(Phenylthiomethyl)silanes and (butyltelluromethyl)silanes as novel bifunctional ligands for the construction of dithioether-, ditelluroether- and transition metal-silicon complexes

Article abstract of DOI:10.1016/S0020-1693(02)01519-0

The functionalized silanes (PhSCH₂)₂SiPh₂ (1a), (PhSCH₂)₂Si(vinyl)Me (1b), (PhSCH₂) ₂Si(H)Me (1c) and (PhSCH₂)₃SiH (1d) have been prepared and co-ordinated as chelating dithioether ligands or via a covalent M-Si bond to various transition metal centers. Thus, reaction of 1a with [PtCl₂(PhCN)₂] affords the dithioether complex cis-[PtCl₂{(PhSCH₂)₂SiPh₂}] (3), which exist in solution as mixtures of DL- and meso-invertomers. Treatment of [Re(μ-Br)(CO)₃THF]₂ with 1a-c yielded the stereochemically rigid chelate complexes fac-[ReBr(CO)₃{(PhSCH ₂)₂SiR¹R²}] (R¹, R ²=Ph (4a)), (R¹=vinyl, R²=Me (4b)), (R ¹=H, R²=Me (4c)). Due to the presence of two different substituents R¹ and R² on Si, 4b and 4c are isolated as 50:50 mixtures of diastereomers. The presence of a Si-H function in 1c,d can be exploited for Si-H activation reactions. Thus, oxidative addition on [Pt(PPh₃)₂(CH₂=CH₂)] yields the fluxional hydrido silyl complex [Pt(H)(PPh₃)₂{Si(CH ₂SPh)₂Me}] (5a) and the rigid derivative [Pt(H)(PPh ₃)₂{Si(CH₂SPh)₃}] (5b). The ditelluroether complexes cis-[PtCl₂{(RTeCH₂) ₂SiMe₂)] (6a, R=Ph), (6b, R=n-Bu) are obtained by treatment of [PtCl₂(PhCN)₂] with (PhTeCH₂) ₂SiMe₂ (2a) and (n-BuTeCH₂) ₂SiMe₂ (2b), respectively. The complex fac-[ReBr(CO) ₃{(n-BuTeCH₂)₂SiMe₂}] (7) results from the reaction of [Re(μ-Br)(CO)₃THF]₂ with (2b). The new compounds have been studied by multinuclear NMR techniques, the crystal structures of 3, 4a, 5 and 6b have been determined by X-ray diffraction studies.

Full text of DOI:10.1016/S0020-1693(02)01519-0

Inorganica Chimica Acta 350 (2003) 455ꢀ466
/
www.elsevier.com/locate/ica
(Phenylthiomethyl)silanes and (butyltelluromethyl)silanes as novel
bifunctional ligands for the construction of dithioether-,
ditelluroether- and transition metalꢀ
/
silicon complexes
M. Knorr a,*, F. Guyon a, I. Jourdain a, S. Kneifel a, J. Frenzel b, C. Strohmann b,*
a Laboratoire de Chimie des Mate´riaux et Interfaces, Faculte´ des Sciences et des Techniques, Universite´ de Franche-Comte´, 16, Route de Gray,
25030 Besancon Cedex, France
¸
b Institut fur Anorganische Chemie der Universitat Wurzburg, Am Hubland, D-97074 Wurzburg, Germany
¨
¨
¨
¨
Received 10 July 2002; accepted 9 October 2002
Dedicated to Pierre Braunstein.
Abstract
The functionalized silanes (PhSCH2)2SiPh2 (1a), (PhSCH2)2Si(vinyl)Me (1b), (PhSCH2)2Si(H)Me (1c) and (PhSCH2)3SiH (1d)
have been prepared and co-ordinated as chelating dithioether ligands or via a covalent MꢀSi bond to various transition metal
centers. Thus, reaction of 1a with [PtCl2(PhCN)2] affords the dithioether complex cis-[PtCl2{(PhSCH2)2SiPh2}] (3), which exist in
solution as mixtures of DL- and meso-invertomers. Treatment of [Re(m-Br)(CO)3THF]2 with 1aꢀc yielded the stereochemically rigid
chelate complexes fac-[ReBr(CO)3{(PhSCH2)2SiR1R2}] (R1, R2ꢁPh (4a)), (R1ꢁvinyl, R2ꢁMe (4b)), (R1ꢁH, R2ꢁ
Me (4c)). Due
to the presence of two different substituents R1 and R2 on Si, 4b and 4c are isolated as 50:50 mixtures of diastereomers. The presence
of a SiꢀH function in 1c,d can be exploited for SiꢀH activation reactions. Thus, oxidative addition on [Pt(PPh3)2(CH2ꢁCH2)] yields
the fluxional hydrido silyl complex [Pt(H)(PPh3)2{Si(CH2SPh)2Me}] (5a) and the rigid derivative [Pt(H)(PPh3)2{Si(CH2SPh)3}] (5b).
The ditelluroether complexes cis-[PtCl2{(RTeCH2)2SiMe2)] (6a, RꢁPh), (6b, Rꢁn-Bu) are obtained by treatment of
/
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/
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/
/
/
/
/
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[PtCl2(PhCN)2] with (PhTeCH2)2SiMe2 (2a) and (n-BuTeCH2)2SiMe2 (2b), respectively. The complex fac-[ReBr(CO)3{(n-
BuTeCH2)2SiMe2}] (7) results from the reaction of [Re(m-Br)(CO)3THF]2 with (2b). The new compounds have been studied by
multinuclear NMR techniques, the crystal structures of 3, 4a, 5 and 6b have been determined by X-ray diffraction studies.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Silyl complexes; Platinum; Rhenium; Dithioether complexes; Ditelluroether complexes
1. Introduction
successfully used in homogeneous catalysis [1,2]. An-
other recent domain, where dithioether complexes were
investigated are bioinorganic chemistry and biomedical
Thioether ligands SR2 co-ordinated on transition
metal centers are in general easily substituted by other
donor molecules. Incorporation of the thioether func-
tion in a chelating ligand system may significantly
applications [3ꢀ5]. Two possibilities exist to fine-tune
/
the steric and electronic properties of this ligand system:
(i) modification of the SR end groups and/or (ii)
variation of the length and kind of the spacer units
between the two sulfur atoms. Thus, the significant
influence of the number of methylene groups in com-
plexes ligated by dithioether ligands R2S(CH)nSR2 on
the conformation and molecular structure has been
extensively studied [6]. In the context of our work on
enhance the stability of the dative M1
/
SR2 bond.
Numerous literature known dithioether ligands
R2SXnSR2 contain mostly CH2-groups as spacer units.
More recently, chiral dithioether complexes have been
* Corresponding authors. Tel.: ꢂ
/
49-931-888 4613; fax: ꢂ49-931-
/
organosilicon compounds [7ꢀ
silyl complexes, [10ꢀ13] we have prepared a series of
organosilanes functionalized by phenylthiomethyl
/9] and transition metal
888 4605.
E-mail addresses: michael.knorr@univ-fcomte.fr (M. Knorr),
c.strohmann@mail.uni-wuerzburg.de (C. Strohmann).
