, 63, 127.
C. Matsumoto and K.S.N.K. Zasshi, Chem. Abstr., 1967, 88, 340; 1967, 67, 58963.
T.W. Bell and A.T. Papoulis, Angew Chem. Int. Edn. Engl, 1992, 31, 749.
A. Arquero, M.A. Mendiola, P. Souza and M.T. Sevella, Polyhedron 1996, 15, 1657.
T.A. Khan, S.S. Hasan, A.K. Mohamed, K.S. Islam and M. Shakir, Synth. React. Inorg. Met.- Org. Chem., 1997(Accepted).
T.A. Khan, S.S. Hasan, S.P.Varkey, M.A. Rather, N. Jahan and M. Shakir, Transition Met. Chem., 1997, 22, 4.
T.A. Khan, M.A. Rather, N. Jahan, S.P. Varkey and M. Shakir, Transition Met. Chem., 1997 (in press).
W.J. Geary, Coord. Chem. Rev., 1971, 7,82.
M. Shakir, S.P. Varkey and P.S. Hameed, Polyhedron 1994, 13, 1355.
M. Shakir and S.P. Varkey, Polyhedron 1995, 14, 1117.
D.H. Cook and D.E. Fenton, Inorg. Chim. Acta., 1977, 25, L95.
Chapter 3 References 116
15. J. Nelson, B.P. Murphy, M.G.B. Drew, P.C. Yates and S.M. Nelson, J. Chem. Soc. Dalton Trans., 1988, 1001.
16. P.W. Ball and A.B. Blake, J. Chem. Soc, (A), 1969, 1415.
17. M. Shakir, A K. Mohamed, S.P. Varkey, O.S.M. Nasman and Z.A. Siddiqi, Polyhedron 1995, 14, 1277.
18. D. Parker, K. Pulukkody, F.C. Smith, A. Batsanov and J.A.K. Howard, J. Chem. Soc. Dalton Trans., 1994, 689.
19. I S . Ahuja and S. Tripathi, Indian J. Chem., 1991, 30A, 1060.
20. I.M. Proctor, B.J. Hathway and P. Nicholls, J. Chem. Soc, (A), 1968, 1678.
21. A.B.P. Lever, "Inorganic Electronic Spectroscopy", Elsevier, Amsterdam (1984).
22. E. Kimura, J. Coord. Chem., 1986, 15, 1.
23. M. Shakir, S.P. Varkey and P.S. Hameed, Polyhedron 1993, 12, 2775.
Chapter 3 Bis(macrocyclic) Complexes | | 117[
3.4
SYNTHESIS AND CHARACTERIZATION OF BIS(MACROCYCLIC) COMPLEXES
3.4.1 INTRODUCTION
Recently, a series of investigations has reported the
introduction of macrocyclic ligands which are able to encapsulate
two metal i o n s ' 2 . Many researchers have prepared numerous
binuclear macrocyclic complexes where one of the metal sites
exhibits coordinative saturation and the other metal is in a
coordinatively unsaturated site 4. Such complexes largely have been
employed for the study of the redox behaviour accompanying
dioxygen binding to metals. The isolation of bis(macrocyclic)
Chapter 3 | | Bis(macrocyclic) Complexes | | 118
nitrogen donor ligands with binuclear coordination sites for transition
metals has attracted much interest and a variety of systems have been
reported5"9 Fenton10 has reviewed this class of compounds
emphasizing their relevance to bioinorganic model systems. Recent
studies on bimetallic bis(cyclam) compounds reveal that many such
compounds can be used as electrocatalysts for the reduction " of
0 2 , C 0 2 or H 2 0 and it was proven that bis(cyclams) containing two
metals are better electrocatalysts than those of the corresponding
mononuclear species. Several articles have been reported in recent
years on the coordination chemistry of bis(macrocyclic) molecules in
which two potentially coordinating tetraaza subunits are linked
together by bridging amine nitrogen or carbon atoms of the ligand's
backbone14"17. In such compounds each tetraaza unit may coordinate a
metal ion and the two metal centres may display independent or
interdependent behaviour based on the length of the bridge joining
the two subunits. This study deals with the synthesis and
characterization of a new series of bis(macrocyclic) complexes
bridged with a benzidine moiety and in this study we are interested
in generating the more unusual situation where the two macrocyclic
rings are far from each other and in which the two encapsulated metal
centres can act as independently as possible.
Chapter 3 Bis(macrocyclic) Complexes
3.4.2 MATERIALS AND METHODS
The metal salts, benzidine and formaldehyde were obtained
from E. Merk & Co. Tnethylenetetraamine was obtained from
Aldrich Chemicals.
Dichloro/nitrato[ 1,1-phenyl bis(3,6,9,12-tetrahydro-l,3,6,
Q II
9,12 - pentaazacyclotrldecane))metal(II), IM2L X4] [M = Mn ,
Co", Ni", Cu11 and Zn11 ; X = CI or N0 3 J.
To a stirred methanol (25 cm3) solution of benzidine (0.920
gm, 5 mmol) and 35% aqueous formaldehyde (2 cm3, 20 mmol)
in a two-necked round-bottomed flask was added a methanol (50 cm )
solution of the metal salt (10 mmol) and triethylenetetraamine (0.98
cm3, 10 mmol) simultaneously. The resulting mixture was stirred for
about 7 hrs. and the solid product thus obtained was filtered, washed
with methanol and vaccum dried.
3.4.3 RESULTS AND DISCUSSION
A new series of bis(macrocyclic) complexes, [M2L X4] [M
= Mn11, Co", Ni", Cu" and Zn11; X = CI or N03] have been
synthesized by the template reaction of benzidine, formaldehyde and
triethylenetetraamine in 1:4:2 molar ratio (Scheme 9). All complexes
Chapter 3 Bis(macrocyclic) Complexes | 1 120]
are stable to the atmosphere and are polycrystalline in nature.
