organometallic nickel(ii) complexes with dithiophosphate, dithiophosphonate and monothiophosphonate...

Inorganica Chimica Acta 357 (2004) 677–683

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Organometallic nickel(II) complexes with dithiophosphate,dithiophosphonate and monothiophosphonate ligands

Gregorio S�anchez a, Joaqu�ın Garc�ıa a, David J. Meseguer a, Jos�e L. Serrano b,Jos�e P�erez b, El�ıes Molins c, Gregorio L�opez a,*

a Departamento de Qu�ımica Inorg�anica, Universidad de Murcia, 30071 Murcia, Spainb Departamento de Ingenier�ıa Minera, Geol�ogica y Cartogr�afica (Area de Qu�ımica Inorg�anica),

Universidad Polit�ecnica de Cartagena, 30230 Cartagena, Spainc Institut de Ci�encia de Materials, CSIC, Camps Universitari de Bellaterra, 08193 Cerdanyola, Spain

Received 9 April 2003; accepted 11 June 2003

Abstract

The hydroxo complex [NBu4]2[Ni2(C6F5)4(l-OH)2] reacts with ammonium O;O0-dialkyldithiophosphates, O-alkyl-p-methoxy-

phenyldithiophosphonate acids and ammonium O-alkylferrocenyldithiophosphonates in dichloromethane under mild conditions

to give, respectively, [NBu4][Ni(C6F5)2{S(S)P(OR)2}] (R¼Me (1), Et (2), iPr (3)) and [NBu4][Ni(C6F5)2{S(S)P(OR)Ar}] (Ar¼ p-

MeOC6H4, R¼Me (4), Et (5), iPr (6); Ar¼ ferrocenyl; R¼Me (7), Et (8), iPr (9)). The monothiophosphonate nickel complexes

[NBu4][Ni(C6F5)2{S(S)P(OR)(ferrocenyl)}] (R¼Et (10), iPr (11)) are obtained by reaction of the hydroxo complex with

O-alkylferrocenyldithiophosphonate acids. Analytical (C, H, N, S), conductivity, and spectroscopic (IR, 1H, 19F and 31P NMR, and

FAB-MS) data were used for structural assignments. A single-crystal X-ray diffraction study of [NBu4][Ni(C6F5)2{S(S)P(OMe)(p-

MeOC6H4)}] (4) and [NBu4][Ni(C6F5)2{S(O)P(OEt)(ferrocenyl)}] (10) shows that in both cases the coordination around the nickel

atom es essentially square planar with NiC2S2 and NiC2SO central cores, respectively.

� 2003 Elsevier B.V. All rights reserved.

Keywords: Nickel complexes; Dithiophosphate complexes; Dithiophosphonate complexes; Monothiophosphonate complexes

1. Introduction

Phosphor-1,1-dithiolate-type ligands, which include

the monoanionic dithiophosphates, dithiophosphinates,

and dithiophosphonates (Scheme 1 (a)–(c)), have re-

ceived continuous attention, since they display a wide

variety of coordination modes which leads to a diversity

of molecular and supramolecular structures [1–3]. Fur-

thermore, their metal complexes have been effectively

used as additives in lubrication oils [4–6], and the solu-bility in organic solvents of many metal derivatives has

allowed to develop extraction procedures [7]. Some of

the organometallic derivatives have been found to dis-

play antitumor activity [8] and others are useful in ag-

riculture as insecticides [9]. The synthesis and

application of dithiophosphinate complexes of nickel as

* Corresponding authors. Fax: +34-968-364148.

E-mail address: [email protected] (G. L�opez).