/
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0020-1693(02)01519-0

456
M. Knorr et al. / Inorganica Chimica Acta 350 (2003) 455ꢀ466
/
PhSCH2-, phenyltelluromethyl PhTeCH2- and butyltel-
luromethyl BuTeCH2-substituents. In order to evaluate
the influence of silicon in these potentially chelating
2JH,Si
ꢁ7.2 Hz), 2.35, 2.38 (AB-system, 4H, SiCH2S
/
3
JABꢁ
3JH,H
/
12.5 Hz, JH,H
3.3 Hz), 7.0ꢀ
7.35 (m, 10 H; SC6H5). 13C{1H}
6.3 (SiCH3), 14.4 (2 C) (SiCH2S), 125.2 (2
ꢁ
/
3.1 Hz), 4.19 (m, 1H, SiH,
ꢁ
/
/
ligand systems of the type Rꢀ
/
Eꢀ
/
CH2ꢀ
/
SiR2ꢀ
/
CH2ꢀ
/
Eꢀ
/
R
NMR: dꢁ
/
ꢃ
/
(EꢁS, Te) for coordination chemistry, we have under-
/
C) (C-4 of SC6H5), 126.8 (4 C), 128.8 (4 C) (C-2/C-6 and
C-3/C-5 of SC6H5), 138.9 (2 C) (C-1 of SC6H5). 29Si{1H}
NMR: dꢁ
taken a study to ligate these dithioether and ditellur-
oether on various transition metals. An additional
aspect of this study was the utilization of dithioether
/
ꢃ14.0.
/
ligands bearing potentially reactive groups like Siꢀ
/
H or
2.1.1.2. Compound 1d. Anal. Calc. for C21H22SiS3
(398.7): C, 63.27; H, 5.56. Found: C, 63.1; H, 5.8%.
Siꢀvinyl functions. During this work was in progress, a
/
3
paper of Rheingold and Rabinovich describing the co-
ordination of the very related tridentate thioether
(PhSCH2)3SiMe (which has been independently pre-
pared by us [9]), on a Cr(CO)3 fragment appeared [14].
1H NMR: dꢁ
4.24 (septuplet, 1H, SiH, JH,H
/
2.45 (d, 6H, SiCH2S, JH,H
ꢁ
/
3.1 Hz),
7.35 (m,
12.9 (3 C) (SiCH2S),
3
ꢁ
/
3.1 Hz), 7.0ꢀ
/
15 H; SC6H5). 13C{1H} NMR: dꢁ
/
125.5 (3 C) (C-4 of SC6H5), 127.2 (6 C), 128.9 (6 C) (C-2/
C-6 and C-3/C-5 of SC6H5), 138.2 (3 C) (C-1 of SC6H5).
29Si{1H} NMR: dꢁ
/
ꢃ14.6.
/
2. Experimental
2.1.2. Preparation of (PhTeCH2)2SiMe2 (2a) and
(BuTeCH2)2SiMe2 (2b)
All reactions were performed in Schlenk-tube flasks
under purified nitrogen. Solvents were dried and dis-
tilled under nitrogen before use, toluene and hexane
over sodium, dichloromethane from P4O10. Nitrogen
was passed through BASF R3-11 catalyst and molecular
sieve columns to remove residual oxygen and water. IR
spectra have been recorded on a Nicolet Nexus 470
spectrometer. Elemental C, H analyses were performed
on a Leco Elemental Analyzer CHN 900. The 1H,
13C{1H}, 31P{1H}, 125Te{1H} and 29Si{1H} NMR
spectra were recorded at 200.13, 50.32, 81.01, 63.16
and 39.76 MHz, respectively, on a Bruker ACP 200
instrument and a Bruker Avance 300 instrument (300.13
A cooled solution of 0.16 mol of RTeLi (Rꢁ
butyl) in 200 ml of THFꢀhexane, prepared from Te and
n-BuLi or PhLi in THF, was added at ꢃ78 8C to a
/phenyl,
/
/
solution of 0.08 mol of bis(chloromethyl)dimethylsilane
in 60 ml of THF. The reaction mixture was warmed to
r.t., the solvent removed in vacuo and the reaction
mixture extracted with hexane. The solvent was evapo-
rated in vacuum, and the oily residue was purified by
Kugelrohr distillation.
2.1.2.1. Compound 2a. Boiling point (b.p.): 151 8C/10ꢃ3
mm (oven temperature); yellowish oil. Yield 81%. Anal.
Calc. for C16H20SiTe2 (476.5): C, 38.77; H, 4.07. Found:
1
MHz for H). 195Pt chemical shifts were measured on a
1
Bruker ACP 200 instrument (42.95 MHz) and externally
referenced to K2PtCl4 in water with downfield chemical
shifts reported as positive. NMR spectra were recorded
in pure CDCl3, unless otherwise stated. The reactions
were generally monitored by IR spectroscopy in the
n(CO) region for the rhenium derivatives.
C, 38.90; H, 4.0%. H NMR: dꢁ
/
0.23 (s, 6H, SiCH3,
2JH,Si
2JH,Si
NMR: dꢁ
ꢁ
/
6.4 Hz), 2.13 (s, 4H, TeCH2Si, 2JH,Te
4.9 Hz), 7.1ꢀ
9.9 (s, SiCH2Te, JC,Te
6.4 Hz), ꢃ
ꢁ/11.7 Hz,
ꢁ
/
/
7.75 (m, 10 H; TeC6H5). 13C{1H}
1
1
/
ꢃ
ꢁ
/
ꢁ
/
174 Hz, JC,Si
ꢁ
/
3
1
50 Hz, JC,Te
3JC,Te
127.2 (C-4 of TeC6H5), 129.1 (C-3 of TeC6H5), 137.0 (C-
/
/
0.9 (s, SiCH3, JC,Si
ꢁ
291 Hz),
/54 Hz,
1
ꢁ
/
9 Hz), 113.1 (C-1 of TeC6H5, JC,Te
ꢁ
/
2
2.1. Preparations
2 of TeC6H5, JC,Te
365.5. 29Si{1H} NMR: dꢁ
ꢁ
/
22 Hz). 125Te{1H} NMR: dꢁ
/
2
5.9 (s, JSi,Te
/
ꢁ24 Hz).
/
2.1.1. Preparation of (PhSCH2)2SiHMe (1c) and
(PhSCH2)3SiH (1d)
A cooled solution of 0.24 mol of (phenylthio-
2.1.2.2. Compound 2b. B.p.: 140 8C/10ꢃ3 mm (oven
temperature); yellowish oil. Yield 87%. Anal. Calc. for
C12H28SiTe2 (455.6): C, 31.63; H, 6.19. Found: C, 31.91;
methyl)lithium in 200 ml of diethyl etherꢀ
prepared from thioanisole and n-BuLi in diethyl ether,
was added at ꢃ40 8C to a solution of 0.08 mol of
/hexane,
1
2
H, 6.10%. H NMR: dꢁ
/
0.14 (s, JH,Si
ꢁ
/
6.5 Hz, 6 H;
14.6 Hz),
1.8 (m, 4H, n-
CH2CH2CH3), 1.71 (s, 4 H, SiCH2Te), 2.61 (t,
4H, n-butylꢀ 15.1 Hz).
CH2CH2CH2CH3, 3JH,H
13C{1H} NMR: dꢁ 16.2 (1JC,Te
171.0 Hz, JC,Si
7 Hz; SiCH2Te), ꢃ 54 Hz,
1.1 (1JC,Si
8.4 Hz; SiCH3), 4.4 (1JC,Te
155 Hz; TeCH2C),
13.4 (CCH3), 25.0 (3JC,Te
11.0 Hz, CCH2CH3), 33.9
(2JC,Te 10.4 Hz, TeCH2CH2C). 125Te{1H} NMR: dꢁ
143.1. 29Si{1H} NMR: dꢁ5.6 (2JSi,Te
23 Hz).
3
/
SiCH3), 0.87 (t, 6H, n-butylꢀ
1.2ꢀ1.5 (m, 4H, n-butylꢀ
butylꢀ
/CH3, JH,H
ꢁ
/
trichlorosilane or 0.12 mol of methyldichlorosilane in 30
ml of diethyl ether. The reaction mixture was warmed to
room temperature (r.t.) and filtered. The solvent was
evaporated in vacuo, and the residue was purified by
Kugelrohr distillation.
