6016 Organometallics, Vol. 16, No. 26, 1997
Notes
Hz, cis to Si), 21.8 (J (PP) ) 16 Hz, J (PtP) ) 1635 Hz, trans to
Si). Anal. Calcd for C30H43F3P2PtSi: C, 48.31; H, 5.81; F, 7.64.
Found: C, 48.31; H, 5.79; F, 7.64.
splitting due to Rh-H and Rh-P coupling, the equilib-
rium of the first step in Scheme 3 is favored to the left.
All these observations suggest that reaction 1 involves
reductive elimination of HSiAr3 from the Rh(III) com-
plex as the rate-determining step and is motivated by
the thermodynamic stability of the H-Pt-Si bond being
greater than that of the corresponding coordination
bonds in the Rh(III) complexes.
The ligand transfer shown in the present paper
suggests the potential utility of the hydridosilylmetal
complexes in the synthesis of transition-metal silyl
complexes and will provide a useful tool to compare the
relative stabilities of H-M-Si coordination among
different transition metals.
The reaction of 1c with Pt(PEt3)4 was carried out analo-
gously to give 2c (60%). 1H NMR: δ -2.88 (dd, 1H, J (PtransH)
) 150 Hz, J (PcisH) ) 19 Hz, J (PtH) ) 858 Hz, Pt-H), 0.67
(td, 9H, J (PH) ) 16 Hz, J (HH) ) 7 Hz, PCH2CH3), 0.83 (td,
9H, J (PH) ) 16 Hz, J (HH) ) 7 Hz, PCH2CH3), 1.11 (m, 6H,
PCH2CH3), 1.49 (m, 6H, PCH2CH3), 7.27 (d, 6H, J (HH) ) 7
Hz, Si-C6H4-m), 7.70 (d, 6H, J (HH) ) 9 Hz, Si-C6H4-o). 31P-
{1H} NMR: δ 17.0 (J (PP) ) 16 Hz, J (PtP) ) 2398 Hz, cis to
Si), 21.9 (J (PP) ) 16 Hz, J (PtP) ) 1663 Hz, trans to Si). Anal.
Calcd for
C30H43Cl3P2PtSi: C, 45.31; H, 5.45; Cl, 13.37.
Found: C, 45.54; H, 5.49; Cl, 13.93.
P r ep a r a tion of cis-P tH(SiP h 3)(P Et3)2 (2a ). To a pentane
(5 mL) solution of Pt(PEt3)4 (419 mg, 0.63 mmol) was added
HSiPh3 (196 mg, 0.75 mmol) at room temperature. The yellow
solution soon changed to colorless, and white solid was
generated after 1 min on stirring. After 1 h the resulting solid
product was collected by filtration, washed with pentane, and
dried in vacuo (284 mg, 65%).
Rea ction of Rh Cl(P Et3)3 w ith 2a . RhCl(PEt3)3 and 2a
were dissolved in THF (5 mL), and the resulting solution was
stirred at room temperature for 8 h. The solvent was removed
in vacuo, and NMR spectra of the resulting orange viscous
product were measured. The 1H and 31P{1H} NMR spectra
showed peaks for 2a and RhCl(PEt3)3 only.
Exp er im en ta l Section
Gen er a l Meth od s. All manipulations of the complexes
were carried out using standard Schlenk techniques under an
argon or nitrogen atmosphere. RhCl(H)(SiAr3)[P(i-Pr)3]2,14
RhCl(PEt3)3,15 and Pt(PEt3)416 were prepared according to the
literature method. All the solvents were distilled from drying
reagents and stored under nitrogen. NMR spectra (1H, 400
MHz; 31P, 160 MHz) were recorded in benzene-d6 on a J EOL
EX-400 spectrometer. Peak positions of the 31P NMR were
referenced to external 85% H3PO4. Elemental analyses were
carried out with a Yanaco MT-5 CHN autocorder and with a
Yanaco YS-10 autocorder.
Rea ction s of 1a -c w ith P t(P Et3)4. Complex 1a (151 mg,
0.21 mmol) dispersed in pentane (5 mL) was mixed with Pt-
(PEt3)4 (141 mg, 0.21 mmol) at room temperature. Stirring
the reaction mixture turned the solid remaining undissolved
from yellow to pale yellow and the solution from colorless to
yellow-orange. After 12 h, the resulting solid was collected
by filtration and dried in vacuo to give 2a as a white solid (87
mg, 60%). Recrystallization from a toluene-pentane mixture
afforded colorless crystals. 1H NMR: δ -2.43 (dd, 1H,
J (PtransH) ) 151 Hz, J (PcisH) ) 21 Hz, J (PtH) ) 873 Hz, Pt-
H), 0.77 (td, 9H, J (PH) ) 16 Hz, J (HH) ) 7 Hz, PCH2CH3),
0.92 (td, 9H, J (PH) ) 16 Hz, J (HH) ) 7 Hz, PCH2CH3), 1.24
(m, 6H, PCH2CH3), 1.54 (m, 6H, PCH2CH3), 7.20 (t, 3H, J (HH)
) 7 Hz, Si-C6H5-p) 7.29 (t, 6H, J (HH) ) 7 Hz, Si-C6H5-m), 8.07
(d, 6H, J (HH) ) 7 Hz, Si-C6H5-o). 31P{1H} NMR: δ 17.8 (J (PP)
) 16 Hz, J (PtP) ) 2414 Hz, cis to Si), 22.0 (J (PP) ) 16 Hz,
J (PtP) ) 1616 Hz, trans to Si). Anal. Calcd for C30H46P2PtSi:
C, 52.08; H, 6.70. Found: C, 51.94; H, 6.64.