0020-1693/$ - see front matter � 2003 Elsevier B.V. All rights reserved.

doi:10.1016/j.ica.2003.06.013

catalyst precursors for the oligomerization of ethylene

has also been recently reported [10].In contrast to the well documented chemistry of

transition metal complexes with dithiophosphates (a)

and dithiophosphinates (b) [1–3,10,11], synthetic diffi-

culties have prevented a wider use of dithiophospho-

nates (c) as ligands [12,13]. The utilization of the

Lawesson�s reagent [ArP(S)S]2 (Ar¼ p-MeOC6H4) [14]

and the related ferrocenyl dimer (Ar¼ ferrocenyl)

to generate dithiophosphonic acids by reaction with

Scheme 1.

mail to: [email protected]

678 G. S�anchez et al. / Inorganica Chimica Acta 357 (2004) 677–683

alcohols and sylanols [15] under appropriate conditions

pointed out a new route to obtain dithiophosphonate

complexes. Thus, the corresponding ammonium salts,

readily obtained from the acids through reaction with dry

NH3, enabled the preparation of some gold(I) [15] andplatinum(II) derivatives [16]. The ring-opening of the

Lawesson�s reagent was also the key step to prepare ho-

moleptic dithiophosphonate and amidodithiophospho-

nate complexes of nickel, palladium and platinum [17]. In

any case, a nucleophilic agent is required to induce the

ring-opening of the [ArP(S)S]2 dimers. Up till now,

methanol, that acts both as solvent and reagent, and

amines in an inert solvent are the alternatives to achievedirect reaction with a few metallic precursors [17]. The

previous isolation of the sodium or the above mentioned

ammonium salts, followed by reaction with a convenient

precursor, completes the available routes to synthesise

ditiophosphonate complexes, that for the time being have

not allowed the preparation of organometallic nickel(II)

complexes with di- and monothiophosphonate ligands.

On the other hand, the dinuclear bis(l-hydroxo)complex [Ni2(C6F5)4(l-OH)2]

2� has shown to be an use-

ful and versatile reagent for the preparation of a wide

variety of complexes, on the basis of the considerable

nucleophilicity of their bridging OH groups. Thus,

compounds of the types [Ni2(C6F5)4(l-X)2]2� or

[Ni(C6F5)2X]� (X¼ exo- or endo-bidentate ligands) have

been obtained by reaction of this precursor with the cor-

responding protic electrophile, HX or (NH4)X, respec-tively (X¼ azoles [18], thiols [19], aromatic alcohols [20],

heterocycle-2-thiones [21], anionic N-donor ligands [22]

and thiometallates [23]). In a related reaction, the hy-

droxo complex reacts with primary and secondary amines

in the presence of carbon disulfide to give dithiocarba-

mate complexes [24]. Recently, we have also prepared

some mononuclear organometallic complexes of nick-

el(II) with thiolate and dithiocarbamate ligands [25] aswell as some dithiophosphate and dithiophosphonate

complexes of pentacoordinate nickel(II) [26].

Following our systematic study of the reactivity shown

by hydroxo complexes of the nickel group elements, we

have now investigated the reactions of [Ni2(C6F5)4(l-OH)2]

2� with ammonium O;O0-dialkyldithiophosphates,ammoniumO-alkylferrocenyldithiophosphonates andO-alkylaryldithiophosphonate acids. It has shown to be anovel and interesting synthetic route to obtain the first

organometallic nickel(II) derivatives with these ligands.

2. Experimental

2.1. Materials and physical measurements

All the solvents were dried by conventional methods.

[NBu4]2[Ni2(C6F5)4(l-OH)2] [18], ammonium O;O0-dialkyldithiophosphate [27], O-alkyl-p-methoxypheny-

ldithiophosphonates acids [14] and ammonium O-al-

kylferrocenyldithiophosphonates [15] were prepared as

described elsewhere.

C, H, N and S analyses were carried out with a Carlo

Erba instrument. Conductance measurements were per-formed with a Crison 525 conductimeter (in acetone so-

lution, c � 5� 10�4 M). Decomposition temperatures

were determined with a Reichert microscope. IR spectra

were recorded on a Perkin–Elmer-16F PC FT spectro-

photometer, using Nujol mulls between polyethylene

sheets. NMR data (1H, 19F, 31P) were recorded on a

Bruker-AC-200E or Varian 300 instrument, using CDCl3as solvent and SiMe4, CFCl3 or H3PO4 as reference.

