The synthesis, structure, and reactivity of the osmium(IV) trihydrido silyl complex, OsH3(SiMe3)(CO)(PPh3)2

Article abstract of DOI:10.1016/S0022-328X(99)00617-8

Reaction between the five coordinate complex, Os(Ph)Cl(CO)(PPh₃)₂, and HSiMe₃ produces the osmium(IV) trihydrido silyl complex, OsH₃(SiMe₃)(CO)(PPh₃)₂ (1). The structure of 1 has been determined by single crystal X-ray crystallography and by multi-nuclear NMR spectroscopy. The structure has an approximately tetrahedral disposition of silyl, carbonyl and the two PPh₃ ligands about osmium with the three classical hydride ligands located, one trans to CO, and the other two each approximately trans to a PPh₃. Treatment of complex 1 with HSiR₃ (R=Et, Ph), HSn(p-tolyl)₃, or HC₂Ph gives OsH₃(SiR₃)(CO)(PPh₃)₂ (R=Et (2), Ph (3)), OsH₂[Sn(p-tolyl)₃]₂(CO)(PPh₃)₂ (4) or OsH(C₂Ph)(CO)(PPh₃)₃ (5), respectively. A likely intermediate in these reactions is the coordinatively unsaturated complex, OsH₂(CO)(PPh₃)₂.

Full text of DOI:10.1016/S0022-328X(99)00617-8

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 593–594 (2000) 458–464
The synthesis, structure, and reactivity of the osmium(IV)
trihydrido silyl complex, OsH3(SiMe3)(CO)(PPh3)2
Michael Mo¨hlen, Clifton E.F. Rickard, Warren R. Roper *, David M. Salter,
L. James Wright 1
Department of Chemistry, The Uni6ersity of Auckland, Pri6ate Bag 92019, Auckland, New Zealand
Received 12 August 1999; accepted 18 October 1999
Dedicated to Professor Fausto Calderazzo on the occasion of his 70th birthday.
Abstract
Reaction between the five coordinate complex, Os(Ph)Cl(CO)(PPh3)2, and HSiMe3 produces the osmium(IV) trihydrido silyl
complex, OsH3(SiMe3)(CO)(PPh3)2 (1). The structure of 1 has been determined by single crystal X-ray crystallography and by
multi-nuclear NMR spectroscopy. The structure has an approximately tetrahedral disposition of silyl, carbonyl and the two PPh3
ligands about osmium with the three classical hydride ligands located, one trans to CO, and the other two each approximately
trans to a PPh3. Treatment of complex 1 with HSiR3 (R=Et, Ph), HSn(p-tolyl)3, or HC2Ph gives OsH3(SiR3)(CO)(PPh3)2 (R=Et
(2), Ph (3)), OsH2[Sn(p-tolyl)3]2(CO)(PPh3)2 (4) or OsH(C2Ph)(CO)(PPh3)3 (5), respectively. A likely intermediate in these reactions
is the coordinatively unsaturated complex, OsH2(CO)(PPh3)2. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Hydride complexes; Silyl complexes; Osmium
1. Introduction
reported recently by Esteruelas and co-workers [4].
These compounds were prepared by treatment of either
OsH2(h2-CH2ꢀCHEt)(CO)(PiPr3)2 or OsH(h2-H2BH2)-
(CO)(PiPr3)2 with the appropriate silane. Subsequently,
we have described the synthesis and characterisation of
the seven co-ordinate osmium trihydrido silyl com-
plexes, OsH3(SiR3)(PPh3)3 (R=Pyr, Et, Ph; Pyr=1-
NC4H4), which were isolated after heating OsH4(PPh3)3
and the appropriate silane in benzene [5]. The
analogous ruthenium complex, RuH3(SiPyr3)(PPh3)3
was prepared in a similar manner. Several other ruthe-
nium trihydrido silyl complexes of the type
RuH3(SiR3)Ln have also been characterised, having ei-
ther alkyl [6,7], aryl [7,8], alkoxy [7,8], or halogen [8]
substituents on the silicon. Examples of iron trihydrido
silyl complexes include the series of complexes
FeH3(SiR3)(PR3)3 and FeH3(SiR3)(CO)(dppe) (dppe=
Ph2CH2CH2PPh2) [9,10].
Polyhydrido, silyl-containing transition metal com-
plexes are postulated as intermediate species in reac-
tions involving the oxidative addition of silanes to
transition metal hydride compounds [1]. These com-
plexes are often not isolated, but instead lose dihydro-
gen to afford transition metal silyl products [1,2]. As a
consequence, relatively few polyhydrido transition
metal silyl complexes have been characterised. Investi-
gating the reactivity of complexes of this type may
provide a better understanding of the role such com-
plexes play in important industrial processes such as
transition metal catalysed hydrosilation reactions [3].
The syntheses and characterisations of the first os-
mium trihydrido silyl complexes, OsH3(SiR3)-
(CO)(PiPr3)2 (SiR3=SiPh2H, SiPh3, SiPh(OMe)2), were
In this paper we describe the synthesis, structural and
spectroscopic characterisation, and some reactions of
the osmium(IV) trihydrido, silyl complex, OsH3-
(SiMe3)(CO)(PPh3)2 (1).