The filtrate after separation of 2a from the reaction mixture
was reduced to ca. 1 mL by evaporation of the solvent. The
31P{1H} NMR spectrum of the mixture showed peaks due to
2a and RhCl(PEt3)3 (δ 19.3 (dd) and 36.4 (dt)) in addition to
several uncharacterized Rh-containing products. Leaving the
mixture at 25 °C caused separation of RhCl(PEt3)3 as orange
crystals.
The reaction of 1b with Pt(PEt3)4 was carried out analo-
gously to give 2b (56%). 1H NMR: δ -2.71 (dd, 1H, J (PtransH)
) 151 Hz, J (PcisH) ) 21 Hz, J (PtH) ) 867 Hz, Pt-H), 0.70
(td, 9H, J (PH) ) 16 Hz, J (HH) ) 7 Hz, PCH2CH3), 0.87 (td,
9H, J (PH) ) 16 Hz, J (HH) ) 7 Hz, PCH2CH3), 1.15 (m, 6H,
PCH2CH3), 1.50 (m, 6H, PCH2CH3), 6.99 (dd, 6H, J (FH) ) 9
Hz, J (HH) ) 9 Hz, Si-C6H4-o), 7.80 (d, 6H, J (HH) ) 6 Hz, Si-
C6H4-m). 31P{1H} NMR: δ 17.4 (J (PP) ) 16 Hz, J (PtP) ) 2410
Cr ysta l Str u ctu r e Deter m in a tion . Crystals of 2a suit-
able for crystallography were obtained by recrystallization
from toluene-pentane and mounted in glass capillary tubes
under argon. The unit cell parameters were obtained by least-
squares refinement of 2θ values of 20 reflections with 20° e
2θ < 30°. Intensities were collected for Lorentz and polariza-
tion effects on a Rigaku AFC-5R automated four-cycle diffrac-
tometer by using Mo KR radiation (λ ) 0.710 69 Å) and the
ω-2θ scan method, and an empirical absorption correction (ψ
scan) was applied. Crystal data for 2a : C30H46P2PtSi; Mr,
691.82; monoclinic; space group, P21 (No. 4); a, 9.833(4) Å; b,
19.065(6) Å; c, 10.415(4) Å; â, 95.29(3)°; V, 1536(1) Å3; Z, 2;
µ(Mo KR), 47.05 cm-1; F(000), 696.00; Dcalcd, 1.495 g cm-3
;
crystal size, 0.5 × 0.7 × 0.9 mm; number of unique reflections,
3672; number of reflections used (I g 3σ(I)), 2624; number of
variables, 306; R(Fo), 0.037; Rw(Fo), 0.028; GOF, 1.33.
Calculations were carried out by using the program package
TEXSAN on a DEC Micro VAX-II computer. Atomic scattering
factors were obtained from the literature.17 A full-matrix least-
squares refinement was used for non-hydrogen atoms with
anisotropic thermal parameters. The position of the hydride
ligand was determined by the difference Fourier technique,
while the other hydrogens were located by assuming ideal posi-
tions (d(C-H) ) 0.95 Å) and included in the structure calcu-
lation without further refinement of the parameters. Param-
eters of the hydride were fixed in the structural calculations.
Crystallographic results for 2c are included in the Support-
ing Information.
Ack n ow led gm en t. This work was financially sup-
ported by a Grant-in-Aid for Scientific Research from
the Ministry of Education, Science, Culture, and Sports
of J apan. T.K. is grateful to the J apan Society for
Promotion of Science (J SPS) for a Grant-for-Aid for
J SPS Fellows.
Su p p or tin g In for m a tion Ava ila ble: Tables of positional
parameters, thermal parameters, bond distances and angles,
and crystallographic data and details of refinement of 2a and
2c and a figure giving the structure of 2c (13 pages). Ordering
information is given on any current masthead page.
(13) Substitution of the P(i-Pr)3 ligand bonded to 1 by PEt3 liberated
from Pt(PEt3)4 might occur prior to the ligand transfer. The resulting
RhCl(H)(SiAr3)(PEt3)2 or RhCl(H)(SiAr3)(PEt3)[P(i-Pr)3] would undergo
reductive elimination of HSiAr3 initiated by further PEt3 ligation (A
mechanism) in addition to the direct reductive elimination from the
pentacoordinated Rh complexes.
(14) Osakada, K.; Koizumi, T.; Yamamoto, T. Organometallics 1997,
16, 2063.
OM9706976
(15) Haines, L. M. Inorg. Chem. 1970, 9, 1517.
(16) Pearson, R. G.; Louw, W.; Rajaram, J . Inorg. Chim. Acta 1974,
9, 251.
(17) International Tables for X-ray Crystallography; Kynoch: Bir-
mingham, England, 1974; Vol. IV.