2.2. Preparation of the complexes [NBu4][Ni(C6F5)2{S2P(OR)2}] (1–3)

Ammonium dithiophosphate (0.038 mmol) was added

to a solution of [NBu4]2[Ni2(C6F5)4(l-OH)2] (0.1 g, 0.076

mmol) in dichloromethane (10 ml), and the mixture was

stirred at room temperature for 30 min. It was concen-trated under reduced pressure to ca. 2 ml. The addition of

diethyl ether caused the precipitation of the title com-

plexes which were separated, washed with diethyl ether

and air-dried. The complexes were recrystallized from

dichloromethane–hexane.

[NBu4][Ni(C6F5)2{S2P(OMe)2}] (1) was obtained in

62% yield. Anal. Calc. for C30H42F10NNiO2PS2: C, 45.5;

H, 5.3; N, 1.8; S, 8.1. Found: C, 45.2; H, 5.4; N, 1.9; S,8.3%. M.p. 104 �C. KM 115 S cm2 mol�1. IR (Nujol):

668, 650 (PS str). 1H NMR (CDCl3): 4.0 (d, 6H, OCH3,

JPH ¼ 10:0). 19F NMR (CDCl3): )115.4 (d, 4Fo, Jom ¼31:0), )165.9 (t, 2Fp, Jmp ¼ 19:8), )166.6 (m, 4Fm).

31P

NMR (CDCl3): 95.2 (s).

[NBu4][Ni(C6F5)2{S2P(OEt)2}] (2) was obtained in


H, 5.6; N, 1.7; S, 7.8. Found: C, 46.6; H, 5.8; N, 1.8; S,8.1%.M.p. 103 �C.KM 132 S cm2 mol�1. IR (Nujol): 664,

650 (PS str). 1H NMR (CDCl3): 1.5 (m, 6H, OCH2CH3),

4.4 (m, 4H, OCH2CH3).19F NMR (CDCl3): )115.3 (d,

4Fo, Jom ¼ 31:04),)165.2 (t, 2Fp, Jmp ¼ 19:8),)166.7 (m,

4Fm).31P NMR (CDCl3): 90.6 (s).

[NBu4][Ni(C6F5)2{S2P(OiPr)2}] (3) was obtained in


H, 5.9; N, 1.6; S, 7.6. Found: C, 47.8; H, 5.8; N, 1.8; S,7.8%. M.p. 105 �C. KM 126 S cm2 mol�1. IR (Nujol): 644

(PS str). 1H NMR (CDCl3): 1.4 (m, 12H, OCH(CH3)2),

5.3 (m, 2H, OCH(CH3)2).19F NMR (CDCl3): )115.1 (d,

4Fo, Jom ¼ 29:9),)165.2 (t, 2Fp, Jmp ¼ 20:9, ),)166.6 (m,

4Fm).31P NMR (CDCl3): 87.4 (s).

2.3. Preparation of the complexes [NBu4][Ni(C6F5)2{S2P(C6H4OMe-p)(OR)}] (4–6)

5 ml of aliphatic alcohol (ROH) were placed in a flask

with 0.031 g (0.076 mmol) of 2,4-bis(p-methoxyphenyl)-

G. S�anchez et al. / Inorganica Chimica Acta 357 (2004) 677–683 679

1,3-dithiaphosphetane disulfide [Lawesson�s reagent:

(ArP(S)S)2 (Ar¼ p-MeOC6H4)], and the mixture was

boiled under reflux for 30 min. It was concentrated

under reduced pressure to ca. 2 ml and a solution of

[NBu4]2[Ni2(C6F5)4(l-OH)2] (0.1 g, 0.076 mmol) in di-chloromethane (10 ml) was then added. The solution

was stirred at room temperature for 30 min and after

that time was concentrated under reduced pressure to

ca. 2 ml. The addition of diethyl ether (15 ml) and

subsequent cooling to )18 �C for 24 h caused the crys-

tallization of the complex. The compounds were filtered

off, washed with diethyl ether and recrystallized from

dichloromethane–hexane.[NBu4][Ni(C6F5)2{S2P(C6H4OMe-p)(OMe)}] (4) was

obtained in 57% yield. Anal. Calc. for

C36H46F10NNiO2PS2: C, 49.8; H, 5.3; N, 1.6; S, 7.4.

