The structurally characterised silyl complexes, Os(κ2-S2CNMe2)(SiMeCl2)(CO)(PPh3)2 and Os(κ2-S2CNMe2)(SiCl3)(CO)(PPh3)2, which have remarkably unreactive Si-Cl bonds

Article abstract of DOI:10.1016/j.jorganchem.2005.12.072

Treatment of Os(κ²-S₂CNMe₂)H(CO)(PPh₃)₂ with HSiMeCl₂ or HSiCl₃ gives in high yield Os(κ²-S₂CNMe₂)(SiMeCl₂)(CO)(PPh₃)₂ (1) or Os(κ²-S₂CNMe₂)(SiCl₃)(CO)(PPh₃)₂ (2), respectively. The crystal structures of both compounds have been determined and the Os-Si distances are 2.3672(10) A? for 1 and 2.3449(12) A? for 2. In solution, and under forcing conditions, both compounds are extraordinarily unreactive towards hydroxide ions.

Full text of DOI:10.1016/j.jorganchem.2005.12.072

Journal of Organometallic Chemistry 691 (2006) 2593–2598
www.elsevier.com/locate/jorganchem
Note
The structurally characterised silyl complexes, Os(j2-S2CNMe2)-
(SiMeCl2)(CO)(PPh3)2 and Os(j2-S2CNMe2)(SiCl3)(CO)(PPh3)2,
which have remarkably unreactive Si–Cl bonds
*
*
Wai-Him Kwok, Guo-Liang Lu, Clifton E.F. Rickard, Warren R. Roper , L. James Wright
Department of Chemistry, The University of Auckland, Private Bag 92019, Auckland, New Zealand
Received 17 November 2005; received in revised form 12 December 2005; accepted 12 December 2005
Available online 20 March 2006
Abstract
Treatment of Os(j2-S2CNMe2)H(CO)(PPh3)2 with HSiMeCl2 or HSiCl3 gives in high yield Os(j2-S2CNMe2)(SiMeCl2)(CO)(PPh3)2
(1) or Os(j2-S2CNMe2)(SiCl3)(CO)(PPh3)2 (2), respectively. The crystal structures of both compounds have been determined and the
˚
˚
Os–Si distances are 2.3672(10) A for 1 and 2.3449(12) A for 2. In solution, and under forcing conditions, both compounds are extraor-
dinarily unreactive towards hydroxide ions.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Silyl complex; Osmium; X-ray crystal structure
1. Introduction
ligand also affects the reactivity, and the general trend is
that progressive chlorine replacement of organo-groups
on silicon reduces the reactivity of the Si–Cl bonds. An
example of this phenomenon is that when one of the chlo-
rides in the inert compound [CpFe(CO)2]2SiCl2 is replaced
by hydride to give [CpFe(CO)2]2SiHCl the remaining Si–Cl
bond is readily hydrolysed. Interestingly, structural data
suggests that both the Ru–Si and Si–Cl distances in
Cp(PR3)2RuSiX3 increase when chloride is replaced by
either methyl or phenyl [11]. The increased Si–Cl distances
have been attributed to d(Ru)–r*(Si–Cl) p-back-bonding
interactions and this may partly explain the increased
Si–Cl bond reactivity.