/
/
CH2CH3), 1.5ꢀ
/
/
/
ꢁ
/
1
/
ꢃ
/
ꢁ
/
ꢁ
/
3
51.0 Hz, JC,Te
3JC,Te
ꢁ
/
/
ꢁ
/
ꢁ
/
ꢁ
/
2.1.1.1. Compound 1c. Anal. Calc. for C15H18SiS2
(290.5): C, 62.02; H, 6.24. Found: C, 61.7; H, 6.3%.
ꢁ
/
ꢁ
/
/
3
1H NMR: dꢁ
/
0.34 (d, 3H, SiCH3, JH,H
ꢁ/3.3 Hz,
/
ꢁ
/

M. Knorr et al. / Inorganica Chimica Acta 350 (2003) 455ꢀ
/466
457
2.1.3. Preparation of PtCl2{(PhSCH2)2SiPh2} (3)
To a suspension of [PtCl2(PhCN)2] (471.8 mg, 1
mmol) in 8 ml of toluene was added 1a (428 mg, 1
mmol). The solution was stirred at 75 8C for 48 h. The
solvent then was removed under reduced pressure and
the residue rinsed with hexane. Recrystallization from
hexane gave a white powder, which was filtered off and
dried under vacuum (35 mg, 27% yield). Anal. Calc. for
C18H18BrO3ReS2Si (640.1): C, 33.75; H, 2.83. Found: C,
33.91; H, 3.04%. IR (CH2Cl2): n(Siꢀ
/
H): 2159m, n(CO):
H): 2148w,
2036s, 1946s, 1908s cmꢃ1. (KBr): n(Siꢀ
/
1
n(CO): 2028s, 1940s, 1886s cmꢃ1. H NMR: dꢁ
/0.46
3
dichloromethaneꢀ/hexane gave yellow crystals, which
(d, 3H, CH3Si, JH,H
3JH,H
1H, Siꢀ
21.92 (s, Si).
ꢁ
/
3.5 Hz), 0.53 (d, 3H, CH3Si,
were filtered off and dried under vacuum (619 mg, 89%
yield). Anal. Calc. for C26H24Cl2PtS2Si (695.69): C,
1
44.96; H, 3.46. Found: C, 44.77; H, 3.65%. H NMR
ꢁ
/
3.8 Hz), 3.78 (m, HA), 2.45 (m, HB), 4.32 (m,
/
H), 4.48 (m, 1H, Siꢀ
/
H). 29Si{1H} NMR: dꢁ
/
ꢃ
/
(233K): invertomer I dꢁ
/
3.64 (d, 2H, HA, 2JH ,H
ꢁ13.4
/
A
B
2
Hz), 3.06 (d, 2H, HB, JH ,H
ꢁ/13.4 Hz). Invertomer II
A
2.90 (d, 2H, HA, JH ,HBꢁ
/13.8 Hz), 3.06 (d, over-
2.1.7. Preparation of
PtH{(PhSCH2)2Si(CH3)}(PPh3)2 (5a)
To a solution of [Pt(PPh3)2(C2H4)] (750 mg, 1 mmol)
in 10 ml of toluene was added 1c (348 ml, 1.2 mmol). The
solution was stirred at r.t. for 20 min and then
concentrated to approximately 3 ml under reduced
2
dꢁ
/
A
B
lapped with the signal of HA of invertomer I). 195Pt{1H}
NMR: dꢁ
/
ꢃ
/
2167 (s, Pt), ꢃ2197 (s, Pt).
/
2.1.4. Preparation of ReBr(CO)3{(PhSCH2)2SiPh2}
(4a)
pressure. Crystallization in tolueneꢀhexane gave a pale
/
[Re(m-Br)(CO)3THF]2 (84 mg, 0.1 mmol) was dis-
solved in 10 ml of dichloromethane and 1a (86 mg, 0.2
mmol) was added to the solution. The reaction mixture
was stirred at r.t. for 45 min and then concentrated to
approximately 4 ml under reduced pressure. Addition of
hexane gave a white powder, which was filtered off and
dried under vacuum (120 mg, 77% yield). Anal. Calc. for
C29H24BrO3ReS2Si (778.1): C, 44.72; H, 3.08. Found: C,
44.33; H, 3.25%. IR (KBr): n(CO): 2035s, 1942s, 1897s
yellow powder, which was filtered off and dried under
vacuum (911 mg, 90% yield). Anal. Calc. for
C51H48P2PtS2Si (1010.19): C, 60.64; H, 4.8. Found: C,
1
H): 2066w. H
60.39; H, 5.01%. IR (KBr, cmꢃ1): n(Ptꢀ
/
3
4
NMR: dꢁ
/
ꢃ
/
0.04 (d, 3H, CH3, JPt,H
ꢁ
/
27 Hz, JP,H
11.0 Hz), 2.27 (d,
2.66 (dd, 1H, PtH,
ꢁ
/
2
2.4 Hz), 2.16 (d, 2H, HA, JH ,H
ꢁ
/
A
B
2
2H, HB, JH ,H
ꢁ
/
11.0 Hz), ꢃ
/
B2
19.6 Hz, JP,H
1
A
2JP,H
ꢁ
/
ꢁ
/
152.7 Hz, JPt,H
ꢁ
/
972.3 Hz).
67 Hz), 23.4
13C{1H} NMR: dꢁ
/
2.6 (s, C, CH3, 2JPt,C
ꢁ
/
1
2
cmꢃ1. H NMR: dꢁ
/
2.83 (d, HA, 2H, JH ,H
ꢁ12.2
/
2
(s, 2C, CH2, JPt,C
dꢁ30.8 (d, P, PPh3, JP,P
33.2 (d, P, PPh3, JP,P
195Pt{1H} NMR (C6D6): dꢁ
ꢁ
/
94 Hz). 31P{1H} NMR (243 K):
A
B
2
Hz), 4.29 (d, HA, 2H, JH ,H
12.2 Hz). 29Si{1H}
2
1
ꢁ
/
A
B
/
ꢁ
/
13 Hz, JPt,P
ꢁ
ꢁ
/
2509 Hz),
1682 Hz).
2
1
NMR: dꢁ
/
ꢃ13.9 (s, Si).
/
ꢁ
/
13 Hz, JPt,P
/
1
3410 (dd, Pt, JPt,P
/
ꢃ
/
ꢁ
/
1
2.1.5. Preparation of
ReBr(CO)3{(PhSCH2)2Si(CH3)(CHꢁ
and 4b?)
1647 Hz, JPt,P
ꢁ/2531 Hz).