Elemental analyses (Table 13) agree well with the bis(macrocyclic)
complexes formulated as shown in Scheme 9. The molar conductance
values in DMSO are supportive of the non-electrolytic nature of all
complexes18.
The important IR spectral results are presented in Table 14. In
all the complexes, a single sharp band observed around 3210 cm"
may be assigned19 to v(N-H) of the coordinated secondary amino
groups. Along with these results, the most important feature is that
the IR spectra of the complexes gave no bands assignable to primary
amino or carbonyl group stretching modes. These data are consistent
with the suggested structure. The bands corresponding to phenyl
group vibrations appear at their expected positions
(Table 14). The IR spectra of all the complexes gave bands around
1170 cm"1 which may be assigned to the v(C-N) vibration. All the
complexes show absorption bands around 2910 and 1450 cm"
corresponding to v (C-H) and 8(C-H) vibrations, respectively. The
chloro complexes display a medium intensity band in the 310-
330 cm region which may be attributable to an M-Cl stretching
vibration. Furthermore, the appearance of a medium intensity band
Bis(macrocyclic) Complexes
H,N NH2 / HCHO
+
1 H2N N H NH 2
H V X / H H \ x / "
M = M n " , C o " , Ni" , C u " and Z n " X = CI or N 0 3
Scheme 9
Table 13. % yield, Colour, Melting point, Molar Conductance and Analytical Data for the Compounds.
Compound % Yield Colour Melting Am Point (cm^'mor1)
(°C)
Found (Calc.)%
H N M CI
[Mn2L8(NO04] 68 Iron grey
[Mn2L8Cl4]
[Co2L8Cl4]
[Ni2L8(NOi)4]
65 Yew green
[Co2L8(NO,)4] 71 Dark brown
62 Off grey
59 Frost grey
310
317
192
239
317
13.0
12.5
13.5
12.5
15.0
37.7 (38.1)
42.8 (43.3)
38.2 (37.7)
43.0 (42.8)
38.1 (37.8)
5.5 (5.4)
6.7 (6.2)
5.2 (5.4)
5.8 (6.1)
5.3 (5.4)
22.7 (22.2)
17.5 (18.0)
21.7 (22.0)
18.3 (17.9)
21.6 (22.0)
11.9 (12.4)
13.5 18.7 (14.0) (18.2)
13.7 (13.2)
13.7 17.5 (14.0) (18.0)
12.7 (13.0)
[Ni2L8Cl4] 58 Castor grey 315 11.5
[Cu2L8(NO.0.,J 75 Slag 327 13.5
[Cu2L*Cl4] 74 Dim green 198 17.5
[Zn2L8(N03)4] 64 Colourless 316 15.5
[Zn2L8CL] 61 Dirty white 191 17.5
42.5 5.7 18.4 15.1 17.8 (42.8) (6.1) (17.9) (14.8) (18.0)
36.9 5.8 22.1 13.8 (37.3) (5.3) (21.7) (14.0)
41.8 5.5 17.5 16.4 18.3 (42.3) (6.0) (17.1) (16.0) (17.8)
36.7 5.6 22.2 13.9 (37.2) (5.3) (21.7) (14.4)
41.6 5.7 18.1 16.6 18.1 (42.1) (6.0) (17.6) (16.2) (17.7)
Table 14 . IR S p e c t r a l Data (cm 1) f o r t h e Compounds.
8
Compound V(N-H) v(C-H) v(C-N) v(M-N) 8(C-H) V(M-Cl) NO3 group vibrations Ring vibrations
[Mn2L (N03)4] 3220 2910 1180 470 1450 - 1060,1300 1410,1030,720
[Mn2L Cl4] 3200 2900 1170 440 1440 310 - - 1430,1050,760
[Co2L (N03)4] 3210 2920 1170 440 1450 - 1050,1300 1410,1060,740
p
[Co2L Cl4] 3210 2890 1170 440 1460 330 - - 1420,1020,780
p
[Ni 2 L (N0 3 ) 4 J 3220 2 9 1 0 1160 430 1 4 4 0 - 1 0 6 0 , 1 2 6 0 1 4 4 0 , 1 0 4 0 , 7 3 0
p
[Ni 2 L C l 4 ] 3210 2 9 0 0 1170 450 1440 310 - - 1 4 2 0 , 1 0 4 0 , 7 3 0
p
[Cu2L (N03)4] 3220 2920 1180 450 1450 - 1060,1290 1440,1060,780
o IT )
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Table 15 . XH NMR S p e c t r a l Data* f o r the Compounds.
Compound N-CH2-N N-CH2-C C-NH-C N- C6H4"N
[Zn2L (N03)4] 3.34(m) 2.43(m) 6.38(m) / .23(m)
[Zn2L8Cl4] 3.36(m) 2.46(m) 6.41(m) 7.28(m)
* C h e m i c a l s h i f t s m "-- mul t i p ] e t
(5 /ppm) w i t h m u l t i p l i c i t i e s i n p a r e n t h e s i s
Table 16. \ieff Values, Ligand Field Bands observed in the Electronic Spectra (cm" ), their Assignments and EPR Spectral Parameters for the Compounds.