* Corresponding author. Tel.: +64-9-3737999; ext. 8320; fax: +
64-9-3737422.
E-mail address: w.roper@auckland.ac.nz (W.R. Roper)
1 Also corresponding author.
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00617-8

M. Mo¨hlen et al. / Journal of Organometallic Chemistry 593–594 (2000) 458–464
459
2. Results and discussion
2.1. Synthesis and spectroscopic characterisation of
OsH3(SiMe3)(CO)(PPh3)2 (1)
Treatment of a solution of Os(Ph)Cl(CO)(PPh3)2
with HSiMe3 for 18 h at room temperature gives
OsH3(SiMe3)(CO)(PPh3)2 (1) in 70% isolated yield (see
Scheme 1). This unexpected product contrasts with the
compounds derived from the reactions between
Os(Ph)Cl(CO)(PPh3)2 and chlorosilanes. These are the
co-ordinatively unsaturated osmium silyl complexes,
Scheme 1. Synthesis and reactions of OsH3(SiMe3)(CO)(PPh3)2 (1).
Os(SiR3)Cl(CO)(PPh3)2
SiClMe2), which have been reported previously [11].
Furthermore, the ruthenium analogue of
(SiR3ꢀSiCl3,
SiCl2Me,
Os(Ph)Cl(CO)(PPh3)2 gives the Ru(II) trimethylsilyl
complex Ru(SiMe3)Cl(CO)(PPh3)2, on treatment with
HSiMe3 [12,13].
The crystal structure of 1 (see details below) confirms
the geometry shown in Scheme 1 and the following
discussion of the NMR spectra of 1 is made on the
1
basis of this geometry. At 300 K the H-NMR spec-
trum of 1 shows the expected resonances for the
trimethylsilyl and triphenylphosphine groups, as well as
a broad resonance centred at −9.0 ppm due to the
three hydride ligands. The 31P{1H}-NMR spectrum (at
213 K) displays a single slightly broadened signal, at
13.43 ppm, for the two PPh3 ligands.
Fig. 1. Experimental (213 K) and simulated 1H-NMR hydride reso-
nances of OsH3(SiMe3)(CO)(PPh3)2 (1).
In the 1H-NMR spectrum at 213 K, the hydride
resonance resolves to a pattern expected for the
AA%BXX% spin system (see Fig. 1). The signal at −8.82
ppm is immediately recognisable as a triplet of triplets
2
(2JHP=19.4 Hz; JHH%=3.4 Hz) and is assigned to the
unique hydride trans to the CO ligand. The signal at
−9.20 ppm, which has twice the integral of the signal
at −8.82 ppm, appears as a complex multiplet. Using
an NMR simulation/iteration program, together with
the coupling constants derived above, the remaining
coupling constants were obtained. These are given in
Fig. 2 along with the nuclei numbering scheme that was
used. The 31P-NMR spectrum, which was proton-de-
coupled selectively in the aromatic region only, gave a
complex multiplet that could be simulated by using the
HP and PP% coupling constants derived above. Differ-
ences between the spectra discussed here for 1 and
those reported for the complexes OsH3(SiPh2H)-
(CO)(PiPr3)2 [4], and RuH3(SiPh2H)(CO)(PtBu2Me)2
[14] can be attributed to different geometries in these
latter two compounds because of the very bulky phos-
phine ligands.
Fig. 2. Coupling constants and nuclei numbering scheme for
OsH3(SiMe3)(CO)(PPh3)2 (1).
[16], and therefore it is unlikely that there is any
significant SiꢁH interaction in OsH3(SiMe3)(CO)-
(PPh3)2.
1
The H-NMR signal at 213 K of the single hydride
2
1
trans to CO, has a J(HP) value of 19.4 Hz, which is
The T1 values for the H-NMR resonances of the
2
similar to the J(HPcis) values found in the complexes
hydrides in complex (1) were determined. The T1(min)
for the resonance of the hydride trans to CO occurs
close to 223 K and is 309 ms. A T1(min) was not
located for the other hydrides, however, at all tempera-
OsH(SiR3)(CO)2(PPh3)2 (R3=Et3, Ph3, Ph2H) [15]. A
2
smaller J(HP) value would be expected if this hydro-
gen was involved in a M(h2-HSiR3) bonding interaction

460
M. Mo¨hlen et al. / Journal of Organometallic Chemistry 593–594 (2000) 458–464
Table 1
lar geometry is depicted in Fig. 3. The non-hydrogen
donor atoms are arranged in an approximately tetrahe-
dral manner about osmium and representative bond
lengths and bond angles are presented in Table 2. The
SiꢁOsꢁCO angle is 108.16(9)°, and the SiꢁOsꢁP angles
are 124.97(2) and 119.41(2)°. Surprisingly, the angle
between the two quite bulky triphenylphosphine ligands
is only 99.85(2)°. Two phenyl rings, one from each
triphenylphosphine, make a close face-to-face ap-
proach. In contrast, the P1ꢁOsꢁP2 angle between the
very bulky PiPr3 ligands in OsH3(SiHPh2)(CO)(PiPr3)2
is 146.06° [4]. The skeletal geometry suggests that the
hydride ligands should be located between the
trimethylsilyl group and the CO and two PPh3 ligands.
