Ruthenium (η2-Silane) Linkages
Organometallics, Vol. 21, No. 24, 2002 5357
for a given hydride location and the cross-peak areas arising
from exchange were normalized to 100%. For processes such
as this, involving the exchange of nuclei between two sites,
exact rate constants can then be determined via analysis of
the intensity versus mixing time profile or via the more
comprehensive matrix method.14 The experiment was repeated
over a range of temperatures, and the activation parameters
∆Hq and ∆Sq were determined by nonlinear regression using
SPSS for Windows version 9.0.
Syn th esis an d Ch ar acter ization of Ru H2{(η2-H-SiP h 2)O-
(SiHP h 2)}(P P h 3)3 (5). A solution of triphenylphosphine (313
mg, 1.20 mmol) and RuH2[(η2-HSiPh2)2O](PCy3)2 (4) (250 mg,
0.24 mmol) in pentane (15 mL) was stirred overnight at room
temperature. The resulting white powder was filtered off and
washed with small amounts of pentane before being dried
under argon and finally under vacuum (yield 85%). Anal. Calcd
for C78H68OSi2P3Ru: C, 73.71; H, 5.35. Found: C, 74.13; H,
5.71. 1H NMR (toluene-d8, 400.13 MHz) 293 K: δ 9.12 (m, 3H,
RuH3), 5.31 (s, 1H, Si-H), 6.9-7.9 (m, 45H, PPh3); 213 K:
-8.75 (brt, 2H, RuH3), -9.15 (dt, 1H, RuH3), 5.26 (s, 1H, Si-
H). 31P{1H} NMR (toluene-d8, 161.97 MHz) 293 K: 40.14 (s);
213 K: 42.62 (t, J P-P ) 23 Hz), 38.49 (d, J P-P ) 23 Hz). 1H
NMR (thf-d8, 500.13 MHz) 300 K: -9.65 (m, 3H, RuH3), 4.61
(s, 1H, Si-H), 6.8-7.4 (m, 45H, PPh3); 203 K: -9.73 (t, 1H,
RuH3), -9.43 (dt, 2H, RuH3), 4.23 (s, 1H, Si-H). 31P{1H} NMR
(thf-d8, 202.46 MHz, 300 K): 39.62 (s). 1H-29Si{1H} INEPT
following formula: w ) 1/[σ2(Fo2) + (aP)2 + bP] where P )
2
(Fo2 + 2Fc )/3. Statistical disorder was observed on some phenyl
rings. A model was found in each case and refined by using
some restraints on interatomic lengths and angles and on some
anisotropic displacement parameters in order to lead to
reasonable chemical models. Two distinct solvent molecules
were also located: tetrahydrofuran and ethanol. The best
convergence was obtained with occupancy values equal to 0.25.
Some restraints on interatomic distances, angles, and aniso-
tropic displacement parameters were necessary to improve the
models. The molecule was drawn with the program CAM-
ERON with 40% probability displacement ellipsoids for non-
hydrogen atoms.32
Th eor etica l Meth od s
DFT calculations were performed with the Gaussian 98
series of programs33 using the nonlocal hybrid functional
denoted as B3LYP.34 For ruthenium, the core electrons were
represented by a relativistic small-core pseudopotential using
the Durand-Barthelat method.35 The 16 electrons correspond-
ing to the 4s, 4p, 4d, and 5s atomic orbitals were described by
a (7s, 6p, 6d) primitive set of Gaussian functions contracted
to [5s, 5p, 3d]. Standard pseudopotentials developed in Tou-
louse were used to describe the atomic cores of all other non-
hydrogen atoms (C, O, Si, and P).36 A double plus polarization
valence basis set was employed for each atom (d-type function
exponents were 0.80 and 0.85, 0.45 and 0.45, respectively). For
hydrogen, a standard primitive (4s) basis contracted to [2s]
was used. A p-type polarization function was added for the
hydrogen atoms directly bound to ruthenium. The geometry
of the various critical points on the potential energy surface
was fully optimized with the gradient method available in
Gaussian 98. Calculations of harmonic vibrational frequencies
were performed to determine the nature of each critical point.
(C6D6, 293 K, 79.5 MHz): -21.4 (s, Si-H), 11.69 (d, J Si-P
9.4 Hz, Ru-H-Si).
)
Syn th esis an d Ch ar acter ization of Ru H2{(η2-H-SiP h 2)O-
[Si(OH)P h 2]}(P P h 3)3 (6). Several attempts were made to
obtain crystals of 5 suitable for an X-ray determination. They
were all unsuccessful. However, slow diffusion of pentane into
a THF solution of 5 resulted, after several days, in a few yellow
crystals characterized by NMR and X-ray structure as RuH2-
{(η2-H-SiPh2)O[Si(OH)Ph2]}(PPh3)3 (6). 6 derives from 5 prob-
ably as a result of partial hydrolysis due to water contamina-
Ack n ow led gm en t. We are grateful for support from
the CNRS and The British Council/Alliance program.
We thank the Centre Informatique National de l’En-
seignement Superieur (CINES, Montpellier, France) for
a generous allocation of computer time.
1
tion. H NMR (toluene-d8, 400.13 MHz, 293 K): δ -9.15 (m,
3H, RuH3), 6.9-7.9 (m, 45H, PPh3).
Cr ysta l Da ta for 6. Data were collected at low temperature
(Table 5) on a Stoe imaging plate diffraction system (IPDS),
equipped with an Oxford Cryosystems cryostream cooler device
and using graphite-monochromated Mo KR radiation (λ )
0.71073 Å). A half-sphere of data was collected by æ axis
rotation with an increment of 1.5° over 200° and 133 expo-
sures. The final unit cell parameters were obtained by least-
squares refinement of a set of 5000 well-measured reflections,
and crystal decay was monitored by measuring 200 reflections
by image. No significant fluctuation of the intensities was
observed. The structure was solved by direct methods using
the program SIR9229 and refined by least-squares procedures
on F2 with SHELXL-93.30 The atomic scattering factors were
taken from International Tables for X-Ray Crystallography.31
All hydrogen atoms were located on a difference Fourier map,
but introduced and refined with a riding model. Hydride atoms
labeled H, H′, and H′′ were isotropically refined by using a
free variable for the U[iso]. All non-hydrogen atoms were
anisotropically refined, and a weighting scheme was used in
the last cycles of refinement. Weights are calculated from the
Su p p or tin g In for m a tion Ava ila ble: Tables and figures
of more extensive computational results. X-ray crystallographic
files (CIF). This material is available free of charge via the
Internet at http://pubs.acs.org.
OM0206148
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