We have previously reported that the unsaturated, five-
coordinate, dimethylchlorosilyl complex, Os(SiMe2Cl)Cl-
(CO)(PPh3)2, is easily hydrolysed to Os(SiMe2OH)Cl-
(CO)(PPh3)2, [12] just as Os(SiCl3)Cl(CO)(PPh3)2 is easily
hydrolysed to Os[Si(OH)3]Cl(CO)(PPh3)2 [3]. On the other
hand, the saturated, six-coordinate, dimethylchlorosilyl
complex, Os(j2-S2CNMe2)(SiMe2Cl)(CO)(PPh3)2 [12], is
quite difficult to hydrolyse under base conditions but is
readily converted to Os(j2-S2CNMe2)(SiMe2OH)(CO)-
(PPh3)2 upon chromatography on silica gel. In this paper,
Metal complexes with chloro-substituted silyl ligands,
LnM–SiR3ꢀnCln (n = 1–3), are often useful substrates,
through nucleophilic substitution reactions, for the synthe-
ses of silyl complexes with interesting functionalisation at
silicon. Examples include the syntheses of compounds of
the type, LnM–SiR3ꢀnXn, where X can be H [1], R [2],
OH [3,4], OR [5], SR [6], NR2 [7], and F [2,8]. However,
the reactivity of the Si–Cl bonds in chlorosilyl ligands is
variable and in some exceptional cases the Si–Cl bonds
are quite unreactive towards hydrolysis. An example is pro-
vided by the ready hydrolysis of CpFe(CO)2SiR2Cl
whereas the corresponding ruthenium derivative, CpRu-
(CO)2SiR2Cl, is inert to hydrolysis [9]. A further example
is that two electron-rich CpFe(CO)2 fragments attached
to the one silicon atom in [CpFe(CO)2]2SiCl2 renders the
Si–Cl bonds unreactive to Cl/OH exchange [10]. Further-
more, the number of chloride substituents on the silyl
*
Corresponding authors. Tel.: +64 9 373 7999x8320; fax: +64 9 373
7422 (W.R. Roper).
E-mail address: w.roper@auckland.ac.nz (W.R. Roper).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.12.072

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W.-H. Kwok et al. / Journal of Organometallic Chemistry 691 (2006) 2593–2598
Table 1
we report that the preparative procedure used to make
Os(j2-S2CNMe2)(SiMe2Cl)(CO)(PPh3)2 is equally effective
for the preparation of the closely related chloro-silyl com-
plexes, Os(j2-S2CNMe2)(SiMeCl2)(CO)(PPh3)2 (1) and
Os(j2-S2CNMe2)(SiCl3)(CO)(PPh3)2 (2) and crystal struc-
tures for these two compounds are reported. However,
the main purpose of this note is to draw attention to the
remarkable lack of reactivity towards hydrolysis of the
Si–Cl bonds in the two saturated complexes 1 and 2.
Data collection and processing parameters for 1 and 2
1 Æ 2CH2Cl2
2 Æ 2CH2Cl2
Formula
C43H43Cl6NOOsP2S2Si C42H40Cl7NOOsP2S2Si
1146.83
Molecular weight
Crystal system
Space group
1167.25
Monoclinic
C2/m
28.0811(8)
15.0746(4)
11.4800(3)
Monoclinic
C2/m
28.0882(4)
15.1144(1)
11.4867(2)
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
96.797(1)
96.810(1)
2. Results and discussion
3
˚
V (A )
4842.25(11)
4
1.573
2280
3.17
4825.3(2)
4
1.607
2312
3.24
2.1. Syntheses and crystal structures of Os(j2-S2CNMe2)-
(SiMeCl2)(CO)(PPh3)2 (1) and Os(j2-S2CNMe2)-
(SiCl3)(CO)(PPh3)2 (2)
Z
D(calc) (g cmꢀ3
F(000)
)
l (mmꢀ1
)
Crystal size (mm)
2h (min–max) (ꢁ)
Reflections collected
Independent
0.34 · 0.18 · 0.10
1.46–27.51
14775
0.42 · 0.22 · 0.04
1.46–26.05
14285
As depicted in Scheme 1 the reaction between Os(j2-S2-
CNMe2)H(CO)(PPh3)2 and the two chlorosilanes,
HSiMeCl2 and HSiCl3 proceeds smoothly to give the
corresponding colourless osmium silyl complexes, Os(j2-
S2CNMe2)(SiMeCl2)(CO)(PPh3)2 (1) and Os(j2-S2CNMe2)-
(SiCl3)(CO)(PPh3)2 (2), respectively, in good yield. The IR
spectrum of 1 shows m(CO) at 1893(s), 1877 cmꢀ1, the
observation of two bands presumably arising from solid-
state splitting. The IR spectrum of 2 shows m(CO) at
1901(s) cmꢀ1, this higher value being expected and attribut-
able to the more electron-withdrawing SiCl3 group [2].