Indeed this is where the crystal structure revealed the
hydrides to be. A convenient description of their posi-
tions is as trans to CO, and approximately trans to each
of the two PPh3 ligands. The position of the hydride
trans to CO was determined more precisely than the
positions of the other two. The OsꢁSi bond length is
Crystal data and structure refinement for 1
Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system
Space group
C40H42OOsP2Si
818.97
203(2)
0.71073
Monoclinic
P21/n
,
Unit cell dimensions
,
a (A)
9.929
23.2622(3)
16.0141(2)
103.0840(10)
3602.83(6)
4
1.510
3.691
1640
0.32×0.12×0.10
1.75–27.49
22333
7944 [Rint=0.0246]
6885
0.7091–0.3846
Full-matrix least-squares on F2
1.014
R1=0.0223, wR2=0.0496
R1=0.0303, wR2=0.0526
,
b (A)
,
c (A)
i (°)
3
,
Volume (A )
Z
Dcalc. (g cm−3
)
Absorption coefficient (mm−1
F(000)
)
Crystal size (mm)
q range for data collection (°)
Reflections collected
Unique reflections
Observed reflections [I\2|(I)]
Max. and min. transmission
Refinement method
,
2.4533(8)
A,
similar
to
that
found
in
OsH3(SiHPh2)(CO)(PiPr3)2 of 2.448 (2) A [4], and
falling at the longer end of the range of observed
osmiumꢁsilicon bond distances [15]. The SiꢁC(methyl)
bonds are the same within estimated S.D.s and the
CꢁSiꢁC angles are all uniform at approx. 105°. The
OsꢁSiꢁC angles are also very similar (between 112.0(1)
and 114.2(1)°) implying that the SiMe3 group is sym-
metrically bonded to the metal centre in
OsH3(SiMe3)(CO)(PPh3)2.
,
Goodness-of-fit on F2
R indices [I\2|(I)]
R indices (all data)
Largest difference peak and hole 0.870 and −0.655
−3
,
(e A
)
Table 2
,
Selected bond lengths (A) and angles (°) for 1
Bond lengths
OsꢁC
1.893(3)
2.3820(7)
2.3900(7)
2.4533(8)
1.58(9)
OsꢁP(2)
OsꢁP(1)
OsꢁSi
OsꢁH(1)
OsꢁH(2)
OsꢁH(3)
SiꢁC(2)
SiꢁC(1)
SiꢁC(3)
OꢁC
1.55(9)
1.45(10)
1.879(3)
1.881(3)
1.884(3)
1.155(3)
Fig. 3. Molecular geometry of OsH3(SiMe3)(CO)(PPh3)2 (1).
tures, the determined T1 values for both signals ranged
from 300 to 537 ms. This strongly implies that both
resonances originate from classical terminal hydride
ligands [17].
Bond angles
CꢁOsꢁP(2)
CꢁOsꢁP(1)
P(2)ꢁOsꢁP(1)
CꢁOsꢁSi
P(2)ꢁOsꢁSi
P(1)ꢁOsꢁSi
CꢁOsꢁH(1)
P(2)ꢁOsꢁH(3)
P(1)ꢁOsꢁH(2)
97.36(8)
103.21(8)
99.85(2)
108.16(9)
124.97(2)
119.41(2)
169(1)
2.2. Crystallographic study of
OsH3(SiMe3)(CO)(PPh3)2 (1)
173(1)
171(1)
The structure of 1 was obtained by an X-ray crystal
structure determination (see Table 1), and the molecu-

M. Mo¨hlen et al. / Journal of Organometallic Chemistry 593–594 (2000) 458–464
461
2.3. Reactions of OsH3(SiMe3)(CO)(PPh3)2 (1) with
Lewis Bases L (L=CO, CNp-tolyl, PPh3), HSiR3
(R=Et, Ph), HSn(p-tolyl)3, and phenylacetylene
reaction. OsH2[Sn(p-tolyl)3]2(CO)(PPh3)2 (4) was iso-
lated as a stable, colourless solid. The equivalence of
the stannyl ligands is revealed by the observation of a
1
single methyl resonance in the H-NMR spectrum at
In solution, OsH3(SiMe3)(CO)(PPh3)2 appears to re-
act via loss of HSiMe3 to form the highly reactive,
coordinatively unsaturated species, OsH2(CO)(PPh3)2
which then undergoes reaction with another ligand or
addition reactions with suitable HꢁSi, HꢁSn, and HꢁC
bonds.
