Palladium-platinum heterobimetallic complexes with bridging silicon ligands. Structure and reaction with isonitrile to afford a platinacyclopentane containing Si, N, and C atoms

Article abstract of DOI:10.1021/om049858d

The reaction of Pt(SiHPh₂)₂(PEt₃) ₂ with Pd(PEt₃)₃ produced heterodinuclear complexes with bridging diphenylsilyl ligands (Et₃P)Pt(μ- η²-SiHPh₂)₂Pd(PEt₃) (1) and (Et₃P)₂Pt(μ-η²-SiHPh₂) ₂Pd(PEt₃) (2). Each product was isolated and fully characterized. X-ray crystallography of 2 and NMR spectra of 2 and 2-d ₂ at 25 °C indicated the presence of two bridging SiHPh ₂ (or SiDPh₂) ligands, which were bonded to one metal center via a M-Si single bond and to the other via a Si-H-M three-center, two-electron bond. The ¹H NMR spectrum of 2 at -90 °C exhibited a peak atδ -8.61 due to a hydrido ligand bonded to the Pt center, indicating the structure (Et₃P)₂PtH(μ-SiPh ₂)(μ-η²-SiHPh₂)Pd(PEt₃) in the solution at low temperature. Complex 2 reacted with CN-t-Bu to form a mixture of (Et₃P)(t-BuNC)-Pt(SiPh₂-CH₂-N(t-Bu)- SiPh₂) (3) and [(Et₃P)(t-BuNC)Pt(μ-SiPh ₂)]₂ (4). Complex 3 contained the platinacyclopentane group, whose five-membered ring was composed of Pt, Si, N, and C atoms.

Full text of DOI:10.1021/om049858d

Organometallics 2004, 23, 4771-4777
4771
P a lla d iu m -P la tin u m Heter obim eta llic Com p lexes w ith
Br id gin g Silicon Liga n d s. Str u ctu r e a n d Rea ction w ith
Ison itr ile to Affor d a P la tin a cyclop en ta n e Con ta in in g Si,
N, a n d C Atom s
Tetsuyuki Yamada,† Makoto Tanabe,† Kohtaro Osakada,*,† and Yong-J oo Kim‡
Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku,
Yokohama 226-8503, J apan, and Department of Chemistry, Kangnung National University,
Kangnung 210-702, Korea
Received February 26, 2004
The reaction of Pt(SiHPh2)2(PEt3)2 with Pd(PEt3)3 produced heterodinuclear complexes
with bridging diphenylsilyl ligands (Et3P)Pt(µ-η2-SiHPh2)2Pd(PEt3) (1) and (Et3P)2Pt-
(µ-η2-SiHPh2)2Pd(PEt3) (2). Each product was isolated and fully characterized. X-ray
crystallography of 2 and NMR spectra of 2 and 2-d2 at 25 °C indicated the presence of two
bridging SiHPh2 (or SiDPh2) ligands, which were bonded to one metal center via a M-Si
1
single bond and to the other via a Si-H-M three-center, two-electron bond. The H NMR
spectrum of 2 at -90 °C exhibited a peak at δ -8.61 due to a hydrido ligand bonded to the
Pt center, indicating the structure (Et3P)2PtH(µ-SiPh2)(µ-η2-SiHPh2)Pd(PEt3) in the solution
at low temperature. Complex 2 reacted with CN-t-Bu to form a mixture of (Et3P)(t-BuNC)-
Pt(SiPh2-CH2-N(t-Bu)-SiPh2) (3) and [(Et3P)(t-BuNC)Pt(µ-SiPh2)]2 (4). Complex 3 contained
the platinacyclopentane group, whose five-membered ring was composed of Pt, Si, N, and C
atoms.
In tr od u ction
(SiHPh2)2(PMe3)2 was reported to cause ligand substitu-
tion, giving Pt(SiHPh2)2(PMe3)(CNR), rather than in-
sertion of the isonitrile into the Pt-Si bond.5 These
results suggest that 1,1-insertion of isonitrile into Pd-
Si bonds takes place more easily than that into Pt-Si
bonds.