/
CH2)} (4b
2.1.8. Preparation of PtH{(PhSCH2) (5b)
[Re(m-Br)(CO)3THF]2 (100 mg, 0.118 mmol) was
dissolved in 5 ml of dichloromethane and 1b (82 ml,
0.26 mmol) was added to the solution. After stirring at
r.t. for 1 h, the solvent was removed under vacuum and
the oily residue was washed with petroleum ether. The
product was obtained as a white powder, which was
dried in vacuum (116 mg, 74% yield). Anal. Calc. for
C20H20BrO3ReS2Si (666.1): C, 36.03; H, 3.00. Found: C,
35.82; H, 3.21%. IR (KBr): n(CO): 2034s, 1942s, 1888s
Compound 5b was obtained in an analogous manner
by reaction of [Pt(PPh3)2(C2H4)] with 1d and isolated in
48% yield. Anal. Calc. for C57H52P2PtS2Si (1118.33): C,
1
61.22; H, 4.69. Found: C, 61.18; H, 4.86%. H NMR:
3
2.41 (s, 6H, CH2, JPt,H
dꢁ
/
ꢁ
/
23.5 Hz), ꢃ3.21 (dd, 1H,
/
2
2
1
155.3 Hz, JPt,H
PtH, JP,H
Hz). 31P{1H} NMR: dꢁ
1JPt,P
1JPt,P
ꢁ
/
21.2 Hz, JP,H
ꢁ
/
ꢁ
/
934.5
14 Hz,
14 Hz,
3570
/
29.8 (d, P, PPh3, 2JP,P
ꢁ
/
2
ꢁ
ꢁ
/
2518 Hz), 31.0 (d, P, PPh3, JP,P
1756 Hz). 195Pt{1H} NMR (C6D6): dꢁ
ꢁ
/
1
2
cmꢃ1. H NMR: dꢁ
/
2.42 (d, 2H, HA, JH ,H
ꢁ
/
11.9
2.56 (d,
/
/
ꢃ
/
1
1
A
Hz) and 3.89 (d, 2H, HB, 2JH ,H
2
2H, HA, JH ,H
ꢁ
/
11.9 Hz); dꢁB
ꢁ11.9 Hz) and 3.72 (d, 2H, HB,
/
(dd, Pt, JPt,P
ꢁ
/
2522 Hz, JPt,P
ꢁ1757 Hz).
/
A
B
/
A
B
2JH ,H
ꢁ
/
11.9 Hz), 0.48 (s, 3H, CH3), 0.53 (s, 3H,
2.1.9. Preparation of PtCl2(PhTeCH2)2SiMe2)} (6a)
A solution of [Pt(Cl)2(PhCN)2] (236 mg, 0.5 mmol) in
10 ml of CH2Cl2 was treated with 2a (428 mg, 0.5 mmol)
and stirred for 1 day at ambient temperature. All
volatiles were removed under reduced pressure and the
residue rinsed with hexane. Recrystallization from
A
B
CH3), 5.96ꢀ6.33 (m, 6H, CHꢁCH2).
/
/
2.1.6. Preparation of
ReBr(CO)3{(PhSCH2)2Si(CH3)H} (4c and 4c?)
[Re(m-Br)(CO)3THF]2 (84 mg, 0.1 mmol) was dis-
solved in 10 ml of dichloromethane and 1c (63.8 ml, 0.22
mmol) was added to the solution. The reaction mixture
was stirred at r.t. for 45 min and then concentrated to
approximately 3 ml under reduced pressure. Addition of
CH2Cl2ꢀhexane gave a yellow microcystalline powder,
/
which was filtered off and dried under vacuum (339 mg,
89% yield). Anal. Calc. for C16H20Cl2PtSiTe2 (761.62):
C, 25.23; H, 2.65. Found: C, 25.45; H, 2.67%.

458
M. Knorr et al. / Inorganica Chimica Acta 350 (2003) 455ꢀ466
/
2.1.10. Preparation of [PtCl2(BuTeCH2)2SiMe2)} (6b)
A solution of [Pt(Cl)2(PhCN)2] (471.8 mg, 1 mmol) in
10 ml of CH2Cl2 was treated with 2b (456 mg, 1 mmol).
and stirred for 1 day at ambient temperature. All
volatiles were removed under reduced pressure and the
residue rinsed with hexane. Recrystallization from
model. H1 of compound 5 bonded to Pt was refined free
with an isotropic displacement parameter. Quite reason-
able bond length and bond angles were obtained for H1,
although hydrogen atoms can’t be localized certainly
near heavy atoms like Pt. Refinement of the structures
was carried out by full-matrix least-squares methods
based on Fo2 using SHELXL-97. All calculations were
performed using the WINGX crystallographic software
package, using the programs SHELXS-97 and SHELXL-97
[15]. The crystallographic data for each complex are
given in Table 5. The figures were drawn using
SCHAKAL-99.
CH2Cl2ꢀ
/
hexane gave air stable orangeꢀyellow crystals
/
(512 mg, 71% yield). Anal. Calc. for C12H28Cl2PtSiTe2
(721.64): C, 19.97; H, 3.91. Found: C, 19.99; H, 3.83%.
1H NMR: dꢁ
/0.23 (s, SiMe), 0.25 (s, SiMe2), 0.29 (s,
SiMe), 0.87 (t, n-butylꢀCH3), 1.38 (m, n-butylꢀ
/
/
CH2CH3), 1.70 (m, n-butylꢀ
/
CH2CH2CH3), 1.85 (m, n-
CH2CH2CH2CH3), 3.10 (m, TeCH2Si). 195Pt{1H}
butylꢀ
/
1
NMR: dꢁ
125Te{1H} NMR: dꢁ
Hz). 29Si{1H} NMR: dꢁ
Hz).
/
ꢃ
/
2652 (s, JPt,Te
ꢁ
/
1063 Hz), ꢃ
/
2665 (s).
1063
21
1
/436.7 (s), 398.8 (s, JPt,Te
ꢁ
/
3. Results and discussion
/
11.0 (s), 7.1 (s) (2JSi,Te
ꢁ
/
3.1. Synthesis of the dithio- and ditelluroether ligands
2.1.11. Preparation of ReBr(CO)3{(n-
BuTeCH2)2SiMe2} (7)
The [(phenylthio)methyl]hydridosilanes (1c,d) were
prepared in analogy to the published synthesis of 1a,b
by reaction of [(phenylthio)methyl]lithium with Cl2Si-
Me(H) or Cl3SiH [7b]. Compound 1c was isolated as a
yellowish oil, 1d was obtained as a waxy solid. The
ditelluroether ligands (PhTeCH2)2SiMe2 (2a) and (n-
BuTeCH2)2SiMe2 (2b) were obtained as yellowish, bad
smelling oils by reaction of LiTeR with bis(chloro-
methyl)dimethylsilane according Scheme 1. The detailed
multinuclear NMR data of 1c,d and 2a,b are presented
in Section 2.
To a solution of [Re(m-Br)(CO)3THF]2 (84 mg, 0.1
mmol) in 10 ml of dichloromethane was added 2b (91
mg, 0.2 mmol). The reaction mixture was stirred at r.t.
for 15 min and then concentrated to 2 ml under reduced
pressure. Addition of hexane gave a white powder,
which was filtered off and dried under vacuum (111 mg,
69% yield). Anal. Calc. for C15H28BrO3ReSiTe2
(805.78): C, 22.36; H, 3.50. Found: C, 22.69; H,
3.65%. IR (CH2Cl2): n(CO): 2022vs, 1933s, 1886vs
cmꢃ1
.
3.2. Synthesis of platinum and rhenium complexes with
chelating (phenylthiomethyl)silane ligands
2.2. Crystal structure determinations
A suitable crystal of each complex was mounted in a
glass capillary and used for X-ray crystal structure
determinations at 293(2) K. Data of 3 and 6b were
collected on a Siemens AED2 diffractometer using
In order to study the ability of the (phenylthio-
methyl)silanes (1) to chelate metal complexes and the
stereochemical problems associated with, we first pre-
pared simple model compounds using diphenylbis[(phe-
nylthio)methyl]silane (1a). Upon reaction of 1a with
[PtCl2(PhCN)2] in toluene, the very stable yellow square
planar chelate complex cis-[PtCl2{(PhSCH2)2SiPh2}] (3)
graphite-monochromated Mo Ka radiation (lꢁ
/
˚
0.71069 A). The intensities were collected using V ꢀ2u
/
scans, and the intensities of three standard reflections,
which were measured after every 100 reflections, re-
mained stable throughout each data collection. The
intensities were corrected for Lorentz and polarization
effects. An empirical absorption correction based on the
C-scans of three reflections was employed: Data of 4a
and 5a were collected on a Stoe IPDS diffractometer.