Addition of the Lewis bases, L, to solutions of
complex 1 in toluene resulted in the formation of the
known compounds OsH2(CO)L(PPh3)2 (L=CO, CNp-
tolyl, PPh3). The addition of CO at 400 kPa for 2 h at
room temperature generated OsH2(CO)2(PPh3)2. Addi-
tion of CN(p-tolyl) formed OsH2(CO)(CNp-
tolyl)(PPh3)2 and OsH2(CO)(PPh3)3 was isolated after
heating a solution containing 1 and PPh3 in toluene at
ca. 50°C for 0.5 h. A similar reactivity pattern has been
observed for the ruthenium (IV) trihydrido, silyl com-
plexes, RuH3(SiR3)(PPh3)3 [8].
Heating solutions of OsH3(SiMe3)(CO)(PPh3)2 (1) in
the presence of excess triethylsilane resulted in the
formation of OsH3(SiEt3)(CO)(PPh3)2 (2), which was
isolated as a colourless crystalline solid. The methyl and
methylene resonances of the ethyl groups appear in the
1H-NMR spectrum of 2 as overlapping triplet and
quartet signals. At 298 K, resonances for the hydride
ligands occur as two broad signals at −8.92 and
−9.82 ppm. At 263 K, the signals resolve into patterns
closely resembling the low temperature hydride reso-
nances of complex 1, suggesting a similar structure. A
triplet of triplets at −9.04 ppm (2J(HP)=19.3 Hz;
2J(HH%)=3.6 Hz) was assigned to the unique hydride
ligand trans to CO. The other two hydride ligands give
a complex signal at −9.85 ppm, having the same
appearance as signal assigned to the other two hydrides
in OsH3(SiMe3)(CO)(PPh3)2. Again, the hydrides were
designated as classical hydride ligands, based on T1
measurements (see Section 3). Heating complex 2 in the
presence of excess HSiMe3 returned OsH3(SiMe3)(CO)-
(PPh3)2 (1).
Similarly, OsH3(SiPh3)(CO)(PPh3)2 (3) was synthe-
sised by reacting complex 1 with HSiPh3. A broad
resonance for the hydride ligands at −9.01 ppm in the
1H-NMR spectrum of complex 3 at 298 K, separates
into two signals at 233 K, one at −8.09 (triplet,
2J(HP)=20.0 Hz) and the other at −9.32 ppm (multi-
plet). The splitting pattern was very similar to that
observed for complex 1 at 213 K indicating again a
similar structure.
2.28 ppm, and also by only one set of p-tolyl signals in
the 13C-NMR spectrum. In contrast, two sets of signals
for the carbon atoms of the phenyl groups are ob-
served, indicating that the PPh3 ligands are inequiva-
lent. Consistent with this, the carbonyl signal in the
13C-NMR spectrum appears as a doublet of doublets
(2J(CP)=75.4 Hz; 2J(CP%)=10.8 Hz). The coupling
constant values suggest that the carbonyl ligand is
positioned approximately trans to one PPh3 ligand and
cis to the other. Inequivalent PPh3 ligands are identified
by two doublets at 1.36 and −6.84 ppm (2J(PP%)=26.5
Hz) in the 31P-NMR spectrum. A broad signal at
1
−7.67 ppm in the H-NMR spectrum of complex (4)
indicates that the hydride ligands are involved in a
dynamic process at 298 K. At 223 K, this signal re-
solves into two signals, each of which appears as a
doublet of doublets of doublets, centred at −6.98 and
−8.26 ppm. T1 values (223 K, 200 MHz) for each of
these signals of 231 and 219 ms, verify that terminal
hydride ligands are present. On the basis of the above
data, complex 4 appears to be very similar to the
trimethylstannyl analogue, OsH2(SnMe3)2(CO)(PPh3)2,
which has been previously reported [15]. It is not possi-
ble to propose a definitive structure for 4 based on the
above NMR data alone.
When OsH3(SiMe3)(CO)(PPh3)2 was treated with
phenylacetylene the product was characterised as
OsH(C2Ph)(CO)(PPh3)3 (5). Initial reactions gave only
small amounts of this product, but almost quantitative
yields of 5 could be achieved by the addition of further
PPh3 to the reaction mixture after an initial period of
heating. In the IR spectrum, a strong w(CO) band is
observed at 1931 cm−1 and a medium intensity band at
2091 cm−1 is assigned as w(CꢂC). A weaker, broader
band at 2078 cm−1, appearing as a shoulder of w(CꢂC),
is most likely w(OsꢁH). The presence of the hydride
ligand is clearly seen in the 1H-NMR spectrum of
complex 5 as a doublet of triplets centred at −8.49
ppm which integrates for one proton. The splitting
pattern is consistent with a geometry where the hydride
ligand is trans to one triphenylphosphine ligand and cis
to the remaining two equivalent PPh3 ligands. The
remaining acetylide and carbonyl ligands must there-
fore be positioned mutually trans.
The formation of complex 5 most likely involves
oxidative addition of HC2Ph to OsH2(CO)(PPh3)2 fol-
lowed by reductive elimination of dihydrogen to gener-
ate the coordinatively unsaturated complex OsH(C2-
Ph)(CO)(PPh3)2. This complex could not be isolated,
however, addition of PPh3 forms the stable coordina-
tively saturated product OsH(C2Ph)(CO)(PPh3)3 (5) in
good yield.