Compound n Band position Assignments
(B.M.) (cm"1) g | gj_
[Mn2L*(NO,)4] 5.83 18600 22400
[Mn2L*Cl4] 5.85 18900 22600
[Co2Lg(NO,)4] 4.27 13900
21500
[Co2LKCl4] 4.13 14300
21900
[Ni2L8(NO,)4] 3.11 11200
20000
27500
6A,g -» % g ->
6A,g -> 6A,g ->
4T,g (F) -> 4T,g(F) ->
4T,g(F) - • 4T,g(F) ->
3A2g(F) - • 'A2g(F) -> 3A2g(F) ->
4T,g(P) 4T2g(F)
4T,g(P) 4T2g(F)
4A2g(F) 4T,g(P)
4A2g(F) 4T,g(P)
3T2g 'T,g(F)
3T,g(P)
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Chapter 3 Bis(macrocyclic) Complexes ] uE
in the region 430-470 cm'1 which is assignable to a v(M-N) vibration
further confirm the involvement of the nitrogen in coordination. In
addition to these vibrational bands, two more bands have been
observed in the spectra of the nitrato complexes at around 1060 and
1300 cm ' which may be assigned to the assymmetric and symmetric
stretches vi and v2 of the nitrate group. We conclude that the NO3
group is coordinated in a unidentate manner based on these data and
10
in comparison with similarly bound nitrate groups .
!H NMR spectra (Table 15) of bis(macrocyclic) zinc complexes
recorded in DMSO- d6 show two multiplets in 6.38, 6.41 and 3.34,
3.36 ppm regions which correspond21 22 to the secondary amino (C-
NH-C,8H) and methylene (N-CH2-N,8H) protons, respectively.
Another multiplet observed for both the complexes in the 2.43, 2.46
ppm region may be due to the methylene (N-CH2-C,24H) protons of
the triethylenetetraamine moiety. Another multiplet observed for all
the compounds in the region 7.23 and 7.28 ppm corresponds to the
aromatic ring protons23 and the relative intensity for the biphenyl
protons is expected to show 1:1 ratio. More interestingly, no band is
observed which is assignable to the aldehydic or primary amino
protons which strongly support the concluded ligand frame-work.
Chapter 3 Bis(macrocyclic) Complexes ] [M
The room temperature EPR spectra (Table 16) of the copper(II)
bis(macrocyclic) complexes show a single broad band with two g
values at 2.25. 2.30 and 2.09. 2.14 Gauss, respectively. The absence
of hyperfine splitting signals in these complexes may be due to strong
dipolar and exchange interactions between the copper(II) ions in the
unit cell24. The observed g values indicate25 the presence of an
unpaired electron in the d., , orbital, a phenomenon reported in
many other complexes. The ratio G = (g||-2)/ (gi-2) implies the
possibility of exchange interaction in the copper complexes . When
G > 4. the exchange interaction is negligible and vice versa. In the
present complexes, the value is 2.142 and 2.777 which indicates a
considerable exchange interaction present in these complexes. It has
been reported27 that g|| is a sensitive function for indicating
covalency; for an ionic environment, gp is greater than 2.3 and for a
covalent environment gj is less than 2.3. In the present complexes,
gU < 2.3, is indicative of the covalent nature of the complexes.
The electronic spectra (Table 16) of the manganese complexes
gave two bands in the regions 18600,18900 and 22400,22600 cm"1
which may be assigned28 to 6A l g -> 4T l g(P) and 6A l g -> 4T2g(F)
transitions, respectively, suggesting an octahedral environment
around the manganese(II) ion. However, the spectra of the cobalt
Chapter 3 Bis(macrocyclic) Complexes ] DE
complexes gave two ligand field bands in the regions 13900,14300
and 21500,21900 cm'1 which are assigned to the 4T, , (F) - • 4A3f(F)
and 4Tig(F) -> 4T l g(P) transitions, respectively, consistent with the
octahedral geometry of the cobalt ion. The expected band below
11100 cm"1 could not be recorded as it is beyond the range of the
instrument used. The broad band in the range 11200,11350 cm" and
the two distinct bands in the spectra of the nickel complexes in the
20000,20600 and 27500,27850 cm"1 regions may be attributable
to the 3A2g(F) -> 3T2 g , 3A2g(F) - • 3T l g(F) and 3A2g(F) -+ 3T l g(P)
transitions, respectively. The electonic spectra of the copper
complexes exhibit two bands in the regions 16300,16500 and
19900,20400 cm"1 which unambig-uously may be assigned to the
: B l g -> 2B2 g and 2 B ! g -> 2Eg transitions, respectively, corresponding
to a distorted octahedral geometry of the copper ion. The magnetic
moment values further suggest the proposed geometry. All the
complexes exhibit a high-intensity band around 35000 cm" which
may be due to the charge transfer transition (either metal to ligand,
or ligand to metal). The electronic absorption bands of all the
bis(macrocyclic) binuclear complexes, in comparison with those of
the similar mononuclear complexes reported earlier, do not show
appreciable differences. Furthermore, the magnetic moment values of
Chapter 3 Bis(macrocyclic) Complexes 132
the present complexes agree well with their mononuclear analogues.
This similarity in spectral and magnetic properties suggest that the
metal centres are non-interacting in the present complexes in
solution. However, intermolecular interaction cannot be ruled out in
the solid complexes.
3 References ] run
REFERENCES
S.V. Rosokha, Y D . Lampeka and L.M. Maloshtan, J. Chem. Soc. Daiton Trans., 1993.631.
A. Bilyk and M M . Harding, ./. Chem. Soc. Daiton Trans., 1994, 77.
C. Fraser. R. Ostrander. A.L. Rheingold, C. White and B. Bosnish, Inorg. Chem., 1994, 33, 324.
D.G. McCollum, L. Hall, C. White, R. Ostrander, A. L. Rheingold, J. Whelan and B. Bosnich, Inorg. Chem., 1994, 33, 924.
M. Shakir, S.P. Varkey and O.S.M. Nasman, Polyhedron 1995, 14, 1283.
V.B. Arion, N.V. Gerbelen, V.G. Levitsky, Y. A. Simonov, A. A. Dvorkin and P.N. Bourosh, J. Chem. Soc. Daiton Trans., 1994, 1913.