The intensities were determined and corrected by the
program INTEGRATE in IPDS (Stoe and Cie, 1999). An
empirical absorption correction was employed using the
FACEIT-program in IPDS (Stoe and Cie, 1999).
The structures were generally solved by direct and
Fourier methods using SHELXS-97. For each structure,
the non-hydrogen atoms were refined anisotropically.
All of the H-atoms were placed in geometrically
calculated positions and each was assigned a fixed
isotropic displacement parameter based on a riding-
Scheme 1.

M. Knorr et al. / Inorganica Chimica Acta 350 (2003) 455ꢀ
/466
459
1
was isolated. H NMR investigations at variable tem-
perature showed, that due to a facile inversion process at
the sulfur atoms in solution, meso- and DL-isomers
coexist in a temperature dependent equilibrium (Scheme
2). At 325 K the pyramidal inversion is sufficiently fast
so that only one ‘averaged planar’ conformation is
observed resulting in singlet for the methylene protons
at d 3.11 with a 3JPt,H coupling of 54 Hz. At 298 K, the
signal has collapsed to a very broad hump. Progressive
cooling of the solution resulted in a separation in two
distinct resonances for the methylene protons. The
observation of two mutually coupled doublets at d
3.64 and 3.06 (2JH ,H
ꢁ13.4 Hz) at 233 K indicates that
/
A
B
Fig. 1. View of the molecular structure of 3.
the inversion process is frozen on the NMR time scale.
In addition to the first set of doublets, a second AB
system due a second isomer is present, the ratio being
Table 1
Selected bond lengths (pm) and bond angles (8) of 3
approximately 70:30. The coexistence of meso- and DL
-
isomers of 3 can also be deduced from the 195Pt{1H}
NMR spectrum, which displays at 298 K two singlets at
Bond lengths
Ptꢀ
Ptꢀ
Ptꢀ
Ptꢀ
S(1)ꢀ
S(2)ꢀ
S(1)ꢀ
S(2)ꢀ
/
S(1)
228.1(2)
227.1(2)
231.7(2)
232.5(2)
182.2(6)
182.2(6)
179.3(7)
179.8(7)
189.5(6)
188.3(7)
d ꢃ
/
2167 and ꢃ2197 in an approximate 60:40 ratio.
/
/S(2)
/Cl(1)
/Cl(2)
3.2.1. Crystal structure of 3
/C(1)
/C(2)
Suitable single crystals were grown from CH2Cl2ꢀ
hexane. Fig. 1 shows a platinum(II) center in a square
planar environment with a cis-arrangement of the two
/
/C(15)
/C(21)
Siꢀ
/
C(1)
chloro ligands [Cl(1)ꢀ
/
Ptꢀ
/
Cl(2)ꢁ90.02(8)8]. The root
/
Siꢀ
/
C(2)
mean square (RMS) deviation from the plane defined by
˚
S(2) amounts to 0.046 A. The six-
Bond angles
Cl(1)ꢀ
/
Cl(2)ꢀ
/
Ptꢀ
/
S(1)ꢀ
/
Cl(1)ꢀ
Cl(1)ꢀ
Cl(2)ꢀ
Cl(1)ꢀ
Cl(2)ꢀ
S(1)ꢀPtꢀ
C(1)ꢀS(1)ꢀ
S(1)ꢀC(1)ꢀ
S(2)ꢀC(2)ꢀ
C(1)ꢀS(1)ꢀ
C(2)ꢀS(2)ꢀ
/
Ptꢀ
Ptꢀ
Ptꢀ
Ptꢀ
Ptꢀ
/
Cl(2)
S(1)
S(1)
S(2)
S(2)
90.02(8)
84.49(7)
174.49(6)
173.02(6)
85.20(7)
100.25(6)
109.8(2)
115.9(3)
118.4(4)
112.0(2)
108.4(2)
membered Ptꢀ
/
S(1)ꢀ
/
S(2)ꢀ
/
C(1)ꢀC(2)ꢀSi chelate ring
/
/
/
/
/
/
adopts a distorted chair conformation very similar to
that reported for cis-[PtCl2{PhS(CH2)3SPh}] ligated by
a 1,3-bis(phenylthio)propane ligand [16]. In contrast to
the latter complex, in which the phenyl substituents of
the sulfur atoms are in an anti-mode with respect to the
chelate ring, the two phenyl groups of 3 are syn-
orientated corresponding to a meso-conformation. The
/
/
/
/
/
/
S(2)
/
/
C(5)
/
/
Si
Si
Pt
Pt
/
/
/
/
/
/
Ptꢀ
227.1(2) pm parallel that of [PtCl2{PhS(CH2)3SPh}]
[227.1(2) and 227.42(19) pm]. The averaged PtꢀCl
/
S(1) and Ptꢀ/S(2) bond distances of 228.1(1) and
/
and two meso-conformations [6a,6b]. A stable chelate
complex of this type is also formed, when 1a is reacted
with [Re(m-Br)(CO)3THF]2 in CH2Cl2 (Scheme 3). Both
1H and 29Si NMR spectra of colorless fac-[Re-
Br(CO)3{(PhSCH2)2SiPh2}] (4a) indicate, that in con-
trast to the case of 3, in solution only one invertomer
bond length of 3 [232.1 pm] is also almost identical to
that of the 1,3-bis(phenylthio)propane counterpart
[232.5 pm] (Table 1).
Extensive NMR studies have been carried out in the
past on the [ReX(CO)3(RSÁ Á ÁSR) (Xꢁ
/
Cl, Br, I) to
study the sulfur inversion, which gives rise to two DL-
Scheme 2.

460
M. Knorr et al. / Inorganica Chimica Acta 350 (2003) 455ꢀ
/466
Scheme 3.
exists at ambient temperature. Thus, the proton NMR
spectrum of this off-white air stable compound consists
in a well defined AX pattern centered at d 4.29 and 2.83
at ambient temperature. Thus, the proton NMR dis-
plays two distinct sets of AX pattern for the methylene
protons and an overlapped multiplet for the vinyl
resonances. Rising the temperature to 50 8C in CDCl3
had no effect on the shape of the NMR signals.
The same case was encountered upon reaction of
[Re(m-Br)(CO)3THF]2 with (PhSCH2)2Si(H)Me (1c).