Isonitrile (R-NtC) plays an important role in orga-
nometallic chemistry not only as a ligand for transition
metal complexes but also as a substrate for reactions
that involve single or multiple 1,1-insertion of isonitrile
into the metal-carbon bond to give the complexes with
a M-C(dNR)-C group.1 Many silyl complexes of tran-
sition metals undergo facile 1,2-insertion of CdC and
CtC bonds into the M-Si bond to form new M-C and
C-Si bonds.2 The number of papers on the insertion
reactions of isonitriles with transition metal silyl com-
plexes, however, is much smaller than those of the
reactions of isonitriles with alkyl transition metal
complexes. Silyl complexes of Sc and Zr undergo inser-
tion of isonitrile into a M-Si bond and form complexes
with η2-coodinated iminoacyl ligands.3 Pd(OAc)2 cata-
lyzes bissilylation of aryl isonitrile with disilanes, which
involves insertion of the isonitrile into the Pd-Si bonds
as a crucial step.4 The reaction of isonitriles with Pt-
Recently we prepared a Pd-Pt hetereobimetalic
complex whose metal centers were bridged by two
-SiHPh2 ligands.6,7 Reaction of isonitriles with these
heterobimetallic complexes would be of significant
interest because the Pd-Si and Pt-Si bonds in the
same molecule have different reactivity toward iso-
nitrile. In this paper, we report the preparation and
structures of Pd-Pt heterobimetallic complexes with
PEt3 and bridging diphenylsilyl ligands as well as the
reaction of a Pd-Pt complex with an isonitrile to form
a new platinacyclopentane containing Si, Pt, C, and N
atoms in the five-membered ring.
(4) Ito, Y.; Suginome, M.; Matsuura, T.; Murakami, M. J . Am. Chem.
Soc. 1991, 113, 8899.
(5) Kim, Y.-J .; Choi, E.-H.; Lee, S. W. Organometallics 2003, 22,
3316.
† Tokyo Institute of Technology.
‡ Kangnung National University.
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F.; Yanai, K.; Onitsuka, K.; Takahashi, S. Angew. Chem., Int. Ed. Engl.
1996, 35, 1554.
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Rapporport, Z., Eds.; J ohn Wiley & Sons: New York, 1998; Vol. 2, Part
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F. Organometallics 1995, 14, 4910. (e) Braunstein, P.; Morise, X.
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M. Organometallics 1999, 18, 1791. (g) Sakaba, H.; Ishida, K.; Horino,
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10.1021/om049858d CCC: $27.50 © 2004 American Chemical Society
Publication on Web 08/25/2004

4772 Organometallics, Vol. 23, No. 20, 2004
Yamada et al.
Resu lts a n d Discu ssion
The reaction of Pt(SiHPh2)2(PEt3)2 with Pd(PEt3)3
produces a mixture of Pd-Pt bimetallic complexes
(Et3P)Pt(µ-η2-SiHPh2)2Pd(PEt3) (1) and (Et3P)2Pt(µ-η2-
SiHPh2)2Pd(PEt3) (2) with two bridging Si-containing
ligands (eq 1). Complexes 1 and 2 are isolated from the
F igu r e 1. ORTEP drawing of 1 at the 50% ellipsoidal
level. The molecule has a point of C2 crystallographic
symmetry at the midpoint of the Pd and Pt atoms. The
atoms with asterisks are crystallographically equivalent
to those with the same number without asterisk. Selected
bond distances (Å) and angles (deg): Pd1/Pt1-Pd1*/Pt1*
2.6697(8), Pd1/Pt1-Si1 2.316(1), Pd1/Pt1-Si1* 2.388(1),
Pd1/Pt1-P1 2.2889(11), P1-Pd1/Pt1-Si1 102.16(4).