H.S. Mountford. D.B. MacQueen, A.L. J.W. Otros, M. Calvin, R.B. Frankel and L.O. Spreer, Inorg. Chem., 1994, 33, 1748.
M. Shakir, S.P. Varkey and P.S. Hameed, Polyhedron, 1995, 14, 1355.
M. Shakir and S.P. Varkey, Transition Met. Chem., 1994, 39, 606.
D.E. Fenton, Adv. Inorg. Bioinorg. Mech., 1983, 21, 817.
J.P. Collin, A. Jonaiti and J.P. Sauvage, Inorg. Chem., 1988, 27, 1988.
J.P. Collman, N.H. Hendricks, C. R. Leidener, E. Nagmeni and M.Liter, Inorg. Chem., 1988, 27. 387.
M. Baley, J.P. Collin, R. Ruppert and J.P. Sauvage. J. Am. Chem. Soc, 1986, 108, 7461.
14. L. Fabbrizzi, F. Forlini, A. Perotti and B. Seghi, Inorg. Chem., 1984, 23, 807.
15 E.K. Barefield. D. Chueng, D.G. V. Derveer and F.J. Wagner, J. Chem. Soc Chem. Commun., 1981, 302.
16. A. Buttafare. L. Fabbrizzi, A. Perotti, A. Poggi and B. Seghi, Inorg. Chem., 1984, 23, 3917.
17. M. Cianpolini, M. Micheloni, N. Nardi, F. Vizza, A. Buttafare, L. Fabbrizzi and A. Perotti, J. Chem. Soc. Chem. Commun., 1984, 998.
18. W. J. Geary, Coord. Chem. Rev., 1971, 7, 81 .
19. M. Shakir and S.P. Varkey, Polyhedron 1995, 14, 1117.
20. P.W. Ball and A.B. Blake, J. Chem. Soc, (A), 1969, 1415.
21. M. Shakir, S. P. Varkey and P.S. Hameed, J. Chem. Research (M), 1993, 11 ,2969.
22. K. Burgers, D. Lim, K. Kantto and C.Y. Ke, J. Org. Chem., 1995, 59, 2179.
23. M. Shakir and S.P. Varkey, Polyhedron 1 9 9 4 , 1 3 , 9 4 1 .
24. l.S. Ahuja and S. Tripathi, Indain J. Chem., 1991, 30A,1060.
25. B.J. Hathaway and A.A.G. Tomlinson, Coord. Chem. Rev., 1970, 5, 1.
26. I.M. Proctor. B.J. Hathaway and P. Nicholls, J. Chem. Soc, A, 1968, 1678
27. D Kivelson and R. R. Neiman, J. Chem. Phys., 1961, 35,149.
28. A.B.P. Lever. "Inorganic Electronic Spectorscopy", Elsevier, Amsterdam (1984).
Chapter 3 Dithiadiaza Macrocyclic Complexes J [ 135
3.5
SYNTHESIS AND SPECTROSCOPIC STUDIES OF DITHIADIAZA MACROCYCLIC COMPLEXES
3.5.1 INTRODUCTION
The chemistry of macrocyclic compounds is a rapidly
developing research area in view of their various applications' ~,
particularly in the field of catalysis3 4. The metal ion chemistry of
macrocyclic compounds incorporating sulfur and nitrogen or sulfur,
nitrogen and oxygen as donor sites in the ring system have been
studied extensively5"11, but investigation of the effects of
incorporating a soft sulfur donor into a ligand frame-work containing
Chapter 3 Dithiadiaza Macrocyclic Complexes | [ 136|
harder nitrogen atom is of great interest6"12'13. Although sulfides are
generally treated as very poor ligands to transition metal centres ,
recent studies15"17 have proved that macrocyclic sulfides readily bind
to transition metal ions to form stable complexes. It has been noted
that addition of appropriate ring substituents should assist in the pre-
organization of the ligand towards an endo conformation in which the
1 R
lone pairs on the sulfurs are oriented towards the ligand cavity ,
resulting in increased stability constant. In this laboratory, for quite
sometime, we have been engaged in a program aimed at credible
synthesis of macrocyclic complexes10 containing sulfur and nitrogen
donor atoms and in this study we wish to report a new series of
dithiadiaza macrocyclic complexes obtained by the template
condensation of 1, 2-ethanedithiol, o-bromoaniline and succinic or
phthalic acid.
3.5.2 MATERIALS AND METHODS
The chemicals o-bromoaniline, 1,2-ethanedithiol (both
Fluka Chemika), succinic acid (Loba Chemie, India), phthalic acid
(S.D. Fine Chemicals, India) were used as received. The metal salts
MX2.6H20 [M = Co" and Ni"; X = CI or N03), CuX2.2H20 [X = CI
Chapter 3 Dithiadiaza Macrocyclic Complexes [ [ 137|
or NO3], Zn(N0.02 and ZnCl2 were BDH quality, available
commercially.
Dichloro/nitrato(l:2,7:8-dibenzo- 10,13- dioxo-3,6-dithia-
9,14-diazacyclotetradecane)metal(II), [ML9X2] [M = Co" or Zn";
X = CI or N0 3 ] and (l:2,7:8-dibenzo-10,13-dioxo-3,6-dithia-9,14-
diazacyclotetradecane)metal(II) chloride/nitrate [ML9]X2 [M =
Ni H or Cu n ; X = CI or NO3].
A mixture of o-bromoaniline (3.44 gm, 20 mmol) and 1,2-
ethanedithiol (0.84 cm3, 10 mmol) in methanol (75 cm3) was taken in
a round bottomed flask and stirred with slight heating for about 35
min. A warm methanolic (50 cm3) solution of the metal salt (10
mmol) was added dropwise followed by the addition of succinic acid
(1.18 gm, 10 mmol) dissolved in MeOH (30 cm3). A brisk colour
change was observed after the addition of metal salt solution. The
resulting mixture was stirred again for 13 hrs. The solid product thus
separated was filtered off, washed several times with methanol then
with ether and dried in vacuo.