The IR spectrum of [ReBr(CO)3{(PhSCH2)2Si(H)Me}]
(4c) shows in addition to the three n(CO) stretches at
2036, 1946 and 1909 cmꢃ1 diagnostic for a fac-
arrangement, a band of medium intensity at 2159
(JH,H
protons. The absence of other conformational isomers is
ꢁ12.2 Hz) due to two mutually coupled CH2
/
also confirmed by the 29Si INEPT NMR spectrum,
which exhibits just a single resonance at d ꢃ
/
13.9 ppm
(1a d ꢃ11.3 ppm). At present we can not conclude,
/
whether the solution conformation of 4a corresponds to
the meso-ligand arrangement found in the solid state
structure of 4a (see below). Note, that the fac-[Re-
Br(CO)3{MeS(CH2)3SMe}], in which the dithioether
ligand forms also a six-membered chelate ring with a
ReBr(CO)3-fragment, is fluxional at ambient tempera-
ture [6a,6b]. At the moment, we cannot state which
steric and/or electronic parameter causes the augmenta-
tion of the barrier of pyramidal inversion at the S-donor
atoms in the case of 4. This may be due to the
replacement of a methylene unit by SiR2 or alternatively
due to the presence of phenyl substituents on S instead
of methyl groups.
cmꢃ1 assigned to a n(Siꢀ
that formation of the chelate complex 4c is preferred
instead of oxidative addition of the SiꢀH bond on Re
/H) vibration. This proves
/
(see below). The proton NMR data are indicative for the
formation of two stereochemically rigid diastereomers
4c and 4c? in a 50:50 ratio. Due the additional coupling
with Siꢀ
/
H, the two resonances of the SiMe groups at d
3
0.46 and 0.53 ppm are splitted in doublets by JH,H
couplings of 3.5 and 3.8 Hz, respectively. Selective
irradiation of the two broad Siꢀ
/
H signals at d 4.48
and 4.32 ppm permitted to correlate the SiMe resonance
at d 0.46 ppm with that at 4.32 ppm and the SiMe
resonance at d 0.53 ppm with that at 4.48 ppm.
When [Re(m-Br)(CO)3THF]2 was reacted with
(PhSCH2)2Si(vinyl)Me (1b) in CH2Cl2, two diastereo-
mers fac-[ReBr(CO)3{(PhSCH2)2SiMe(vinyl)}] (4b, 4b?)
were formed in a 50:50 ratio. Due to the dissymmetric
substitution on silicon, one diastereomer possesses the
3.2.2. Crystal structure of 4a
vinyl group directed towards the Reꢀ
/
Br (4b), the second
Br
Suitable single crystals were grown from CH2Cl2ꢀ
/
one (4b?) the methyl group directed towards the Reꢀ
/
hexane. Fig. 2 shows a rhenium(I) center in an
octahedral environment with a facial arrangement of
the three carbonyl ligands. The diphenylbis[(phe-
bond. As in the case of 4a, the NMR data of 4b, 4b?
indicate that the two isomers are stereochemically rigid

M. Knorr et al. / Inorganica Chimica Acta 350 (2003) 455ꢀ
/466
461
Table 2
Selected bond lengths (pm) and bond angles (8) of 4a
Bond lengths
Reꢀ
Reꢀ
Reꢀ
/
S(1)
S(2)
Br
251.0(2)
252.0(2)
262.93(11)
181.8(7)
179.3(6)
188.1(7)
189.2(6)
/
/
S(1)ꢀ
/C(4)
S(2)ꢀ
/C(5)
Siꢀ
Siꢀ
/
C(4)
/C(5)
Bond angles
C(3)ꢀ
C(1)ꢀ
C(2)ꢀ
C(3)ꢀ
C(1)ꢀ
C(2)ꢀ
S(1)ꢀReꢀ
C(3)ꢀReꢀ
C(1)ꢀReꢀ
C(2)ꢀReꢀ
S(1)ꢀReꢀ
S(2)ꢀReꢀ
C(4)ꢀ
C(5)ꢀ
S(1)ꢀC(4)ꢀ
S(2)ꢀC(5)ꢀ
/
Reꢀ
Reꢀ
Reꢀ
Reꢀ
Reꢀ
Reꢀ
/
S(1)
S(1)
S(1)
S(2)
S(2)
S(2)
176.2(2)
95.7(2)
88.9(2)
/
/
/
/
/
/
93.6(2)
/
/
177.4(2)
86.7(2)
/
/
/
/
S(2)
83.04(5)
90.5(2)
/
/
Br
Br
Br
/
/
91.3(2)
/
/
177.6(2)
91.14(5)
90.91(4)
109.8(2)
111.9(2)
119.2(3)
111.9(3)
Fig. 2. View of the molecular structure of 4a.
/
/Br
/
/Br
/
S(1)ꢀ
/
Re
/
S(2)ꢀ
/
Re
Si
nylthio)methyl]silane ligand forms a six-membered cycle
with the rhenium center adopting a chair conformation.
The phenyl rings of the thioether groups are both syn-
orientated in the same direction as the bromo ligand
/
/
/
/
Si
corresponding to a meso-invertomer. The Reꢀ
lengths of 251.0(2) and 252.0(2) pm are close to that
reported for [ReBr(CO)3{(ꢀCH2S(CH2)Cl)}] (252.5(3)
/
S bond
displaying a bridging bonding mode, or (iii) to attach a
second metal center by formation of inorganic ring
systems of type (C).
/
and 253.7(2) pm), the Reꢀ
/
Br bond distance of
The pioneering work of Eaborn on platinum silyl
complexes has shown, that a wide range of commercially
available hydridosilanes can be oxidatively added on
262.93(11) pm is somewhat longer compared with the
latter complex [260.87(10) pm] [3] (Table 2).
[Pt(PPh3)2(CH2ꢁ
/
CH2)] to afford hydrido silyl com-
plexes of the type cis-[Pt(H)(SiR3)(PPh3)2] [17]. NMR
studies at variable temperature on cis-[Pt(H)(SiPh3)-
(PPh3)2] have revealed that this complex is fluxional in
solution [18]. This fluxionality is due to an temperature
depend equilibrium between a square-planar Pt(II)
3.3. Synthesis of platinum hydrido silyl complexes
The oxidative addition of tertiary hydridosilane Hꢀ
SiR3 on transition metal centers offers a convenient
method to generate hydrido silyl complexes of the type
/
species [Pt(H)(SiR3)(PPh3)2] and a Pt(0) species [(Hꢀ
SiR3)Pt(PPh3)2] having a side-on coordinated HꢀSiR3
ligand.
As expected, the Siꢀ
oxidative addition towards low valent metal centers such
/
LnM(H)SiR3. Our aim was to extend this Siꢀ
/
H activa-
/
tion route using functionalized hydridosilanes bearing
donor groups in order to achieve (i) an intramolecular
coordination in monometallic complexes (A), (ii) to
synthesize and stabilize bimetallic complexes of type (B)
/
H bond of 1c is reactive for

462
M. Knorr et al. / Inorganica Chimica Acta 350 (2003) 455ꢀ466
/
Scheme 4.
Fig. 3. View of the molecular structure of 5a.
as Pt(0). The stable yellow platinum complex [Pt(H)-
(PPh3)2{Si(CH2SPh)2Me}] (5a) was prepared in high
Maybe this subtle electronic modification combined
with the increased steric bulkiness of SiR3 is sufficient
to stabilize a Pt(II) center.
yield by reaction of [Pt(PPh3)2(CH2ꢁ/CH2)] with an
excess of 1c under mild conditions according to Scheme
4.
The fluxional complex 5a has been fully characterized
in solution by multinuclear NMR techniques. In CDCl3
at 243 K, the data are consistent with a cis-arrangement
of the hydride and the silyl ligand. In the proton NMR
spectrum of 5a, the hydride resonance is found at d
3.3.1. Crystal structure of 5a
Suitable single crystals were grown from tolueneꢀ
hexane. Fig. 3 shows a platinum(II) center in a severely
distorted square-planar environment with a cis-arrange-
/
ment of the two PPh3 ligands, the angles P(2)ꢀ
/
Ptꢀ
/
P(1)
ꢃ
/
2.66 and consists of a doublet of doublet (2JP,H
19.6, 152.7 Hz), which is flanked by platinum satellites
(1JPt,H 972.3 Hz). Due to a trans-coupling 4JP,H of 2.4
Hz, the SiMe resonance at d ꢃ0.04 is splitted in a
ꢁ
/
and P(2)ꢀPtꢀSi [107.52(5) and 97.80(5)8] being substan-
/
/
tially larger than the 908 expected for an ideal square-
planar geometry. There is, however, no significant
deviation from planarity, since the RMS deviation
from the plane defined by P(1), P(2), Pt and Si is only
ꢁ
/
/
3
doublet with an additional JPt,H coupling of 27.0 Hz.