mixture in 34% and 25% yields, respectively. There have
been a number of Pt-Pt and Pd-Pd dinuclear com-
plexes with bridging Si ligands reported so far.8-15 They
are complexes with structures similar to 1, [(R3P)Pt(µ-
η2-SiHR′2)]2,8,9d [(R3P)Pt(µ-η2-SiH2R′)]2,13a,b,d and [(R3P)-
Pd(µ-η2-SiHR′2)]2.15 The Pd complex with one phosphine
ligand at one metal center and two phosphine ligands
at the other, (Me3P)2Pd(µ-η2-SiHPh2)2Pd(PMe3), was
also prepared and characterized.15
Complex 1 was characterized by X-ray crystallogra-
phy and NMR spectroscopy. Figure 1 shows the molec-
ular structure containing a planar PdPtSi2 four-mem-
bered ring. A crystallographic C2 symmetry center at
the midpoint of the ring imposes disorder of the posi-
tions of Pd and Pt, similarly to (Cy3P)Pt(µ-η2-SiHPh2)2-
Pd(PCy3).6 Thus, the molecular structure is expressed
as an average of the molecules with different orientation
in the crystal lattice. The distances of the two crystal-
lographically independent metal-Si bonds differ sig-
nificantly from each other (2.316(1) and 2.388(1) Å).
These bonds are assigned to metal-Si single bonds and
the bond in the M-H-Si group with a three-center, two-
electron bond, respectively, although the hydrogen
atoms were not found in the final D-map.
The NMR data of 1 at room temperature indicate the
heterodinuclear structure with M-H-Si three-center,
1
two-electron bonds. The H NMR signals for the PCH2
hydrogens are observed as two apparent quintets due
to virtual coupling at δ 1.49 and 1.27 in equal intensity.
The 1H NMR spectrum (25 °C, C6D6) shows doublet
signals at δ 2.71 and 2.06. The 1H-195Pt coupling
constants obtained from these signals (96 and 650 Hz)
indicate that the signals are attributed to Pd-H-Si and
2
Pt-H-Si, respectively. The H NMR spectrum of the
complex (Et3P)Pt(µ-η2-SiDPh2)2Pd(PEt3) (1-d2), obtained
from the reaction of D2SiPh2, contains signals at δ 2.74
and 2.07 with reasonable coupling constants (2J (PtD)
) 15 Hz, 1J (PtD) ) 90 Hz). The 31P{1H} NMR spectrum
exhibits two doublets at δ 28.3 and 15.8 (3J (PP) ) 55
Hz). The former signal, showing a much larger Pt-P
coupling constant (3556 Hz) than the latter (258 Hz),
1
is assigned to PEt3 bonded to Pt. The H and 31P{1H}
NMR spectra do not change in the temperature range
from -90 to 25 °C. The virtual coupling observed in the
PCH2 signals in the 1H NMR spectrum, a large P-P
coupling constant, and crystallographic results showing
the metal-metal distance of 2.6697(8) Å indicate the
presence of a Pd-Pt bond in the molecule.
(8) Auburn, M.; Ciriano, M.; Howard, J . A. K.; Murray, M.; Pugh,
N. J .; Spencer, J . L.; Stone, F. G. A.; Woodward, P. J . Chem. Soc.,
Dalton Trans. 1980, 659.
Figure 2 shows crystallographic results of complex 2.
The Pd, Pt, and two Si atoms form a planar four-
membered ring similar to 1 and other diplatinum and
dipalladium complexes with two bridging silyl ligands.
The phosphorus atoms of two PEt3 ligands bonded to
the Pt center are out of the plane formed by the metals
and Si atoms (Figure 2b). The Pd-Pt distance (2.757(1)
Å) is longer than that of 1 and is within the range of
normal metal-metal bonding.16 One of the two Pd-Si
bonds (2.388(3) Å) is longer than the other (2.300(3) Å),
while the Pt-Si bond lengths differ by 0.06 Å (Pt-Si )
2.415(3) and 2.361(3) Å). The bond parameters suggest
a structure containing Si-H-Pd and Si-H-Pt three-
center, two-electron bonds (Chart 1 A), similar to
[(Cy3P)Pd(µ-η2-SiHPh2)]2 (Pd-Si ) 2.326(2) and 2.384(2)
Å).6 The hydrogen positions of 2 were not found by
crystallography. Braddock-Wilking obtained a dinuclear
(9) (a) Zarate, E. A.; Tessier-Youngs, C. A.; Youngs, W. J . J . Am.