Dichloro/nitrato(l:2,7:8,ll:12-tribenzo-10,13-dioxo-3,6-
dithia-9,14-diazacyclotetradecane)metal(II), [ML , 0X2] [M = Co11
or Zn"; X = CI or NO3I and (1:2, 7:8,11:12-tribenzo 10,13 -dioxo-
Chapter 3 Dithiadiaza Macrocyclic Complexes 138
3,6-dithia-9,14-diazacyclotetradecane)metal(II) chloride /nitrate
[M L10] X2 [M = Ni" or Cu11; X = CI or N 0 3 ] .
To a stirred mixture of o-bromoaniline (3.44 gm, 20 mmol) and
1,2-ethanedithiol (0.84 cm3, 10 mmol) in methanol (75 cm3 ) was
added dropwise a warm methanolic (50 cm3 ) solution of metal salt
(10 mmol). This was followed by the addition of phthalic acid (1.66
gm, 10 mmol) dissolved in methanol (30 cm3). A gradual colour
change was observed. The reaction mixture was kept stirring for 13
hrs. and the solid mass was isolated by filtration, washed several
times with methanol and dried in desiccator.
3.5.3 RESULTS AND DISCUSSION
A new series of dithiadiaza transition metal complexes have
been prepared via the condensation reaction of 1,2-
ethanedithiol, o-bromoaniline and succinic or phthalic acid in the
presence of transition metal ions as templates (Scheme 10). Attempts
to prepare metal free ligands in methanol led to oily product, which
could not be isolated and analysed. However, when the condensation
reaction was carried out in the presence of metal ions, solid products
were obtained in good yield (65-85%). The complexes prepared by
Chapter 3 Dithiadiaza Macrocyclic Complexes 139
\ / ^ N H +
^
M X 2
fa ™ ^
SH SH
OH HO
o s s
X H N |NH
1' " S
L , n = (CH2)2 ; m L10, n = (CH2)2 ; m M = C o u and Z n n
X = CI or N 0 3
(CH2)2
C6H4
L% n = (CH2)2; m L10, n = (CH2)2; m M = Ni n and C u n
(CH2)2
C6H4
Scheme 10
Table 17. % Yield, Colour, Melting point, Molar Conductance and Analytical Data for the Compounds.
Compound % Yield Colour Melting Am Point (cm ft mol ) C <°C)
Found (Calc.)%
H N M CI
[CoL (N03)2] 67 Dark brown 310 21 39. 7 39.9)
3.0 3.3)
10.7 10.3!
10.7 10.9)
12.2 (11.8)
[coi/ci2 : 74 bright brown 319 19 4 4 . 7 4 . 0 5 . 9 1 2 . 5 1 4 . 6 1 3 . 6 4 4 . 3 ) ( 3 . 6 ) ( 5 . 7 ) ( 1 2 . 1 ) ( 1 4 . 3 ) ( 1 3 . 1 1
10 CoL ( N 0 3 ) 2 ] 65
[CoL 1 0 Cl 2 ] 71
Bright brown 309
Blackish brown 327
16 4 5 . 1 ; 4 4 . s :
3 . 3 3 . 0 !
9 . 9 4 . 5 )
9 . 7 ( 1 0 . 0 )
11 . 2 1 0 . 8 '
4 9 . 6 3 . 4 5 . 6 1 1 . 2 1 4 . 2 1 1 . 3 ( 4 9 . 2 ) ( 3 . 3 ) ( 5 . 2 ) ( 1 0 . 9 ) ( 1 3 . 9 ) ( 1 1 . 8 )
[ N i l / ] ( N 0 3 ) 2 65 Blackish brown 312 104 40.2 3.7 10.5 10.4 (39.8) (3.2) (10.2) (10.8;
12.3 (11.9:
[NiL/]Cl2
10
67
[NiL ] (N03)2 72
Dark brown 322
Bright brown 307
98
114
44.7 3.5 6.1 (44.3) (3.7) (5.6)
45.2 ,44.8:
3.3 . 3 . 0 :
9.8 9 . 5 :
12.3 13.8 13.4 (12.0) (14.2) (13.0)
9.6 : 9 . 9 i
11.2 (10.8)
[ N i L 1 0 ] C l 2 76
[CuL9] ( N 0 3 ) 2 79
[ C u L 9 ] C l 2 81
[CuL 1 0 ] (No 3 ) 2 84
[ C u L l 0 ] C l 2 85
[ Z n L 9 ( N 0 3 ) 2 ] 65
[ZnL 9 Cl 2 ] 79
[ Z n L 1 0 ( N O 3 ) 2 ] 75
[ Z n L 1 0 C l 2 ] 68
Dark brown 321
Dim green 323
Dark green 239
Light brown 241
Blackish brown 263
Dim blue 314
Greyish blue 319
Dim blue 325
Bright blue 337
49.6 3.5 (49.2) (3.3)
40.1 3.6 (39.9) (3.2)
44.2 3.2 (43.9) (3.6)
42.7 3.4 (42.2) (3.0)
49.2 3.7 (48.8) (3.3)
39.7 3.0 (39.4) (3.2)
44.2 3.3 (43.8) (3.6)
44.6 3.3 (44.3) (3.0)
48.9 3.5 (48.6) (3.3)
5.5 11.3 (5.2) (10.9)
10.6 11.2 (10.2) (11.6)
5.8 12.7 (5.6) (12.9)
9.7 10.3 (9.4) (10.5)
5.6 12.0 (5.1) (11.7)
10.6 11.4 (10.2) (11.8)
5.6 13.6 (5.2) (13.2)
9.7 11.3 (9.4) (10.9)
5.5 12.4 (5.1) (12.0)
13.6 12.3 (13.2) (11.9)
11.5 (11.7)
14.5 13.3 (14.2) (13.0)
10.3 (10.6)
13.5 11.5 (13.1) (11.8)
12.1 (11.7)
14.5 13.3 (14.1) (12.9)
11.2 (10.7)
13.4 11.4 (13.0) (11.7)
Table 18. IR Spec t ra l Data (cm" ) f o r t h e Compounds.