That the geometry of 1 and 2 is as drawn in Scheme 1 is
indicated by the presence of two signals for the methyl
groups of the dimethydithiocarbamate ligands (in both
the 1H and 13C NMR spectra) and the observation of a sin-
glet resonance in the 31P NMR spectra of these com-
pounds. Further spectroscopic data for these two
compounds is collected in Section 4 and requires no special
comment.
5565 [0.0215]
4938 [0.0265]
reflections [Rint
T (min–max)
]
0.411, 0.742
0.343, 0.881
1.065
Goodness-of-fit on F2 1.062
R (observed data)
R (all data)
R1 = 0.0276;
R1 = 0.0280;
wR2 = 0.0738
R1 = 0.0301;
wR2 = 0.0751
ꢀ1.58, 2.24
wR2 = 0.0721
R1 = 0.0296;
wR2 = 0.0734
ꢀ1.72, 1.37
Diff. map (min–max)
ꢀ3
˚
(e A
)
P
P
R = iFo| ꢀ |Fci/ |Fo|.
P
P
2
2
1=2
wR2 ¼ f ½wðF 2o ꢀ F c2Þ ꢁ= ½wðF 2oÞ ꢁg
.
and 2, respectively, and selected bond lengths and bond
angles are listed in Tables 2 and 3, respectively. The geom-
etries of both complexes are approximately octahedral with
the two triphenylphosphine ligands arranged mutually
trans. In both compounds the attachment of the bidentate
dimethyldithiocarbamate ligand is unsymmetrical, with the
Os–S distance greater when S is trans to the silyl ligand
The crystal structures of 1 and 2 were determined, the
crystal data and refinement details for both structures are
in Table 1, the molecular geometries are shown in Figs. 1
˚
˚
(2.5043(9) A for 1; 2.4968(11) A for 2) and less when S is
Scheme 1. Syntheses of Os(j2-S2CNMe2)(SiMeCl2)(CO)(PPh3)2 (1) and Os(j2-S2CNMe2)(SiCl3)(CO)(PPh3)2 (2).

W.-H. Kwok et al. / Journal of Organometallic Chemistry 691 (2006) 2593–2598
2595
Table 2
Selected bond lengths (A) and bond angles (ꢁ) for 1
˚
Bond lengths
Os–C(1)
Os–Si
Os–P(1)
Os–S(2)
Os–S(1)
Cl(1)–Si
Cl(2)–Si
C(5)–Si
1.855(4)
2.3672(10)
2.3948(7)
2.4553(10)
2.5043(9)
2.1252(14)
2.066(8)
1.93(3)
S(1)–C(2)
S(2)–C(2)
O–C(1)
1.718(4)
1.709(4)
1.159(5)
1.330(5)
N–C(2)
Bond angles
C(1)–Os–Si
C(1)–Os–P(1)
Si–Os–P(1)
P(1)–Os–P(1)#1
C(1)–Os–S(2)
Si–Os–S(2)
90.45(13)
89.84(2)
97.249(17)
165.50(3)
177.00(12)
86.56(3)
Fig. 1. Molecular geometry of Os(j2-S2CNMe2)(SiMeCl2)(CO)(PPh3)2
(1).
P(1)–Os–S(2)
C(1)–Os–S(1)
Si–Os–S(1)
P(1)–Os–S(1)
S(2)–Os–S(1)
O–C(1)–Os
90.533(17)
112.20(12)
157.35(4)
83.351(17)
70.80(3)
176.7(4)
Symmetry transformations used to generate equivalent atoms: (#1) x, ꢀy, z.