Found: C, 50.0; H, 5.4; N, 1.8; S, 7.5%. M.p. 104 �C. KM

138 S cm2 mol�1. IR (Nujol): 660, 632 (PS str). 1H

NMR (CDCl3): 3.8 (s, 3H, p-MeOC6H4), 4.0 (d, 3H,

OCH3, JPH ¼ 14:84), 6.9 (m, 2H, p-MeOC6H4), 8.1 (dd,

2H, p-MeOC6H4, JPH ¼ 13:6; JHH ¼ 8:8). 19F NMR(CDCl3): )114.6 (br, 2Fo), )115.3 (br, 2Fo), )165.3 (t,

2Fp, Jmp ¼ 19:8), )166.7 (m, 4Fm).31P NMR (CDCl3):

97.0 (s).

[NBu4][Ni(C6F5)2{S2P(C6H4OMe-p)(OEt)}] (5) was

obtained in 54% yield. Anal. Calc. for

C37H48F10NNiO2PS2: C, 50.3; H, 5.5; N, 1.6; S, 7.3.

Found: C, 50.2; H, 5.7; N, 1.8; S, 7.5%. M.p. 112 �C. KM

120 S cm2 mol�1. IR (Nujol): 668, 632 (PS str). 1HNMR (CDCl3): 1.39 (sh, 3H, OEt), 3.8 (s, 3H, p-MeOC6H4), 4.55 (d, 2H, OEt), 6.9 (m, 2H, p-MeOC6H4), 7.93 (m, 2H, p-MeOC6H4).

19F NMR

(CDCl3): )114.9 (br, 2Fo), )115.5 (br, 2Fo), )165.4 (t,

2Fp, Jmp ¼ 19:8, ), )166.7 (m, 4Fm).31P NMR (CDCl3):

93.2 (s).

[NBu4][Ni(C6F5)2{S2P(C6H4OMe-p)(OiPr)}] (6) was

obtained in 61% yield. Anal. Calc. forC38H50F10NNiO2PS2: C, 50.9; H, 5.6; N, 1.6; S, 7.1.

Found: C, 50.7; H, 5.4; N, 1.8; S, 7.3%. M.p. 122 �C. KM

138 S cm2 mol�1. IR (Nujol): 662, 624 (PS str). 1H

NMR (CDCl3): 1.4 (d, 6H, OCH(CH3)2, J ¼ 7:6), 3.8 (s,3H, p-MeOC6H4), 5.4 (m, 1H, OCH(CH3)2), 6.9 (d, 2H,

p-MeOC6H4, JHH ¼ 8:7), 8.2 (dd, 2H, p-MeOC6H4,

JPH ¼ 13:5, JHH ¼ 8:7). 19F NMR (CDCl3): )114.3 (br,

2Fo), )115.1 (br, 2Fo), )165.3 (t, 2Fp, Jmp ¼ 20:6),)166.5 (m, 4Fm).

31P NMR (CDCl3): 90.4 (s).

2.4. Preparation of the complexes [NBu4][Ni(C6F5)2{S(S)P(C5H4FeC5H5)(OR)}] (7–9)

Ammonium alkylferrocenyldithiophosphonate,

[NH4] [S(S)P(C5H4FeC5H5)(OR)] (R¼Me, Et, iPr),

(0.152 mmol) was added to a solution of[NBu4]2[Ni2(C6F5)4(l-OH)2] (0.1 g, 0.076 mmol) in di-

chloromethane (10 ml). The solution was stirred at room

temperature for 15 min. and then concentrated under

reduced pressure to ca. 2 ml. Diethyl ether was added to

precipitate an orange solid, which was filtered off and

recrystallized from dichloromethane–hexane.

[NBu4][Ni(C6F5)2{S(S)P(C5H4FeC5H5)(OMe)}] (7)

was obtained in 62% yield. Anal. Calc. forC39H48F10FeNNiOPS2: C, 49.5; H, 5.1; N, 1.5; S, 6.8.