The reaction between OsH3(SiMe3)(CO)(PPh3)2 and
HSn(p-tolyl)3 yielded OsH2[Sn(p-tolyl)3]2(CO)(PPh3)2
(4). This reaction most likely proceeded through succes-
sive oxidative additions of HꢁSn bonds. Two equiva-
lents of HSn(p-tolyl)3 were required for complete

462
M. Mo¨hlen et al. / Journal of Organometallic Chemistry 593–594 (2000) 458–464
In conclusion, we have demonstrated that the simple
3.2. OsH3(SiMe3)(CO)(PPh3)2 (1)
and easily accessible osmium(IV) trihydrido, silyl com-
plex, OsH3(SiMe3)(CO)(PPh3)2, has a structure closely
similar to that of the OsH3(SiR3)(PPh3)3 family of
compounds [5], with CO replacing one triphenylphos-
phine ligand but with the positions of the remaining
ligands substantially unchanged. Furthermore, in con-
trast to OsH3(SiR3)(PPh3)3, OsH3(SiMe3)(CO)(PPh3)2
has a marked tendency to lose silane in solution and is
therefore a useful precursor to the reactive, coordina-
tively unsaturated, intermediate, OsH2(CO)(PPh3)2.
HSiMe3 was vigorously bubbled for ca. 20 s through
a solution of Os(Ph)Cl(CO)(PPh3)2 (0.200g; 0.23 mmol)
dissolved in toluene (10 ml) and contained in a Schlenk
tube. The Schlenk tube with the atmosphere of HSiMe3
still above the toluene solution was then sealed and the
solution stirred at room temperature for 18 h. The
resulting clear, orange solution was reduced in volume
to ca. 3 ml in vacuo and dry hexane (ca. 20 ml) added
to precipitate (1) as a cream solid. This solid was
collected by filtration and washed with several small
portions
of
hexane.
Recrystallization
from
dichloromethane–ethanol yielded large, off-white crys-
tals of (1) (0.134 g, 70%). m.p. 133–135°C. Anal. Calc.
for C40H42OOsP2Si: C, 58.66; H, 5.17. Found: C, 58.83;
H, 5.00. IR (cm−1): 1983s (CO); 2054w, 2033w, 1888s
(OsH). 1H-NMR (CDCl3; l): 7.40–7.12 (m, 30H,
PPh3); 0.51 (s, 9H, Si(CH3)3); −9.03 (broad, 3H,
3. Experimental
3.1. General procedures and instruments
Solvents were freshly distilled from appropriate dry-
ing agents prior to use [18]. Schlenk tubes with Teflon
screw caps were used as reaction vessels. Reactions
were carried out under an inert atmosphere of oxygen-
free nitrogen or sealed under vacuum (once the con-
tents had been frozen) when heating was involved.
Schlenk tubes were partly immersed in hot oil baths for
those reactions requiring heating. Reactions carried out
at room temperature were in the range 18–22°C. Crys-
tallizations were achieved in the reaction vessel by
removing most of the solvent by reduced pressure then
slowly adding another solvent in which the compound
is insoluble. Once the solid had formed, the tube was
opened and the compound collected in a glass sinter.
Recrystallization was accomplished in most cases by
dissolving the sample in a low boiling point solvent,
then adding an equivalent amount of a higher boiling
point solvent, in which the compound is insoluble. Slow
evaporation at reduced pressure was performed using a
rotary evaporator resulted in gradual crystallisation.
The compounds Os(Ph)Cl(CO)(PPh3)2 and HSiMe3
were prepared according to literature methods [19,20].
Infrared spectra (4000–400 cm−1) were recorded on
a Digilab FTS-7 infrared spectrometer as Nujol mulls
2
OsH3). 13C-NMR (CDCl3; l): 186.9 (t, CO, JCP=9.4
Hz); 138.0 (t%, PPh3 ipso, 1,3JCP=52 Hz) (the meaning
of t% and m,nJ are described in Ref. [13]); 133.8 (t%, PPh3
meta, 3,5JCP=11.8 Hz); 129.2 (s, PPh3 para); 127.6 (t%,
PPh3 ortho, 2,4JCP=9.2 Hz); 1.35 (s, Si(CH3)3). 31P-
NMR (CH2Cl2/CDCl3; l): 13.43 (s, broad). Determina-
tion of the T1 values for the hydride resonances of 1
were carried out by an inversion recovery NMR exper-
iment at 400 MHz. Values for temperature (°C), chem-
ical shift (ppm), T1 (ms) are: −40.0, −8.82, 334;
−40.0, −9.26, 385; −50, −8.84, 309; −50, −9.26,
412; −60, −8.87, 330; −60, −9.26, 460; −75, −
8.91, 415; −75, −9.27, 537.