Table 3
˚
Selected bond lengths (A) and bond angles (ꢁ) for 2
Bond lengths
Os–C(1)
Os–Si
1.860(5)
2.3449(12)
2.4005(8)
2.4539(11)
2.4968(11)
2.1084(16)
2.0983(12)
1.723(5)
1.711(5)
1.163(6)
1.324(6)
1.460(7)
Os–P(1)
Os–S(2)
Os–S(1)
Cl(1)–Si
Cl(2)–Si
S(1)–C(2)
S(2)–C(2)
O–C(1)
N–C(2)
N–C(3)
N–C(4)
Fig. 2. Molecular geometry of Os(j2-S2CNMe2)(SiCl3)(CO)(PPh3)2 (2).
˚
˚
trans to the CO ligand (2.4553(10) A for 1; 2.4539(11) A for
2). This observation relates to the trans influence of the silyl
ligand and the distances suggest that the trans influence is
slightly greater for SiMeCl2 than for SiCl3. The Os–Si dis-
tance in Os(j2-S2CNMe2)(SiMeCl2)(CO)(PPh3)2 (1) is
1.471(7)
˚
2.3672(10) A, which is much less than the average (2.4499
Bond angles
C(1)–Os–Si
˚
with SD 0.0508 A) of 10 measured Os–Si distances
90.77(14)
89.82(2)
97.063(19)
165.87(4)
178.12(14)
87.35(4)
90.414(19)
110.96(14)
158.27(4)
83.474(19)
70.92(4)
C(1)–Os–P(1)
Si–Os–P(1)
P(1)#1–Os–P(1)
C(1)–Os–S(2)
Si–Os–S(2)
P(1)–Os–S(2)
C(1)–Os–S(1)
Si–Os–S(1)
P(1)–Os–S(1)
S(2)–Os–S(1)
Cl(2)#1–Si–Cl(2)
Cl(2)–Si–Cl(1)
Cl(2)–Si–Os
Cl(1)–Si–Os
recorded in the Cambridge Crystallographic Data Base
for octahedral osmium silyl complexes where silicon is
four-coordinate. It is also less than the corresponding value
for the related Os(j2-S2CNMe2)(SiMe2Cl)(CO)(PPh3)2 at
˚
˚
2.4021(11) A [12]. The Os–Si distance in 2 (2.3449(12) A)
is shorter than in either Os(j2-S2CNMe2)(SiMe2Cl)(CO)-
(PPh3)2 or 1, as would be expected for a trichlorosilyl
ligand [2]. The overall trend is that the Os–Si distance
decreases with increasing chloride substitution on silicon.
97.31(7)
˚
The Si–Cl distances are 2.1252(14) A for the non-
101.15(5)
116.96(4)
119.65(6)
˚
disordered chloride in 1 and 2.1084(16) and 2.0983(12) A
in 2. All of these are long when compared with the average
˚
˚
of recorded Si–Cl distances of 2.0579 A, SD 0.0435 A
Symmetry transformations used to generate equivalent atoms: (#1) x, ꢀy, z.

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W.-H. Kwok et al. / Journal of Organometallic Chemistry 691 (2006) 2593–2598
(Cambridge Crystallographic Data Base) but no convinc-
ing trends with respect to chloride substitution are
apparent.