Compound V(C-H)
I
[CoL 9 (N0 3 ] 2 ]
[CoL 9 Cl 2 ]
[ C o L 1 0 ( N 0 3 ) 2 ]
[CoL 1 0 Cl 2 ]
[ N i L 9 ] ( N 0 3 ) 2
[ N i L 9 ] C l 2
[ N i L 1 0 ] ( N 0 3 ) 2
t N i L 1 0 ] C l 2
[CuL 9 ] ( N 0 3 ) 2
2955
2945
2940
2920
2 8 9 5
2910
2 9 0 5
2920
2 9 3 0
1710
1690
1700
1 7 2 5
1 7 0 5
1 7 1 5
1710
1 7 2 0
1 6 8 5
Amide bands V(M-N)
II I£I IV
1535 1265 650 395
152 0 12 60 655 415
1530 1255 665 420
1520 1260 660 400
1510 1240 645 395
1520 1230 635 400
1530 1235 640 405
1505 1225 650 410
1535 1230 640 395
V(M-S) V(M-C1) Ring vibrations
340 - 1400,1020,720
355 280 1405,1015,725
360 - 1415,1025,735
370 275 1420,1035,740
365 - 1410,1030,730
370 - 1430,1050,720
355 - 1400,1020,750
340 - 1425,1025,735
345 - 1425,1035,740
I D CM
r o n o .—i
o oo M-
o CM
r-o CM
o 1—1
i n C\J
r
IT) L O
r o «a* o 1—1
o o ^T
i n oo r-o r
o i—i
m oo • ^
U0 00
r-o ^T
o I—1
O
oo V
IT) CM
r-m oo o • — 1
m 0 0 <3"
o 0 0
r-U0 CM
o 1—1
o oo *y
c CM
in oo CM
o <=r oo
Ln oo oo
o <X> oo
o T on
c 0", oo
o m n
m T oo
o <3<
m i—i
m o r-H * T
m o T
o o ^
m ^r IX>
oo 00 IX>
o LO \D
m T <X>
O 00 <£>
O
• <X>
m oo >X>
m oo CM
m CM CM
m iX>
CM
m £>
CM
LT,
r-CM
m m CM
O r-CM
o oo m
m i—i
m
m 00 m
o r\j m
oo o 00
o 1—1
m
m tn VX>
o CT^. IX)
o T—1
r-
o CM r~
o in 00 CM
o CM Cft (M
m i—i
CTi CM
m m en CM
o CM
cn CM
OO CM C^, CM
o o CTi CM
o 1—1
(T\ CM
I N
H
u '—' O l
^ 3 U
o 2
. — i
o i - i
^ 3 U
eg .—1
u o ~H
^ 3 u
.—. n
O 2 ~— a-, J C
M
, rg
CJ
o\ .J C N)
m O 2
o , — i
^ C
N]
• H t )
o ,—1
h3 C
Nl
Table 19. 1H NMR S p e c t r a l Data* f o r t h e Compounds
Compound C-NH-CO CO-CH2-CH2-CO S - CH2-C Phenyl r i n g
[ZnL9(N03)2] 8.43(m) 3 . 2 9 ( s ) 3.76(m) 7 .33(m)
[ZnL9 Cl 2 ] 8.36(ra) 3 . 3 3 ( s ) 3.81(m) 7.24(m)
[ZnL10(NO3}2] 8.32 (m) - 3 .78 (m) 7 . 2 1 (m)
[ZnL1 0Cl2] 8.37(m) - 3.87(m) 7.31(m)
^Chemical shifts (5/ppm) with multiplicities in parenthesis s = singlet and m = multiplet
Table 20. \ie{f Values, Ligand Field Bands observed in the Electronic Spectra (cm1), their Assignments and EPR Spectral
Parameters for the Compounds.
Compound K-ff. (B.M.)
Band position
(cm1)
Assignments
g|
EPR data
[CoL9(N03)2]
[CoLTI2]
[CoL,0(NO3)2]
[CoL,0Cl2]
[NiL9](N03)2
[NiL;] Cl2
4.09
4.10
4.08
4.10
16900
21800
16400
21500
16950 21850
16450 21650
16200
20700
15850 19550
g(F g(F
g(F
g(F
g(F g(F
g(F g(F
Aig
Aig
Aig Aig
-> A2g(F)
- • 4Tig(P)
-> A2g(F)
-> 4T|g(P)
-> 4A2g(F)
-> 4T.g(P)
-> 4A2g(F)
-» 4Tig(P)
. 1, B,g A2g
-> 'Big
(N r-<N
r<-i 00 o
I T i l / " j
l/">
1 -T • ^
<N
(N
(N O (N
o ( S
(N (N rsi <N
00 J?
T T oo oo < _ <
00
_CQ
T 00
_<
oo <
t oo <
00 00 — 00 rM
< UJ CQ c>l rN (N
t ! t oo oo oo
CQ CQ CQ <N rsi I N
00 00 — 00 <N
< UJ CQ (N IS IN
t T t oo oo oo
CQ CQ CQ (N fS (N
00 00 — OO <N
< UJ CQ fN rs| fN
t t T oo oo oo
CQ CQ CQ d (N N
oo _„ oo - 50 N
< UJ CQ rJ rsi fN
! I
oo oo oo CQ CQ CQ
IN (N fN
o o o 00 o (N
o o o IT)
o w, >o o
c o (N \ 0
o v/-, r-~
o o I/-)
o o —
o \T\
o o o TT
o v> c->
O o oo
o V i l/~>
o V~>
^-o o r
o ir> rr
oo 00 oc
o z o z o z
-J z
- J 3 3
o -J 3
u
Chapter 3 | [ Dithiadiaza Macrocyclic Complexes 147
the template method have 1:1 metal to ligand stoichiometry. The
molar conductance values (Table 17) of cobalt and zinc complexes
indicate that they are non-electrolytic in nature while other
complexes exhibit19 20 their ionic nature. The overall geometries were
inferred from the various spectroscopic studies discussed below.