Found: C, 49.7; H, 5.4; N, 1.7; S, 6.6%. M.p. 124 �C. KM

121 S cm2 mol�1. IR (Nujol): 648 (PS str). 1H NMR

(CDCl3): 4.02 (d, 3H, OCH3, JPH ¼ 15:0), 4.38 (br, 2H,

C5H4-P), 4.47 (s, 5H, C5H5), 4.73 (br, 2H, C5H4-P).19F

NMR (CDCl3): )114.5 (br, 4Fo), )165.2 (t, 2Fp,

Jmp ¼ 19:7), )166.5 (br, 4Fm).31P NMR (CDCl3): 104.8

(s).[NBu4][Ni(C6F5)2{S(S)P(C5H4FeC5H5)(OEt)}] (8)

was obtained in 58% yield. Anal. Calc. for

C40H50F10FeNNiOPS2: C, 50.0; H, 5.2; N, 1.5; S, 6.7.

Found: C, 49.9; H, 5.5; N, 1.6; S, 6.9%. M.p. 128 �C. KM


(CDCl3): 1.40 (sh, 3H, CH3), 4.38 (br, 2H, C5H4-P),

4.43–4.56 (m, 7H, C5H5 +CH2O), 4.75 (br, 2H, C5H4-

P). 19F NMR (CDCl3): )114.5 (br, 4Fo), )165.3 (t, 2Fp,Jmp ¼ 19:5), )166.5 (m, 4Fm).

31P NMR (CDCl3): 100.7

(s).

[NBu4][Ni(C6F5)2{S(S)P(C5H4FeC5H5)(OiPr)}] (9)


C41H52F10FeNNiOPS2: C, 50.5; H, 5.4; N, 1.4; S, 6.6.

Found: C, 50.2; H, 5.5; N, 1.3; S, 6.8%. M.p. 132 �C. KM


(CDCl3): 1.43 (sh, 6H, iPr), 4.38 (m, 7H, C5H4-P+C5H5), 4.78 (br, 2H, C5H4-P), 5.46 (m, 1H, iPr). 19F

NMR (CDCl3): )114.5 (d, 4Fo, Jom ¼ 24:8), )165.4 (t,

2Fp, Jmp ¼ 19:8), )166.6 (m, 4Fm).31P NMR (CDCl3):

96.6 (s).

2.5. Preparation of the complexes [NBu4][Ni(C6F5)2{S(O)P(C5H4FeC5H5)(OR)}] (10, 11)

5 ml of aliphatic alcohol (ROH) were placed in a flask

with 0.043 g (0.076 mmol) of 2,4-bis(ferrocenyl)-1,3-

dithiaphosphetane disulfide and the mixture was then

boiled under reflux for 30 min. It was concentrated

under reduced pressure to ca. 2 ml and a solution of

[NBu4]2[Ni2(C6F5)4(l-OH)2] (0.1 g, 0.076 mmol) in di-

chloromethane (10 ml) was then added. The solution

was stirred at room temperature for 24 h and after thattime concentrated under reduced pressure to ca. 2 ml.

The addition of diethyl ether (15 ml) caused the pre-

cipitation of the complexes, that were filtered off, wa-

shed with diethyl ether and air-dried. The complexes

were recrystallized from dichloromethane–hexane.

[NBu4][Ni(C6F5)2{S(O)P(C5H4FeC5H5)(OEt)}] (10)


C40H49F10FeNNiO2PS: C, 50.9; H, 5.2; N, 1.5; S; 3.4.Found: C, 51.1; H, 5.4; N, 1.8; S, 3.6%. M.p. 133 �C. KM


(CDCl3): 1.36 (sh, 3H, CH3), 4.26 (br, 2H, C5H4-P),

Scheme 2.


4.49 (m, 7H, C5H5 +CH2O), 4.56 (br, 2H, C5H4P).19F

NMR (CDCl3): )114.8 (d, 2Fo, Jom ¼ 27:1), )116.4 (d,

2Fo, Jom ¼ 32:2), )164.4 (t, 1Fp, Jmp ¼ 20:6), )165.3 (t,

1Fp, Jmp ¼ 20:9), )166.5 (m, 4Fm), ), )167.3 (m, 4Fm).31P NMR (CDCl3): 81.6 (s).