3.3. OsH3(SiEt3)(CO)(PPh3)2 (2)
OsH3(SiMe3)(CO)(PPh3)2 (0.200 g; 0.24 mmol) and
HSiEt3 (0.160 g; 1.38 mmol) were heated in toluene (15
ml) in a sealed Schlenk tube at 55°C for 2 h. The
volume of the solution was reduced in vacuo to a small
volume (ca. 3 ml) and then dry hexane added to
precipitate (2). Recrystallization using dichloro-
methane–ethanol afforded colourless crystals of (2)
(0.096 g, 46%). m.p. 138–140°C. Anal. Calc. for
C43H48OOsP2Si: C, 59.98; H, 5.62. Found: C, 60.02; H,
5.56. IR (cm−1): 1983s (CO); 2050w, 1892s (OsH).
1H-NMR (CDCl3; l): 7.65–7.10 (m, 30H, PPh3); 0.70
(overlapping t and q, 15H, Si(CH2CH3)3); −8.92
(broad, ca. 1H, OsH); −9.81 (broad, 2H, OsH2). 13C-
1
between KBr plates. H-NMR spectra were recorded
on a Bruker AM-400 or DRX-400 instrument operating
at 400 MHz. Resonances are quoted in ppm and refer-
enced to either tetramethylsilane (0.00 ppm) or the
proteo-impurity in the solvent (7.25 ppm for CHCl3).
13C- and 31P-NMR spectra were obtained with a Bruker
AM-400 or DRX-400 instrument operating at 100.6
(13C) and 162.0 (31P) MHz, respectively. 13C-NMR
spectra were referenced to CDCl3 (77.00 ppm) and
31P-NMR to 85% orthophosphoric acid (0.00 ppm) as
an external standard. Melting points (uncorrected) were
determined on a Reichert hot stage microscope. Ele-
mental analyses were obtained from the Microanalyti-
cal Laboratory, University of Otago.
2
NMR (CDCl3; l): 187.3 (t, CO, JCP=5 Hz); 137.7 (t%,
PPh3 ipso, 1,3JCP=47.0 Hz); 133.8 (t%, PPh3 meta,
3,5JCP=11.2 Hz); 129.1 (s, PPh3 para); 127.5 (t%, PPh3
ortho, 2,4JCP=9.0 Hz); 16.02 (s, Si(CH2CH3)3); 8.71 (s,
Si(CH2CH3)3). 31P-NMR (CH2Cl2/CDCl3; l): 12.76 (s,
broad). Determination of the T1 values for the hydride
resonances of 2 were carried out by an inversion recov-
ery NMR experiment at 400 MHz. Values for tempera-

M. Mo¨hlen et al. / Journal of Organometallic Chemistry 593–594 (2000) 458–464
463
ture (°C), chemical shift (ppm), T1 (ms) are: −30,
−8.08, 258; −30, −9.29, 381; −40, −8.09, 273;
−40, −9.32, 372; −50, −8.11, 316; −50, −9.33,
439; −60, −8.12, 357; −60, −9.36, 497.
PPh3 ortho, 2,4JCP=19.6 Hz); 21.4 (s, Sn(C6H4CH3)3).
2
31P-NMR (CH2Cl2/CDCl3; l): 1.36 (d, JPP=26.5 Hz);
−6.84 (d, 2JPP=26.5 Hz). Determination of the T1
values for the hydride resonances of 4 were carried out
by an inversion recovery NMR experiment at 400
MHz. Values for temperature (°C), chemical shift
(ppm), T1 (ms) are: −30, −6.91, 184; −30, −8.20,
196; −40, −6.92, 207; −40, −8.22, 195; −50, −
6.98, 231; −50, −8.26, 219.
3.4. OsH3(SiPh3)(CO)(PPh3)2 (3)
OsH3(SiMe3)(CO)(PPh3)2 (0.200 g; 0.24 mmol) and
HSiPh3 (0.317 g; 1.22 mmol) were heated in toluene (15
ml) under a nitrogen atmosphere at 55°C for 3 h. The
volume of the solution was reduced in vacuo to a small
volume (ca. 3 ml) and then dry hexane added to
precipitate (3). Recrystallization using dichloro-
methane–ethanol afforded colourless crystals of (3)
(0.145 g, 59%). m.p. 169–172°C. Anal. Calc. for
C55H48OOsP2Si: C, 65.72; H, 4.81. Found: C, 65.44; H,
5.05. IR (cm−1): 1987s (CO); 2071w, 2016w, 1900s
3.6. OsH(C2Ph)(CO)(PPh3)3 (5)
OsH3(SiMe3)(CO)(PPh3)2 (0.200 g; 0.24 mmol) and
phenylacetylene (0.135 g; 1.32 mmol) were heated in
toluene (15 ml) under vacuum in a sealed Schlenk tube
at 55°C for 10 min, resulting in a yellow–orange solu-
tion. The solution was frozen in liquid nitrogen and
PPh3 (0.065 g, 0.24 mmol) added. The Schlenk tube was
then evacuated again and sealed. The solution was
heated at 55°C for a further 0.5 h. The volume of the
solution was reduced in vacuo to a small volume (ca. 3
ml) and then dry hexane added to precipitate (5). This
solid was collected by filtration and washed with several
small portions (ca. 5 ml) of hexane. The solid was then
dissolved in dichloromethane (5 ml) and passed down a
short column (8×4 cm) of silica gel using
dichloromethane as eluent. Addition of ethanol and
reduction of the solvent volume under reduced pressure
yielded (5) as a colourless powder (0.158 g, 60%). m.p.