Chem. Soc. 1988, 110, 4068. (b) Zarate, E. A.; Tessier-Youngs, C. A.;
Youngs, W. J . J . Chem. Soc., Chem. Commun. 1989, 577. (c) Anderson,
A. B.; Shiller, P.; Zarate, E. A.; Tessier-Youngs, C. A.; Youngs,
W. J . Organometallics 1989, 8, 2320. (d) Sanow, L. M.; Chai, M.;
McConnville, D. B.; Galat, K. J .; Simons, R. S.; Rinaldi, P. L.; Youngs,
W. J .; Tessier, C. A. Organometallics 2000, 19, 192.
(10) Michalczyk, M. J .; Recatto, C. A.; Calabrese, J . C.; Fink, M. J .
J . Am. Chem. Soc. 1992, 114, 7955.
(11) Heyn, R. H.; Tilley, T. D. J . Am. Chem. Soc. 1992, 114, 1917.
(12) Shimada, S.; Tanaka, M.; Honda, K. J . Am. Chem. Soc. 1995,
117, 8289.
(13) (a) Levchinsky, Y.; Rath, N. P.; Braddock-Wilking, J . Organo-
metallics 1999, 18, 2583. (b) Braddock-Wilking, J .; Levchinsky, Y.;
Rath, N. P. Organometallics 2000, 19, 5500. (c) Braddock-Wilking, J .;
Levchinsky, Y.; Rath, N. P. Organometallics 2001, 20, 474. (d)
Braddock-Wilking, J .; Levchinsky, Y.; Rath, N. P. Inorg. Chim. Acta
2002, 330, 82.
(14) Fu¨rstner, A.; Krause, H.; Lehmann, C. W. Chem. Commun.
2001, 2372.
(15) (a) Kim, Y.-J .; Lee, S.-C.; Park, J .-I.; Osakada, K.; Choi, J .-C.;
Yamamoto, T. Organometallics 1998, 17, 4929. (b) Kim, Y.-J .; Lee, S.-
C.; Park, J .-I.; Osakada, K.; Choi, J .-C.; Yamamoto, T. J . Chem. Soc.,
Dalton Trans. 2000, 417.
(16) Cotton, F. A.; Walton, R. A. Multiple Bonds between Metal
Atoms; Wiley: New York, 1982.

Pd-Pt Heterobimetallic Complexes
Organometallics, Vol. 23, No. 20, 2004 4773
F igu r e 3. NMR spectra of 2 and 2-d2. (a) 1H NMR of 2 at
25 °C (400 MHz in CD2Cl2). The peaks with asterisks are
attributed to contamination from the phosphine ligands in
F igu r e 2. ORTEP drawing of 2 at the 50% ellipsoidal
level. One of the two crystallographically independent
molecules is shown. Selected bond distances (Å) and angles
(deg): Pd1-Pt1 2.757(1), Pd1-Si1 2.300(3), Pd1-Si2
2.388 (3), Pt1-Si1 2.415(3), Pt1-Si2 2.361(3), Pd1-P1
2.281 (3), Pt1-P2 2.383(3), Pt1-P3 2.325(3), Pd1-Pt1-
Si1 52.30(8), Pd1-Pt1-Si2 54.97(8), Pt1-Pd1-Si1 56.19(8),
Pt1-Pd1-Si2 54.06(8), Si1-Pt1-Si2 106.94(12), Si1-
Pd1-Si2 109.91(12), Pt1-Pd1-P1 155.20 (9), Pd1-Pt1-
P2 110.46(8), Pd1-Pt1-P3 133.07(9).