The preliminary identification of the synthesized macrocyclic
complexes have been obtained from IR spectra. The main bands and
their assignments are listed in the Table 18. The absence of bands
characteristic of thiol or hydroxyl groups and the appearance of
bands corresponding to an amide group strongly suggests that the
proposed ligand frame-work is formed. The four amide bands
identified in the 1685-1730, 1505-1535, 1225-1275 and 630-665 cm"1
regions may reasonably, be assigned to amide I[v(C=0)], II [v(C-N)
+ S(N-H)], amide III [6(N-H)] and amide IV [<KC=0)] bands,
respectively5. The position of amide I, [v(C=0)] band is in the region
of metal free amide"1 which rules out the possibility of coordination
through amide oxygen. The presence of a sharp band in the region
395-420 cm"1 in all the complexes is due to the v(M-N) vibration22.
Bands in the region 275-290 cm"1 are asssignable to v(M-Cl)
stretching vibrations. A new medium intensity band in the region
330-370 cm"1 may reasonably be assigned to v(M-S). The phenyl ring
Chapter 3 Dithiadiaza Macrocyclic Complexes | | 148|
and other fundamental vibrations23 appeared at their expected
positions.
The ]H NMR spectra (Table 19) of zinc(II) complexes recorded
in DMSO- d6 show two broad signals in the region 8.32-8.43 ppm
which may be assigned to the amide (C-NH-CO,2H) protons24 '25. A
singlet in the region 3.29, 3.33 ppm was observed for the respective
complexes [ZnL9(N03)2] and [ZnL9Cl2], which can be assigned26 to
[CO-(CH2)2 - CO,4H] protons. All the zinc complexes show multiplet
in the region 7.21-7.33 ppm owing to phenyl ring protons21. The 'H
NMR spectra of [ZnL9(N03)2], [ZnL9Cl2], [ZnL10(NO3)2] and
[ZnL Cl2], gave a multiplet in the region 3.76-3.87 ppm
corresponding25 to methylene protons adjacent to sulfur (S-CH2,4H).
However, the absence of thiol or carboxylic protons again further
confirm the proposed frame-work.
The EPR spectra (Table 20) of the polycrystalline samples of
copper(II) complexes were recorded at room temperature and their gj
, gi values have been calculated. The copper(II) hyper-fine line could
not be resolved in any of the complexes at room temperature. This
may be attributed to the strong dipolar and exchange interactions
between copper(II) ions in the unit cell27. A single broad signal with
two g values, consistent with an axial symmetry (g | > g±) in the
Chapter 3 Dithiadiaza Macrocyclic Complexes 149
molecule, was exihibited. This indicates28 essentially a d , ground
state for the copper(II) ion. All the macrocyclic copper(II) complexes
gave g|| and gj. values in the 2.32-2.37 and 2.09-2.12 range,
respectively. In these complexes gj > 2.3 is indicative of ionic
nature and is well suited for electrolytic nature of copper. In the
axial symmetry the exchange interaction measurements between the
copper centres in the crystalline solids are expressed by Q = (g | . 2)
/(g± - 2). The calculated G values for the complexes appeared in the
range 3.083 to 3.555 which suggest (G < 4)29 a considerable exchange
interaction in these complexes.
The electronic spectra (Table 20) of the complexes derived
from the cobalt(II) showed two bands aroundl6450 and 21650 cm"1
which may reasonably correspond to the 4T l g(F) -» 4A2g(F) and
Tig(F) -> 4T l g(P) transitions, respectively, suggesting an octahedral
geometry for the complexes30. However, the reflectance spectra of the
cobalt complexes exhibited only one band around 15560 cm"1
assigned to the 4A2g(F) -> 4T,g(P) transition, consitent with the
tetrahedral environment of the macrocyclic moiety around the
cobalt(II) species31. The difference in electronic and reflectance
spectral data suggest that there exist different geometries in solution
and solid state.
Chapter 3 Dithiadiaza Macrocyclic Complexes
The macrocyclic complexes of nickel(II) exhibit two bands in
their electronic spectra at around 15900 and 19650 and may be
assigned to !Aig -> 'Big and 'A] g -> 'A^g transitions, respectively,
suggesting a square-planar geometry around the nickel(II) ion.
The electronic spectra of copper(II) complexes showed a broad
band centred at ca. 16200 assignable to B ] g —> A ]g transitions.
However, two weak shoulders appearing around 21700 and
11450 cm"1 may be ascribed to 2B]g -» 2Eg and 2 B ] g ->
'B 2 g transitions, corresponding to a square-planar geometry around
the copper(II) ions.
The magnetic moment values further confirm the above
proposed geometries.