qualitative observations of the relative reactivity of the
Si–Cl bonds in these complexes lead to the following
conclusions. The remarkable inertness of the trichlorosilyl
derivative 2, contrasts strongly with the ease of hydrolysis
of the coordinatively unsaturated trichlorosilyl complex,
Os(SiCl3)Cl(CO)(PPh3)2 and this difference must be attrib-
uted to the availability of a vacant coordination site at
osmium in Os(SiCl3)Cl(CO)(PPh3)2 which offers the oppor-
tunity for anion coordination at osmium, i.e., the anion
[Os(SiCl3)(OH)Cl(CO)(PPh3)2]ꢀ may be formed as a
prelude to hydrolysis. Hydrolysis could then become an
intramolecular ligand reaction. Support for this idea comes
from the fact that chloride ion coordinates to Os(SiCl3)Cl-
(CO)(PPh3)2 with formation of the colourless, coordin-
atively saturated anion, [Os(SiCl3)Cl2(CO)(PPh3)2]ꢀ. We
have isolated this anion as the dimethylammonium salt,
[NMe2H2][Os(SiCl3)Cl2(CO)(PPh3)2], and characterized it
by crystal structure determination [14]. Other related
osmium anions containing silyl ligands are also known,
e.g., [Os(SiMe3)(Me)2(CO)(PPh3)2]ꢀ [15]. There is also the
report of a ruthenium anion containing two trichlorosilyl
ligands, [PCy3H][Ru(SiCl3)2Cl(CO)(PCy3)] [16]. Within
the set of coordinatively saturated complexes, Os(j2-
S2CNMe2)(SiMe2Cl)(CO)(PPh3)2, Os(j2-S2CNMe2)(SiMe-
Cl2)(CO)(PPh3)2, and Os(j2-S2CNMe2)(SiCl3)(CO)(PPh3)2
it appears that the SiCl3 ligand is least reactive and the
SiMe2Cl ligand the most reactive.
2.2. Reactivity towards hydrolysis of compounds
Os(j2-S2CNMe2)(SiMe2Cl)(CO)(PPh3)2,
Os(j2-S2CNMe2)(SiMeCl2)(CO)(PPh3)2 (1), and
Os(j2-S2CNMe2)(SiCl3)(CO)(PPh3)2 (2)
We have previously reported all three of the five-coor-
dinate, coordinatively unsaturated derivatives, Os(Si-
Me2Cl)Cl(CO)(PPh3)2, Os(SiMeCl2)Cl(CO)(PPh3)2, and
Os(SiCl3)Cl(CO)(PPh3)2, are readily hydrolysed (KOH/
H2O/THF at room temperature within minutes) to the cor-
responding osmasilanols, Os[SiMe2(OH)]Cl(CO)(PPh3)2
[12], Os[SiMe(OH)2]Cl(CO)(PPh3)2 [13], and Os[Si(OH)3]-
Cl(CO)(PPh3)2 [2,3]. Replacement of the osmium-bound
chloride ligand in Os(SiMe2Cl)Cl(CO)(PPh3)2 by the
bidentate dimethyldithiocarbamate ligand to give Os(j2-
S2CNMe2)(SiMe2Cl)(CO)(PPh3)2 brings about a marked
change in the reactivity of the Si–Cl bond. Similar base
hydrolysis conditions to those given above are ineffective
for this six-coordinate, coordinatively saturated compound
and forcing conditions (KOH/H2O/THF at 60 ꢁC, 16 h)
produce Os(j2-S2CNMe2)[SiMe2(OH)](CO)(PPh3)2 (10%)
and Os(j2-S2CNMe2)[Si(OH)3](CO)(PPh3)2 (36%) [12] and
Os(j2-S2CNMe2)H (CO)(PPh3)2 (20%) (see Scheme 2).
Likewise, as shown in Scheme 2, vigorous base conditions
with Os(j2-S2CNMe2)(SiMeCl2)(CO)(PPh3)2 (1) return
unreacted 1 with small amounts of Os(j2-S2CNMe2)-
[Si(OH)3](CO)(PPh3)2. Significantly, no Os(j2-S2CNMe2)-
[SiMe(OH)2](CO)(PPh3)2 was isolated. Os(j2-S2CNMe2)-
(SiCl3)(CO)(PPh3)2 (2), when subjected to these same
forcing conditions for 24 h returned unreacted 2 only. These
3. Conclusions
It has been demonstrated that the two coordinatively
saturated chlorosilyl-complexes, Os(j2-S2CNMe2)(Si-
MeCl2)(CO)(PPh3)2 (1) and Os(j2-S2CNMe2)(SiCl3)(CO)-
Scheme 2. Reactivity towards hydrolysis of Os(j2-S2CNMe2)(SiMe2Cl)(CO)(PPh3)2, Os(j2-S2CNMe2)(SiMeCl2)(CO)(PPh3)2 (1), and Os(j2-S2CNMe2)-
(SiCl3)(CO)(PPh3)2 (2).