2
1. (b) H NMR of 2-d2 at 25 °C (77 MHz in CH2Cl2).
ous evidence for the bonding mode of the hydrides and
metals. The 2H NMR spectrum of (Et3P)2Pt(µ-η2-SiDPh2)2-
Pd(PEt3) (2-d2) (25 °C) contains signals at δ 2.15
(2J (PtD) ) 10 Hz) and 0.41 (1J (PtD) ) 106 Hz)18 (Figure
3b). The chemical shift and coupling constant for the
latter signal support the assignment for the resonance
to the deuterium in a Pt-D-Si three-center, two-
electron bond. The 1J (PtH) value for the hydrogen
bonded to Pt of 2 can be calculated to be 690 Hz by
Ch a r t 1
1
2
comparison of the gyromagnetic ratios of H and H.19
The 31P{1H} NMR spectrum at 25 °C contains a single
broad peak at δ 5.2, suggesting fluxional behavior of the
molecule on the NMR time scale. Since the hydrides
were not located in the solid state X-ray crystal struc-
ture, the exact nature of the bonding interaction is not
known in the solid. The NMR data at room temperature,
however, do support a M-H-Si interaction (M ) Pd,
Pt). Thus, complex 2 has a four-membered core com-
posed of Pd, Pt, and two Si atoms and Pd-H-Si and
Pt-H-Si bonds at room temperature in solution. Par-
tial dissociation or intramolecular exchange of PEt3
ligands in solution is suggested by broadening of the
room-temperature 31P{1H} NMR signal.15
platinum complex from the reaction of silafluorene with
Pt(η2-C2H4)(PPh3)2 and assigned the structure (Ph3P)2-
Pt(H){µ-Si(C12H8)}{µ-η2-SiH(C12H8)}Pt(PPh3) (Chart 1,
B) on the basis of the NMR (1H, 31P, and 29Si) spectra
at -50 °C.17
1
The H NMR spectrum of 2 (25 °C, 400 MHz in CD2-
Cl2) exhibits the signal for the Si-H-Pd hydrogen at δ
The 31P{1H} NMR spectrum of 2 at -90 °C shows a
triplet and doublet (3J (PP) ) 27 Hz) at δ 7.2 and -0.96.
The latter signal with a large 1J (PtP) coupling (3223
Hz) is assigned to the phosphorus bonded to Pt. The
complex contains two PEt3 ligands bonded to Pt and one
2
2.03 (Figure 3a). The J (PtH) coupling (65 Hz) is close
to that of the corresponding hydrogen of (Cy3P)Pt(µ-η2-
SiHPh2)2Pd(PCy3) (73 Hz)6 and smaller than that of
[(Ph3P)Pt(µ-η1,η2-SiH2Ar)]2 (118 Hz).13b The 1J (SiH)
coupling (28 Hz) is much smaller than Si-H groups of
organosilanes (190-200 Hz), which is ascribed to the
Pd-H-Si three-center, two-electron bonding. The spec-
trum does not show a signal corresponding to the Si-
H-Pt hydrogen. Although a peak at δ 1.28 is close to
the Si-H-Pt hydrogen of (Cy3P)Pt(µ-η2-SiHPh2)2Pd-
(PCy3) (δ 1.70 in C6D6),6 it does not show the 195Pt
satellite signals at reasonable positions. The following
deuterium-labeling experiment provides the unambigu-
1
PEt3 bonded to Pd center at this temperature. The H
NMR spectrum at -90 °C gives rise to two signals for
(18) The 2H NMR spectrum of 2-d2 indicates the structure containing
Si-D-Pd and Si-D-Pt bonding unambiguously. The 1H NMR spec-
trum of 2 at 25 °C, however, does not exhibit a signal around the peak
position in the 2H NMR spectrum of 2-d2. The 1H NMR signal of the
Pt-H-Si hydrogen may appear at δ 1.28 as a singlet or at the position
that is overlapped with the PEt3 hydrogen peaks. Alternatively, serious
broadening of the peak may prevent the observation of it. A large
difference of the peak positions between the 1H and 2H NMR spectra
can be accounted for by the fluxional behavior of the complex.