170–172°C. Anal. Calc. for C63H51OOsP3: C, 68.34; H,
4.64. Found: C, 68.59; H, 5.41. IR (cm−1): 1931s (CO);
2091m (CꢂC); 2078w (OsH). 1H-NMR (CDCl3; l):
8.00–6.48 (m, 50H, PPh3 and C2Ph); −8.49 (d/t, ca.
1
(OsH). H-NMR (CDCl3; l): 7.24–6.97 (m, 45H, PPh3
and SiPh3); −9.01 (broad, ca. 3H, OsH3). 13C-NMR
(CDCl3; l): 187.6 (t, CO, 2JCP=5.1 Hz); 145.8 (s,
SiPh3); 136.7 (t%, PPh3 ipso, 1,3JCP=47.8 Hz); 133.6 (t%,
PPh3 meta, 3,5JCP=11.2 Hz); 129.3 (s, PPh3 para);
127.6 (t%, PPh3 ortho, 2,4JCP=9.4 Hz); 127.1 (s, SiPh3);
126.7 (s, SiPh3). 31P-NMR (CH2Cl2/CDCl3; l): 10.30 (s,
broad). Determination of the T1 values for the hydride
resonances of 3 were carried out by an inversion recov-
ery NMR experiment at 400 MHz. Values for tempera-
ture (°C), chemical shift (ppm), T1 (ms) are: −20,
−9.10, 215; −20, −9.89, 291; −30, −9.12, 228;
−30, −9.91, 315; −40, −9.14, 252; −40, −9.93,
372.
3.5. OsH2[Sn(p−tolyl)3]2(CO)(PPh3)2 (4)
2
2
1H, OsH, JHP(trans)=68.1 Hz, JHP(cis)=25.2 Hz) 13C-
NMR (CDCl3; l): 189.5 (d/t, CO, 2JCP=7.2 Hz,
2JCP%=6.7 Hz); 137.5–123.7 (multiple signals, PPh3 and
OsH3(SiMe3)(CO)(PPh3)2 (0.200 g; 0.24 mmol) and
HSn(p-tolyl)3 (0.200 g; 0.50 mmol) were heated in
toluene (15 ml) at 55°C for 3 h. The volume of the
solution was reduced in vacuo to a small volume (ca. 3
ml) and then dry hexane added to precipitate (4). This
solid was collected by filtration and washed with several
portions (4 ml) of ethanol and then hexane. Recrystal-
lization twice from dichloromethane–hot ethanol gave
(4) as a colourless, micro-crystalline solid (0.119 g,
32%). m.p. 173–174°C. Anal. Calc. for C79H74-
OOsP2Sn2: C, 62.06; H, 4.88. Found: C, 61.49; H, 5.34.
IR (cm−1): 1966s (CO); 1911w, 1901w, (OsH). 1H-
NMR (CDCl3; l): 7.30–6.57 (m, 38H, PPh3 and p-
Ph); the quaternary acetylide carbons were not ob-
2
served. 31P-NMR (CH2Cl2/CDCl3; l): 4.02 (d, JPP
11.5 Hz); −9.90 (t, JPP=11.5 Hz).
=
2
3.7. X-ray crystal structure determination of
OsH3(SiMe3)(CO)(PPh3)2 (1)
A suitable crystal was grown from toluene. Data
were collected on a Siemens SMART diffractometer
with a CCD area detector. Data collection covered a
nominal hemisphere of data by a combination of three
sets of exposures each exposure covering 0.3° in ꢀ.
Lorentz and polarisation corrections were applied and
absorption corrections by the method of Blessing [21]
yielding 22 333 measurements and equivalent reflections
averaged yielding 7944 unique reflections (Rint=
0.0246).
The structure was solved by Patterson and Fourier
techniques using SHELXS-97 [22] and SHELXL-97 [23].
Refinement was by full-matrix least-squares with all
tolyl); 2.27 (s, 6H, C6H4CH3); −7.67 (broad, ca. 2H,
2
OsH2). 13C-NMR (CDCl3; l): 180.9 (d/d, CO, JCP
=
2
75.4 Hz, JCP%=10.8 Hz); 137.5 (s, Sn(C6H4CH3)3 meta,
1
broad); 136.3 (d, PPh3 ipso, JCP=44.9 Hz); 136.2 (s,
1
Sn(C6H4CH3)3 ipso, broad); 135.0 (d, PPh3 ipso, JCP
=
45.4 Hz); 134.4 (d, PPh3 meta, 3JCP=10.4 Hz); 129.9 (s,
PPh3 para); 129.4 (s, PPh3 para); 128.2 (s,
Sn(C6H4CH3)3 para, broad); 128.0 (s, Sn(C6H4CH3)3
ortho); 127.7 (t%, PPh3 ortho, 2,4JCP=19.6 Hz); 127.3 (t%,

464
M. Mo¨hlen et al. / Journal of Organometallic Chemistry 593–594 (2000) 458–464
Chemistry of Organic Silicon Compounds Part II, Wiley, New
York, 1989, pp. 1415–1477.