At ambient temperature, all resonances give rise to
broad signals without any fine structure. Similarly, in
the 31P{1H} NMR spectrum the two broadened reso-
nances of the PPh3 ligands have lost their mutual
coupling at ambient temperature. However, at 243 K
the expected well resolved AX-pattern at d 30.8 and
˚
0.057 A. Although there is some electron density close to
Pt, which could be refined for a hydride position, a
precise localization of a hydride ligand in the proximity
of a heavy atom is not possible. Therefore, the given Ptꢀ
/
H(1) bond distance of 153.8 pm of 5a may have much
impreciseness. For comparison, 154.4 pm have been
determined for the bimetallic complex [(OC)3Fe{Si(O-
Me)3}(m-Ph2PNHPPh2)Pt(H)(PPh3)] [13]. The overall
geometry of 5a is quite similar to that of cis-
2
1
33.2.with a JP,P of 13 Hz is observed. The JPt,P
couplings of 2509 and 1682 Hz are also present in the
195Pt{1H} NMR spectrum of 5a giving rise to a doublet
[Pt(H)(SiPh3)(PPh3)2] [20], the Ptꢀ
/
Si bond length of
of doublets centered at d ꢃ3410 ppm.
/
5a [235.59(12) pm] being almost identical with that
of the triphenylsilyl counterpart [235.7(3) pm].
The single crystal X-ray determination reveals further-
more, that in the solid state intramolecular short
contacts between a thioether group and the platinum
In an analogous manner, the stable derivative 5b was
obtained after oxidative addition of (PhSCH2)3SiH (1d)
on Pt(0). Surprisingly, both phosphorous and proton
NMR spectra are well resolved and easy to interpret due
to the symmetry of the silyl moiety. These findings let
suggest that 5b is almost rigid at ambient temperature.
Extended studies on hydrido-silyl manganese have
evidenced that electron withdrawing substituents on Si
favor pronounced oxidative addition on the reaction
trajectory starting with non classical silane adducts
center are absent, the closest Ptꢀ
/
S distance being 4.146
˚
A (Table 3).
3.4. Synthesis of platinum complexes with chelating
ditelluroether ligands
[CpMn(I)(CO)2(Hꢀ
/
SiR3)] to complete oxidative addi-
tion leading finally to [CpMn(III)(CO)2(H)SiR3)] [19].
In the case of 5a,b, the third CH2SPh substituent is
slightly more electron withdrawing compared with CH3.
For comparison with the dithioether complex cis-
[PtCl2(PhSCH2)2SiPh2)] (3), we were interested in to
synthesize related ditelluroether chelate complexes. The

M. Knorr et al. / Inorganica Chimica Acta 350 (2003) 455ꢀ
/466
463
Table 3
Selected bond lengths (pm) and bond angles (8) of 5a
the two n-butyl groups are orientated in the same sense,
rendering the two methyl groups on Si non-equivalent.
Therefore, they give rise to two singlets with the
appearance of a ‘pseudo-doublet’. Rising the tempera-
ture to 313 K has no significant effect on the shape of
the over all proton NMR spectrum, the integration ratio
between the SiMe2 singlet of the DL-invertomer and the
‘pseudo-doublet’ of the meso-invertomer being approxi-
mately 70:30.
Bond lengths
Ptꢀ
Ptꢀ
Ptꢀ
S(1)ꢀ
S(1)ꢀ
S(2)ꢀ
S(2)ꢀ
/
P(2)
P(1)
Si
231.04(13)
234.54(11)
235.59(12)
175.9(5)
180.5(5)
176.1(5)
179.0(5)
188.6(5)
190.3(5)
191.8(5)
/
/
/
C(3)
C(2)
C(10)
C(9)
/
/
/
The 195Pt{1H} NMR spectrum, which displays two
Siꢀ
Siꢀ
Siꢀ
/
C(1)
C(2)
C(9)
/
broadened singlets at d ꢃ
/
2652 and ꢃ2665 in an
/
/
approximate 3:1 ratio, the first being intense enough
1
to determine a JPt,Te coupling of 1063 Hz. The same
Bond angles
P(2)ꢀ
P(2)ꢀ
P(1)ꢀ
C(3)ꢀ
C(10)ꢀ
C(1)ꢀSiꢀ
C(1)ꢀSiꢀ
C(2)ꢀSiꢀ
C(1)ꢀSiꢀ
C(2)ꢀSiꢀ
C(9)ꢀSiꢀ
S(1)ꢀ
S(2)ꢀ
/
Ptꢀ
Ptꢀ
Ptꢀ
/
P(1)
107.52(5)
97.80(5)
153.42(4)
105.2(2)
105.3(2)
106.3(2)
100.3(2)
105.0(2)
121.3(2)
112.6(2)
109.59(14)
111.8(2)
113.2(2)
1JPt,Te coupling of 1063 Hz was also found in the
125Te{1H} NMR spectrum, which exhibits two singlets
at d 436.7 and 398.8 in an approximate 1:3 ratio (2b
143.1 ppm). The same 1:3 intensity ratio was also
encountered in the 29Si INEPT NMR spectrum (Fig.
4), which showed two singlets at d 11.0 and 7.1. The
later resonance is flanked by tellurium satellites with an
averaged 2JSi,Te coupling of 21 Hz. For comparison, the
ligand 2b gives rise to a singlet at d 5.6 with an averaged
2JSi,Te coupling of 23 Hz.
/
/Si
/
/Si
/
S(1)ꢀ
/
C(2)
C(9)
/
S(2)ꢀ
/
/
/
C(2)
C(9)
C(9)
Pt
/
/
/
/
/
/
/
/
Pt
/
/
Pt
/
C(2)ꢀ
C(9)ꢀ
/
Si
Si
/
/
3.4.1. Crystal structure of 6b
Suitable single crystals were grown from CH2Cl2ꢀ
hexane. Fig. 5 shows a platinum(II) center in a square
planar environment with a cis-arrangement of the two
chloro ligands. The RMS deviation from the plane
telluro-congeners cis-[PtCl2(RTeCH2)2SiMe2)] (6a Rꢁ
/
/
Ph, 6b Rꢁn-Bu) were readily formed upon reaction of
/
[PtCl2(PhCN)2] with a slight excess of 2a,b in CH2Cl2
with 89% yield (Scheme 5). Since the very stable yellow
complex 6a was not sufficient soluble in CDCl3 for
multinuclear NMR studies, we focussed our investiga-
tions on the much more soluble n-butyl derivative 6b. 1H
NMR studies at 295 K showed that the inversion barrier
at the tellurium atoms is low enough to observe meso-
and DL-isomers as encountered for 3. Thus, the SiMe2
groups give rise to singlet at d 0.25 ppm, which appears
in middle of two other SiMe resonances of equal
intensities. We tentatively attribute the singlet to
the DL-invertomer (see the molecular structure
below, possessing a C2 axes passing through Pt
and Si), for which the two methyl groups on Si should
be identical. In the case of a meso-conformation,
defined by Cl(1)ꢀ
/
Cl(2)ꢀ
/
Ptꢀ
/
Te(1)ꢀ
/
Te(2) amounts to
0.009 A. The dimethylbis[(butyltelluro)methyl]silane
˚
ligand forms a distorted six membered cycle with the
Pt center, the Ptꢀ
/
Te(1) and Ptꢀ
/
Te(2) bond distances
being 249.71(14) and 250.60(16) pm, respectively. The
two n-butyl groups are oriented in the opposite sense
corresponding to a DL-conformation. The averaged Ptꢀ
Te bond length of 250.15 pm parallels that of
[PtCl{MeS(CH2)3Te(CH2)3SMe}][PF6] [252.58(11) pm],
/
the averaged Ptꢀ/Cl bond length of 6b [234.4 pm] is very
comparable to that of the cationic complex [235.4 pm]
[21] (Table 4).