[NBu4][Ni(C6F5)2{S(O)P(C5H4FeC5H5)(OiPr)}] (11)


C41H52F10FeNNiO2PS: C, 51.4; H, 5.5; N, 1.5; S, 3.3.

Found: C, 51.2; H, 5.7; N, 1.6; S, 3.5%. M.p. 139 �C. KM


(CDCl3): 1.37 (sh, 6H, iPr), 4.25 (br, 2H, C5H4-P ), 4.46-

4.57 (m, 7H, C5H5 +C5H4-P), 5.54 (m, 1H, iPr). 19F

NMR (CDCl3): )114.5 (d, 2Fo, Jom ¼ 27:9), )116.1 (d,2Fo, Jom ¼ 28:2), )164.6 (t, 1Fp, Jmp ¼ 19:8, ), )165.3 (t,1Fp, Jmp ¼ 19:8), )166.4 (m, 4Fm), ), )167.2 (m, 4Fm).31P NMR (CDCl3): 80.5 (s).

2.6. Crystal-structure determination of complexes 4 and

10

Crystals of 4 (0.40� 0.30� 0.20 mm) and 10(0.40� 0.40� 0.10 mm) suitable for X-ray diffraction

studies were grown from dichloromethane–hexane,

mounted on glass fibre and transferred to the diffrac-

tometer (Siemens P4 for 4 and Enraf-Nonius CAD4 for

10). The crystallographic data are summarised in Table

1. Mo-Ka radiation was used (k ¼ 0:71073 �A); the scan

method was x� 2h corresponding to hmax ¼ 25 (in 4)

and hmax ¼ 23:7 (in 10). Absorption correction was notnecessary in 4; empirical psi-scan absorption correction

Table 1

Crystal data and parameter of data collection for complexes 4 and 10

4

Empirical formula C36H46F10NNiO2PS

Formula weight 868.54

Temperature (K) 173(2)

Absorption coefficient (cm�1) 7.06

Crystal system monoclinic

Space group P21=ca (�A) 11.3270(10)

b (�A) 19.3170(10)

c (�A) 18.7940(10)

b (�) 102.636(4)

Z; V (�A3) 4; 4012.6(5)

Calculated density (g cm�3) 1.438

F(000) 1800

Measured reflections 17 320

No. of independent reflections 7066

Observed reflections 4377

Parameters 478

R1a 0.0406

wR2b 0.1064

Sc 0.649

Maximum, minimum 0.425, )0.314Dq (e �A�3)

aR1 ¼P

kFoj � jFck=P

jFoj for reflections with I > 2rI.bwR2 ¼ f

P½wðF 2

o � F 2c Þ

2�=P

½wðF 2o Þ

2�g1=2 for all reflections; w�1 ¼ r2ðF 2Þ þthe program.

c S ¼ fP

½wðF 2o � F 2

c Þ2�=ðn� pÞg1=2; n is the number of reflections and p th

was made in 10 (Tmin ¼ 0:6938 and Tmax ¼ 0:8286). Thestructures were solved by direct methods (for 4) and by

Patterson method (for 10) SHELXSSHELXS-97 [28] and refined

anisotropically on F 2 (program SHELXLSHELXL-97 [28]). Hy-

drogen atoms were included using a riding model [1].

3. Results and discussion

3.1. Dithiophosphate complexes

The addition of the corresponding ammonium O;O0-dialkyldithiophosphate to a solution of [NBu4]2[Ni2(C6F5)4(l-OH)2] in dichloromethane results in the

rapid formation of bis(pentafluoropheny)-O;O0-dial-kyldithiophosphatenickelate(II) complexes 1–3 shown in

Scheme 2. The complexes are isolated as tetrabutylam-

10

2 C40H50F10FeNNiO2PS

944.40

293(2)

9.32

monoclinic

P21=n11.0320(10)

20.484(2)

19.889(2)

105.575(9)

4; 4329.5(7)

1.449

1952

6674

6322

1927

514

0.0581

0.1058

0.749

0.437, )0.320

ðaPÞ2 þ bP , where P ¼ ð2F 2c þ F 2

o Þ=3 and a and b are constants set by

e total number of parameters refined.


monium salts, and they behave as 1:1 electrolytes in

acetone solutions [29]. The IR spectra of these com-

pounds show the characteristic absorptions of the C6F5

group at ca. 1630 m, 1490 vs., 1050 vs. and 950 vs. cm�1.