W.-H. Kwok et al. / Journal of Organometallic Chemistry 691 (2006) 2593–2598
2597
1
(PPh3)2 (2) are readily prepared from reaction between
Os(j2-S2CNMe2)H(CO)(PPh3)2 and the appropriate silane.
The most remarkable chemical feature of these molecules is
the inertness of the Si–Cl bonds, which resist hydrolysis
even under very forcing conditions. It is suggested that this
inertness is associated with the coordinative saturation of
the osmium centre since the closely related, coordinatively
unsaturated analogues, Os(SiMeCl2)Cl(CO)(PPh3)2 and
Os(SiCl3)Cl(CO)(PPh3)2 are easily hydrolysed, perhaps
because osmium offers an alternative site for hydroxide
attack and the ensuing hydrolysis then becomes
intramolecular.
m(CO). H NMR (CDCl3, d): 0.64 (s, 3H, Si(CH3)), 1.98
(s, 3H, N(CH3)2), 2.23 (s, 3H, N(CH3)2), 7.31–7.32 (m,
18H, PPh3), 7.71–7.74 (m, 12H, PPh3). 13C NMR (CDCl3,
d): 14.9 (Si(CH3)), 36.7, 36.8 (N(CH3)2), 127.1 (br, o-
C6H5), 129.5 (s, p-C6H5), 135.1 (br, m-C6H5), 186.6 (t,
2JCP = 11.6 Hz, CO), 208.4 (S2CNMe2). 31P NMR (CDCl3,
d): 7.27 (s).
4.3. Preparation of Os(j2-S2CNMe2)(SiCl3)(CO)(PPh3)2
(2)
Os(j2-S2CNMe2)H(CO)(PPh3)2 (0.086 g, 0.10 mmol)
was placed in a 250 mL Schlenk tube and toluene (5 mL)
and HSiCl3 (0.200 mL, 2.0 mmol) added. The tube was
sealed, cooled in liquid nitrogen and then evacuated. After
warming to ambient temperature, the sealed tube was
shielded with a safety shield (Caution. Pressure increases
as reaction proceeds) and heated in an oil bath at 100 ꢁC
for 12 h. During this time the yellow solution turned to a
paler yellow colour. After cooling, the solvent volume
was reduced under vacuum and hexane added slowly to
induce crystallisation of a colourless solid. This was col-
lected and recrystallised from dry dichloromethane–etha-
nol to give pure 2 (0.094 g, 94%). Anal. Calc. for
C40H36Cl3NOOsP2S2Si: C, 48.17; H, 3.64; N, 1.38. Found:
4. Experimental
4.1. General procedures and instruments
Standard laboratory procedures were followed as have
been described previously [17]. The compound Os(j2-
S2CNMe2)H(CO)(PPh3)2 [18] was prepared by the litera-
ture method.
Infrared spectra (4000–400 cmꢀ1) were recorded as
Nujol mulls between KBr plates on a Perkin–Elmer Para-
gon 1000 spectrometer. NMR spectra were obtained on
either a Bruker DRX 400 or a Bruker Avance 300 at
25 ꢁC. For the Bruker DRX 400, H, 13C, and 31P NMR
C, 48.06; H, 3.86; N, 1.60%. IR (cmꢀ1): 1901(s) m(CO). H
1
1
spectra were obtained operating at 400.1 (1H), 100.6
(13C), and 162.0 (31P) MHz, respectively. For the Bruker
NMR (CDCl3, d): 1.99 (s, 3H, N(CH3)2), 2.24 (s, 3H,
N(CH3)2), 7.32–7.34 (m, 18H, PPh3), 7.70–7.74 (m, 12H,
PPh3). 13C NMR (CDCl3, d): 36.6, 36.7 (N(CH3)2), 127.3
(br, o-C6H5), 129.7 (s, p-C6H5), 135.1 (br, m-C6H5), 184.9
(br, CO), 208.0 (S2CNMe2). 31P NMR (CDCl3, d): 6.72 (s).