Chapter 3 References ] tm
3.5.4 REFERENCES
1. D.H. Bush and N.W. Alcock, Chem. Rev., 1994, 94, 585.
2. A.M. Caminade and J.P. Majoral, Chem. Rev., 1994, 94, 1183.
3. J.L. Grant, K. Goswani, L.O. Spreer, J.W. Otvos and M. Calvin, J. Chem. Soc. Dallon Trans., 1987, 2105.
4. G.M. Brown. B.S. Brunchwig, Creutz, J.F. Endicott andN. Sutin. J. Am. Chem. Soc. 1979, 101, 1298.
5. A.J. Blake, G. Reid and M. Schroder, J. Chem. Soc. Dal ton Trans., 1992. 2987.
6. R. Cammack, Adv. Inorg. Chem., 1988, 32, 297.
7. K.E. Krakowiak, J.S. Bradshaw and D.J. Zameckak-rakowiak, Chem. Rev., 1989, 89, 929.
8. K.R. Adam. M. Antolovich, D.S. Baldwin, L.G. Brigden, P.A. Duckworth, L.F. Lindoy, A. Bashall, M. Mcpartlin and P.A. Tasker. J. Chem. Soc. Dalton Trans., 19)2, 1869.
9. K.R. Adam. M Antolovich, D.S. Baldwin, P A . Duckworth. A.J. Leong, L.F. Lindoy, M. Mcpartlin and P.A Tasker. J. Chem. Soc. Dalton Trans., 1993. 1013.
10. M. Shakir. S.P. Varkey and P.S. Hameed, J. Chem. Res., 1993. 11, 442.
11. M. Shakir and S.P. Varkey, Polyhedron 1994. 5, 791.
12. J.I. Bruce, T.M. Donlevy, L.R. Gahan, C.H.L. Kennard and K.A. Byriel, Polyhedron 1996, 15, 49.
13. S.R. Copper, Ace. Chem. Res., 1988. 21, 141.
Chapter 3 C References am
14. S.G. Murray and F.R. Hartley, Chem. Rev., 1981, 81, 365.
15. G. Reid and M. Schroder, Chem. Soc. Rev., 1990, 19, 239.
16. Y. Gok, Polyhedron 1996, 15, 1355.
17. I. Rombero, G.S. Castello, F. Teixidor, C.R. Whitaker, J. Rius and C. Miravitlles, Polyhedron 1996, 15, 2057.
18. J.M.Desper and S.H. Gellman, J. Am. Chem. Soc, 1990, 112, 6732.
19. M. Shakir, S.P. Varkey and P.S Hameed, Polyhedron 1994, 13, 1355.
20. W.J. Geary. Coord. Chem. Rev., 1971, 7, 82.
21. M. Shakir and S.P. Varkey, Transition Met. Chem., 1994. 19, 606.
22. V.B. Rana. P. Singh and M.P. Teotia, Polyhedron 1982, 1, 377.
23. M. Shakir. D. Kumar and S.P. Varkey, Polyhedron 1992, 11, 2831.
24. K. Burgess. D Lim, K. Kantto and C.Y. Ke, J. Org. Chem., 1994. 59, 2179.
25. R.M. Silverstein, G.C. Bassler and T.C. Morrill, "Specirometric Identification of Organic Compounds". 4th Edn. John Wiley and Sons, New York (1981).
26. P.A. Duckworth, L.F. Lindoy, M. Mcpartlin and P.A. Tasker, Aust. J. Chem., 1993, 46, 1787.
27. I.S. Ahuja and S. Tripathi, Indian J. Chem., 1991, 30A, 1060.
References | | 153
M.C. Jain, A.K. Srivastava and P.C Jain, Inorg. Chim. Acta., 1977, 23, 199.
B.J. Hathaway and D.E. Billing, Coord. Chem. Rev., 1970, 5, 143.
A.B.P. Lever, "Inorganic Electronic Specloscopy", Elsevier, Amsterdam (1984).
G. Devoto. M. Massaccsi and G. Ponticelli, J. Inorg. Nucl. Chem.. 1977, 39, 271.
CHAPTER-This chapter concludes the formation, bonding and stereochemistry of newly synthesized complexes.
Chapter 4 1 1 Conclusion | | 15S|
CONCLUSION
r I ^his thesis is a small addition to the coordination
-*- chemistry of transition metal complexes with
multidentate ligands. The main aim behind this study was to
design new macrocyclic ligands and their complexes in view of
their variety of applications. However, an attempt has also been
made to synthesize tin-transition metal heterobimetallic
complexes with a view to provide different environments in the
bimetallic complexes for the metal atoms; one transition (Mn",
Co , Ni", Cu" and Zn") and other non-transition metal have
Chapter 4 Conclusion 156
been choosen for this purpose. The mode of coordination behaviour
of central metal ion is proposed on the basis of available consistent
spectroscopic and physico-chemical data. This project does not
include the various applications, although the synthesis and
characterization of a variety of macrocyclic and heterobimetallic
complexes particularly tetraoxotetraamide, tetraiminetetraamide, bis-
macrocyclic, dithiadiaza and tin-transition metal heterobimetallic
complexes was based on their applications.
The metal templation was the main criterion adopted to
synthesize these complexes. Except in one case, the medium of
reaction was methanol. The attempts to synthesize metal-free
macrocyclic ligands was futile leading to the formation of unstable
oily product, which could not be isolated and analysed. It is an
established fact that templation is an efficient approach to synthesize
macrocyclic complexes with considerable yields without any side
reactions as compared to high dilution technique, which is used to
synthesize complexes from pre-formed ligands. It is, therefore,
concluded that metal ion directs the steric course of the reaction in
the synthesis of macrocyclic complexes to provide better yields.
The complexes obtained were stable to atmosphere in the solid
state and were freely soluble in polar solvents like
Chapter 4 | | Conclusion | | 157
dimethylformamide, dimethylsulphoxide and acetonitrile. The molar
conductance values in DMSO were generally supportive of their non-
electrolytic nature, however, in certain cases complexes of nickel and
copper exhibit their ionic behaviour. The results of spectroscopic
studies, viz. IR, 'H NMR, EPR, electronic spectral and magnetic
susceptibility measurements show that the complexes in general have
octahedral stereochemistries except a few complexes of nickel and
copper which exhibit square-plannar geometries.