The presence of two bands in the 800–780 cm�1 regionfor the so-called ‘‘X-sensitive’’ mode of the C6F5 ligand

is characteristic of the cis-Ni(C6F5)2 fragment [30],

which obviously appears in compounds containing

bidentate chelate ligands. The most relevant IR bands

attributed to the coordinated dithiophosphate ligands

appear in the 1050–960 and 690–630 cm�1 regions [31].

The 1H NMR spectra show the expected aliphatic

signals, and the 19F NMR spectra exhibit the threesignals pattern (4Fo:2Fp:4Fm) usually found in com-

pounds with two equivalent and freely rotating C6F5

groups. The 31P NMR spectra show a single resonance

for the coordinated dithiophosphate ligand at the usual

range. A displacement of the signals downfield as the

aliphatic substituent become smaller is the only re-

markable feature. It has been claimed that the variation

of the S–P–S bond angle affects the 31P chemical shifts,in the sense that resonances downfield correspond to an

increase in this angle [17,32].

3.2. Dithiophosphonate complexes

The 2,4-diaryl-1,3-dithiaphosphetane disulfide dimer

[ArP(S)S]2, (Ar¼ p-C6H4OMe, Lawesson�s reagent)

easily reacts with alcohols (ROH) to form dithiophos-phonic acids, HSP(S)Ar(OR). Slow addition of a

solution of the hydroxo-complex [NBu4]2[Ni2(C6F5)4(l-OH)2] in dichloromethane over the dithiophosphonic

acids in alcohol solution leads to the formation of the

O-alkyl-p-methoxyphenyl-dithiophosphonate complexes

4–6 presented in Scheme 3. On the other hand, the anal-

Scheme 3.

ogous bis(pentafluorophenyl)(O-alkylferrocenyldithio-phosphonate)-nickelate(II) complexes 7–9 were made by

a different synthetic route, that is, treating [NBu4]2[Ni2(C6F5)4(l-OH)2] with 2 equivalents of ammonium

O-alkylferrocenyldithiophosphonate (Scheme 3). All thecomplexes are air-stable orange solids and their acetone

solutions exhibit conductance values corresponding to

1:1 electrolytes [29].

The 1H and 19F NMR data are consistent with the

proposed formulae. The 19F NMR spectra of the new

complexes show three resonances with relative intensi-

ties of 2:1:2, as expected for two equivalent C6F5

groups, while the observed 31P signals follow the trendmentioned above.

The crystal structure of complex 4 has been deter-

mined by single-crystal X-ray diffraction (Fig. 1). Se-

lected geometrical features are given in Table 2. The

overall coordination geometry about the nickel atom is

essentially square planar. The S1–Ni–S2 angle is

slightly restricted by the chelate ring to 87.37(4)� and the

Fig. 1. Structure of the anion of complex 4 in the crystal. Counterca-

tions are Bu4Nþ (not shown).

Table 2

Selected bond lengths (�A) and angles (�) for complexes 4 and 10

4 10

Bond lengths

Ni(1)–C(1) 1.913(3) Ni(1)–C(1) 1.891(8)

Ni(1)–C(7) 1.900(4) Ni(1)–C(7) 1.844(8)

Ni(1)–S(1) 2.2716(10) Ni(1)–S(1) 2.264(2)

Ni(1)–S(2) 2.2712(10) Ni(1)–O(2) 1.997(4)

Bond angles

C(1)–Ni(1)–S(1) 92.90(11) C(1)–Ni(1)–S(1) 175.7(3)

C(7)–Ni(1)–S(1) 176.86(11) C(7)–Ni(1)–S(1) 93.6(2)

C(1)–Ni(1)–C(7) 89.04(15) C(1)–Ni(1)–C(7) 89.9(3)

S(2)–Ni(1)–S(1) 87.37(4) O(2)–Ni(1)–S(1) 81.64(15)

C(1)–Ni(1)–S(2) 179.73(11) C(1)–Ni(1)–O(2) 94.8(3)