1
Avance 300, H, 13C, and 31P NMR spectra were obtained
operating at 300.13 (1H), 75.48 (13C), and 121.50 (31P)
MHz, respectively. Resonances are quoted in ppm and
1H NMR spectra referenced to either tetramethylsilane
(0.00 ppm) or the proteo-impurity in the solvent
(7.25 ppm for CHCl3). 13C NMR spectra were referenced
to CDCl3 (77.00 ppm), and 31P NMR spectra to 85%
orthophosphoric acid (0.00 ppm) as an external standard.
Elemental analyses were obtained from the Microanalytical
Laboratory, University of Otago.
4.4. X-ray crystal structure determinations for complexes 1
and 2
X-ray data collection was by Siemens SMART diffrac-
tometer with a CCD area detector using graphite mono-
chromated Mo Ka radiation (k = 0.71073 A) at 150 K.
˚
Data were integrated and corrected for Lorentz and
polarisation effects using SAINT [19]. Semi-empirical
absorption corrections were applied based on equivalent
reflections using SADABS [20]. The structures were solved
by Patterson and Fourier methods and refined by full-
matrix least-squares on F2 using programs SHELXS [21]
and SHELXL [22]. All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were located geometri-
cally and refined using a riding model. The two structures
are isostructural and both contain residual electron den-
sity which could not be assigned to ordered solvent mol-
ecules. In both cases the residual density has been treated
as disordered solvent and removed with the Squeeze
function of PLATON [23] before the final refinement. For
1 there is disorder between one chlorine atom and the
methyl group of the dichloromethylsilyl ligand. This dis-
order has been modeled with half-weighted atoms. Crys-
tal data and refinement details for 1 and 2 are given in
Table 1.
4.2. Preparation of Os(j2-S2CNMe2)-
(SiMeCl2)(CO)(PPh3)2 (1)
Os(j2-S2CNMe2)H(CO)(PPh3)2 (0.150 g, 0.17 mmol)
was placed in a 250 mL Schlenk tube and toluene
(10 mL) and HSiMeCl2 (0.300 g, 2.55 mmol) added. The
tube was sealed, cooled in liquid nitrogen and then evacu-
ated. After warming to ambient temperature, the sealed
tube was shielded with a safety shield (Caution. Pressure
increases as reaction proceeds) and heated in an oil bath
at 90 ꢁC for 1 h. During this time the yellow solution
turned to a paler yellow colour. After cooling, the solvent
volume was reduced under vacuum and hexane added
slowly to induce crystallisation of a colourless solid. This
was collected and recrystallised from dry dichlorometh-
ane–hexane to give pure 1 (0.116 g, 70%). Anal. Calc. for
C41H39NOCl2SiP2OsS2: C, 50.40; H, 4.02; N, 1.43. Found:
C, 50.29; H, 3.82; N, 1.40%. IR (cmꢀ1): 1893(s), 1877

2598
W.-H. Kwok et al. / Journal of Organometallic Chemistry 691 (2006) 2593–2598
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Crystallographic data (excluding structure factors) for
the structures reported have been deposited with the
Cambridge Crystallographic Data Centre as Supplementary
Publication Nos. 288557 and 288558 for 1 and 2, respec-
tively. Copies of this information can be obtained free of
charge from the Director, CCDC, 12 Union Road, Cam-
bridge, CB2 1EZ, UK (fax: +44 1223 336 033; e-mail: depos-
it@ccdc.cam.ac.uk or www: http://www.ccdc.cam. ac.uk).
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Acknowledgements
We thank the Marsden Fund administered by the Royal
Society of NZ for supporting this work. We also thank the
Croucher Foundation, Hong Kong, for support and for
granting a Postdoctoral Fellowship to H.-W.K. We also
thank the University of Auckland Research Committee
for partial support of this work through Grants-in-Aid.
[17] S.M. Maddock, C.E.F. Rickard, W.R. Roper, L.J. Wright, Organo-
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