Scheme 5.

464
M. Knorr et al. / Inorganica Chimica Acta 350 (2003) 455ꢀ466
/
Fig. 4. 29Si INEPT NMR spectrum of 6b recorded in CDCl3.
Table 4
Selected bond lengths (pm) and bond angles (8) of 6b
Bond lengths
Ptꢀ
Ptꢀ
Ptꢀ
Ptꢀ
Te(1)ꢀ
Te(1)ꢀ
Te(2)ꢀ
Te(2)ꢀ
/
Te(1)
Te(2)
Cl(1)
Cl(2)
249.71(14)
250.60(16)
233.5(6)
/
/
/
235.3(5)
/
C(1)
C(5)
C(2)
C(9)
213.6(18)
216.1(18)
210.7(19)
213.6(18)
181.6(19)
183.0(19)
/
/
/
Siꢀ
/
C(4)
Siꢀ
/
C(3)
Bond angles
Cl(1)ꢀ
Cl(1)ꢀ
Cl(2)ꢀ
Cl(1)ꢀ
Cl(2)ꢀ
Te(1)ꢀ
C(1)ꢀTe(1)ꢀ
C(2)ꢀTe(2)ꢀ
C(1)ꢀTe(1)ꢀ
C(1)ꢀTe(1)ꢀ
C(2)ꢀTe(2)ꢀ
/
Ptꢀ
Ptꢀ
Ptꢀ
Ptꢀ
Ptꢀ
Ptꢀ
/
Cl(2)
Te(1)
Te(1)
Te(2)
Te(2)
90.3(3)
175.51(18)
85.25(18)
86.00(18)
176.19(18)
98.49(5)
109.8(2)
90.9(9)
/
/
/
/
/
/
Fig. 5. View of the molecular structure of 6b.
/
/
/
/
Te(2)
3.5. Synthesis of a rhenium complexes with a chelating
ditelluroether ligands
/
/
C(5)
C(9)
C(5)
Pt
/
/
/
/
92.1(8)
/
/
107.1(5)
107.6(5)
After addition of 2 equiv. of 2b to a solution of [Re(m-
Br)(CO)3THF]2 in CH2Cl2, IR monitoring indicated
instantaneous formation of fac-[ReBr(CO)3{(n-Bu-
TeCH2)2SiMe2}] (7). Compared with the dithioether
derivative 4c, the position of the three n(CO) stretching
modes at 2022, 1933 and 1895 cmꢃ1 is shifted approxi-
mately ten wave numbers to lower frequency. This is
probably due to the stronger donor ability of the n-BuTe
groups compared with the SPh groups of 4c (Scheme 6).
/
/Pt
4. Conclusion and perspectives
We have shown that dithioether and ditelluroether
ligands incorporating a silicon atom form stable com-
plexes with various transition metals. The ease of
variation of the substituents on Si offers a promising

M. Knorr et al. / Inorganica Chimica Acta 350 (2003) 455ꢀ
/466
465
Table 5
Crystallographic data for compounds 3, 4a, 5a, and 6b
Identification code
Empirical formula
Formula weight
Temperature (K)
SHELX816 5a
SHELXS967 6b
C12H28Cl2PtSiTe2
721.62
SHELXS826 4a
SHELX870 3
C
51H48P2PtS2Si
C29H24BrO3ReS2Si
778.80
293(2)
C26H24Cl2PtS2Si
694.65
293(2)
1010.13
293(2)
293(2)
0.71073
˚
Wavelength (A)
0.71073
triclinic
0.71073
monoclinic
P2(1)/n
0.71073
triclinic
Crystal system
Space group
Unit cell dimensions
triclinic
1
P/1
P
/
P/1
˚
a (A)
13.238(3)
13.628(3)
14.383(3)
72.31(3)
69.73(3)
77.82(3)
2302.7(9)
2
9.113(2)
9.740(2)
11.906(2)
93.68(3)
94.26(3)
91.18(3)
1051.3(4)
2
11.141(2)
21.754(4)
12.584(3)
90
10.476(2)
11.574(2)
12.709(3)
66.87(3)
66.43(3)
78.08(3)
1296.6(5)
2
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
Volume (A )
Z
107.40(3)
90
3
˚
2910.3(10)
4
1.777
Density (calculated) (Mg 1.457
mꢃ3
3.267
2.280
1.779
)
Absorption coefficient
9.691
660
5.762
1512
5.837
676
(mmꢃ1
)
F(000)
1016
Crystal size (mm3)
u Range for data
collection (8)
0.30ꢄ
/
0.20ꢄ
/0.20
0.20ꢄ
/
0.20ꢄ
/
0.10
0.20ꢄ
/
0.20ꢄ
/0.10
0.40ꢄ
/
0.40ꢄ0.20
/
1.56ꢀ27.50
/
2.24ꢀ23.98
/
2.13ꢀ26.30
/
2.16ꢀ24.12
/
Index ranges
ꢃ
17, 05
10 059
10 059
/
155
/
h 5
/
14, ꢃ
/
165
/
k 5
/
ꢃ
/
105
/
h 5
/
7, ꢃ
/
75
/
k 5
/
10,
ꢃ
ꢃ/
/
135
145
22 984
5529 [Rint
/
h 5
/
13, ꢃ
/
265
/
k 5
/
26,
ꢃ
/
125
12, ꢃ145
8311
3815 [Rintꢁ0.0617]
/
h 5
/
11, ꢃ
/
125
/
k 5
/
/
l 518
/
ꢃ
/
135
/
l 513
/
/
l 514
/
/
/
l 5
/14
Reflections collected
Independent reflections
Refinement method
3114
3114
ꢁ
/0.0537]
/
full-matrix least-squares
on F2
10 059/0/519
full-matrix least-squares on full-matrix least-squares on F2 full-matrix least-squares on
F2
3114/0/167
F2
3815/0/289
Data/restraints/para-
meters
Goodness-of-fit on F2
Final R indices
5529/0/335
1.029
0.913
1.075
1.036
R1ꢁ
R1ꢁ
1.930 and ꢃ
/
0.0365, wR2ꢁ
0.0432, wR2ꢁ
1.989
/
0.0976 R1ꢁ
0.1018 R1ꢁ
2.606 and ꢃ
/
0.0650, wR2ꢁ
0.0824, wR2ꢁ
2.949
/
0.1566
0.1627
R1ꢁ
/
0.0477, wR2ꢁ
/0.1233
R1ꢁ
R1ꢁ
1.800 and ꢃ
/
0.0389, wR2ꢁ
0.0398, wR2ꢁ
1.968
/
0.1073
0.1095
[I ꢀ2s(I)]
/
R indices (all data)
Extinction coefficient
/
/
/
/
R1ꢁ
0.0057(4)
1.873 and ꢃ
/
0.0546, wR2ꢁ
/0.1281
/
/
Largest difference peak
ꢃ3
/
/
/
2.273
/
˚
and hole (e A
)
Acknowledgements
We are grateful to the Deutschen Forschungsge-
meinschaft (DFG), the Fonds der Chemischen Industrie
(FCI) and the French Ministe`re de la Recherche et
Technologie for financial support.
Scheme 6.
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