[2] B.J. Aylett, Adv. Inorg. Chem. Radiochem. 25 (1982) 1.
[3] For a review see: I. Ojima, in: S. Patai, Z. Rappoport (Eds.),
The Chemistry of Organic Silicon Compounds Part II, Wiley,
New York, 1989, pp. 1479–1526.
[4] M.L. Buil, P. Espinet, M.A. Esteruelas, F.J. Lahoz, A. Lledo´s,
J.M. Mart´ınez-Ilarduya, F. Maseras, J. Modrego, E. On˜ate,
L.A. Oro, E. Sola, C. Valero, Inorg. Chem. 35 (1996) 1250.
[5] K. Hu¨bler, U. Hu¨bler, W.R. Roper, P. Schwerdtfeger, L.J.
Wright, Chem. Eur. J. 3 (1997) 1608.
[6] L.J. Procopio, D.H. Berry, J. Am. Chem. Soc. 113 (1991)
4039.
[7] H. Kono, N. Wakao, K. Ito, Y. Nagai, J. Organomet. Chem.
132 (1977) 53.
[8] R.N. Haszeldine, L.S. Malkin, R.V. Parish, J. Organomet.
Chem. 182 (1979) 323.
non-hydrogen atoms being allowed to assume anisotropic
thermal motion. Hydrogen atoms, other than those
bonded to osmium, were placed geometrically and refined
with a riding model with Uiso 20% greater than the carrier
atom. The hydrogen atoms bonded to osmium were
located from a difference map, that trans to the carbonyl
group being clearly resolved and the remaining two less
so. The coordinates of these hydrides were allowed to
refine with thermal parameter fixed at 20% greater than
that of osmium. Refinement converged to conventional
R=0.0223 for the 6885 data with [I\2|(I)]. Crystal data
and refinement parameters are given in Table 1 and
selected bond lengths and angles in Table 2.
[9] M. Knorr, S. Gilbert, U. Schubert, J. Organomet. Chem. 347
(1988) C17.
4. Supplementary material
[10] U. Schubert, S. Gilbert, S. Mock, Chem. Ber. 125 (1992) 835.
[11] (a) K. Hu¨bler, P.A. Hunt, S.M. Maddock, C.E.F. Rickard,
W.R. Roper, D.M. Salter, P. Schwerdtfeger, L.J. Wright,
Organometallics 16 (1997) 5076. (b) D.M. Salter, PhD. Thesis,
University of Auckland, New Zealand, 1993.
[12] G.R. Clark, C.E.F. Rickard, W.R. Roper, D.M. Salter, L.J.
Wright, Pure Appl. Chem. 62 (1990) 1039.
[13] S.M. Maddock, C.E.F. Rickard, W.R. Roper, L.J. Wright,
Organometallics 15 (1996) 1793.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 127541. Copies of this informa-
tion can be obtained free of charge from the Director,
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (Fax:
+44-1223-336033; e-mail: deposit@ccdc.cam.ac.uk or
www: http://www.ccdc.cam.ac.uk).
[14] D.G. Gusev, T.T. Nadasdi, K.G. Caulton, Inorg. Chem. 35
(1996) 6772.
[15] G.R. Clark, K.R. Flower, C.E.F. Rickard, W.R. Roper, D.M.
Salter, L.J. Wright, J. Organomet. Chem. 462 (1993) 331.
[16] U. Schubert, K. Bahr, J. Mu¨ller, J. Organomet. Chem. 327
(1987) 357.
[17] D.G. Hamilton, R.H. Crabtree, J. Am. Chem. Soc. 110 (1988)
4126.
[18] D.D. Perrin, W.L.F. Armarego, Purification of Laboratory
Chemicals, third ed., Pergamon, New York, 1988.
[19] C.E.F. Rickard, W.R. Roper, G.E. Taylor, J.M. Waters, L.J.
Wright, J. Organomet. Chem. 389 (1990) 375.
Acknowledgements
We thank the University of Auckland Research Com-
mittee for partial support of this work through grants-in-
aid. M. Mo¨hlen gratefully acknowledges the award of a
Feodor-Lynen-Forschungsstipendium from the Alexan-
der von Humboldt Foundation.
[20] S. Tannenbaum, S. Kaye, G.F. Lewenz, J. Am. Chem. Soc. 75
(1953) 3753.
[21] R.H. Blessing, Acta Crystallogr. A 51 (1995) 33.
[22] G.M. Sheldrick, Acta Crystallogr. A 46 (1990) 467.
[23] G.M. Sheldrick, SHELXL-97. Program for the Refinement of
Crystal Structures, University of Go¨ttingen, Germany, 1997.
References
[1] (a) J.Y. Corey, J. Braddock-Wilking, Chem. Rev. 99 (1999)
175. (b) T.D. Tilley, in: S. Patai, Z. Rappoport (Eds.), The
.