C(7)–Ni(1)–S(2) 90.69(11) C(7)–Ni(1)–O(2) 174.7(3)


Ni–C distances are similar to those found in other

pentafluorophenylnickel compounds [19,22,25]. The two

C6F5 rings are planar and rotated from each other by

86.8�. The Ni–S bond lengths (2.2716(10) and 2.2712(10)�A) are longer that those found in the tetracoordinatenickel(II) complexes [Ni{S2P(NHiPr)(C6H4OMe)}2]

(2.216(2), 2.225(2), 2.227(2) and 2.228(2) �A) [17] and

[Ni{S2P(OEt)(C6H4OMe)}2] (2.2197(8) and 2.2225(8)�A) [33] and the hexacoordinate complex [Ni{S2P(OMe)

(C6H4OMe)}2(py)2] (2.504(1) and 2.494(1) �A) [34]. The

P–S distances in 4 (1.997(1) and and 1.991(1) �A) are

similar to those found in related compounds indicating

substantial p delocalization of the negative charge over

the S–P–S fragment.

3.3. Monothiophosphonate complexes

We have found that the reaction of O-al-kylferrocenyldithiophosphonic acids, obtained by means

of the ring opening reaction of the 2,4-diferrocenyl-1,3-

dithiadiphosphetane disulfide dimer with alcohols (eth-

anol and 2-propanol), with the hydroxo complex

[NBu4]2[Ni2(C6F5)4(l-OH)2] in dichloromethane at

room temperature (24 h), gives the O-ethyl or O-isopropyl-ferrocenylmonothiophosphonate nickel com-

plexes 10 and 11 (Scheme 3). The IR spectra of the

complexes show the bands attributed to C6F5 groups

and the corresponding to the thiophosphonate ligands.

The 1H NMR spectra exhibit the resonance signals of

the aliphatic and ferrocenyl protons, and the 19F NMR

data are consistent with the presence of two different

C6F5 groups, one trans to O and one trans to S.The crystal structure of 10 (Fig. 2) consists of anionic

mononuclear nickel complexes and tetrabutyl ammo-

nium cations. The planar coordination around nickel is

Fig. 2. Structure of the anion of complex 10 in the crystal. Counter-

cations are Bu4Nþ (not shown).

sligthly distorted, with a smaller chelate angle S1–Ni–O2

(81.6�) than that found in complex 4. The Ni–C dis-

tances trans to S are close in both complexes but they are

longer than the Ni-C distance (1.844(8 �A) trans to O.

The rotation between the C6F5 rings (88.9�) is similar tothat found in 4, and the angle of the eclipsed cyclo-

pentadienyl rings with the S–P–O chelate plane is 81.1�.The Fe–Ni distance is 5.29 �A. The Ni–O bond length is

1.997(4) �A and the Ni–S bond length of 2.264(2) �A is

slightly shorter than those observed in complex 4. The

P–O (1.547(5) �A) and P–S (1.975(3) �A) bond lengths of

the O–P–S fragment are shorter than the corresponding

ones (1.556 and 2.093 �A, respectively) found in[Ti{OSP(¼ S)(C6H4OMe)}L], L being the tetradentate

ligand 7,16-dihydro-6,8,15,17-tetramethyldibenzo (1,4,

8,11) tetraazacyclotetradecine [35].

4. Supplementary data

Crystallographic data have been deposited with the

Cambridge Crystallographic Data Centre, CCDC No.

196328 (4) and CCDC No.196329 (10), respectively.

Copies of this information may be obtained free ofcharge from the Director, CCDC, 12 Union Road,

Cambridge CB2 1EZ, UK (fax: +44-(0)1223-336033;

e-mail: [email protected]. ac.uk or www: http://www.

ccdc.cam.ac.uk).

Acknowledgements

Financial support of this work by the Direcci�onGeneral de Investigaci�on del Ministerio de Ciencia yTecnolog�ıa (Project No. BQU2001-0979-C02-01/02),

Spain, is acknowledged.

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organometallic nickel(ii) complexes with dithiophosphate, dithiophosphonate and monothiophosphonate...

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