(19) Lide, D. R., Ed. CRC Handbook of Chemistry and Physics, 75th
ed.; CRC Press: Boca Raton, 1994; pp 9-84. See ref 13b also.
(17) Braddock-Wilking, J .; Corey, J . C.; Dill, K.; Rath, N. P.
Organometallics 2002, 21, 5467.

4774 Organometallics, Vol. 23, No. 20, 2004
Yamada et al.
F igu r e 4. 1H NMR of 2 at -90 °C (400 MHz in CD2Cl2).
Sch em e 1
F igu r e 5. ORTEP drawing of 3 at the 30% ellipsoidal
level. One of the two crystallographically independent
molecules is shown. Selected bond distances (Å) and angles
(deg): Pt1-P1 2.392(8), Pt1-Si1 2.333(6), Pt1-Si2 2.357(5),
Pt1-C6 1.97(2), Si1-N1 1.74(1), Si2-C1 1.87(2), P1-Pt1-
Si1 177.4(2), P1-Pt1-Si2 96.4(3), P1-Pt1-C6 92.9(6),
Si1-Pt1-Si2 81.0(2), Si1-Pt1-C6 89.7(6), Si2-Pt1-C6
170.3(6), N1-Si1-Pt1 113.0(6), C1-Si2-Pt1 106.8(6), C1-
N1-Si1 113.4(9), C2-N1-Si1 125(1).
Sch em e 2
ligands, which were not isolated or characterized due
to the presence of a mixture of the complexes. Figure 5
shows the molecular structure of 3 determined by X-ray
crystallography.
the PCH2 hydrogens at δ 1.59 and 1.00 in a 1:2 signal
intensity (Figure 4).
A triplet signal is observed at δ -8.61 with J (HP) )
2
13 Hz. It is flanked with satellite signals due to a 195Pt
nucleus, although the satellites by 29Si are not observed.
These results indicate that the signal is ascribed to a
terminal hydride bonded to Pt rather than the Pt-H-
Si hydrogen. Thus, complex 2 has the structure C in
Chart 1 at -90 °C in CD2Cl2 and the structure A in
Chart 1 at 25 °C. Change of structures occurs reversibly,
as shown in Scheme 1. It involves conversion of the
Pt-H bond of C into the Pt-H-Si bond of A upon
raising the temperature and Si-H bond formation to
regenerate C caused by cooling the solution. Dissocia-
tion or exchange of the phosphine ligands is suggested
by the fluxional behavior of the signals. The solution at
25 °C may contain a minor amount of the complex
having two PEt3 ligands at Pd and one PEt3 at Pt also,
although fluxional behavior of the complex prevents the
characterization of the species by NMR. A dinuclear Rh
complex with hydride and bridging SiHPh ligands was
reported to be equilibrated with the complex with a
terminal SiH2Ph ligand in solution, as shown in Scheme
2.20 This kind of reaction probably involves reversible
conversion between the complex with hydrido and
silylene ligands and an intermediate having a M-H-
Si bond, as shown in Scheme 1.
An isomer of 3, having the PEt3 and isonitrile ligands
at different positions from those of 3, is not observed in
the reaction mixture.
The five-membered ring in 3 is composed of Si, C, N,
and Pt atoms. The carbon atom of the CH2 group is out
of the plane formed by the Pt, N, and two Si atoms.
Related five-membered rings containing Pt, Si, and C
have also been reported.21 The other product, 4, was
characterized by X-ray crystallography (Figure 6). A
long Pt-Pt distance (3.9058(7) Å) indicates a structure
without a Pt-Pt bond, similar to the silylene-bridged
dinuclear Pt complexes. The two Si atoms have a close
contact with a separation of 2.694(6) Å, which is slightly
longer than the distance between the Si centers of the
diplatinum complexes with bridging silylene ligands.9-11
The Pt-Si1 bond (2.385(3) Å) is longer than the Pt-
Si1* bond (2.375(4) Å) due to a difference of the trans
influence between the PEt3 and t-Bu-NC ligands.
Scheme 3 depicts a possible mechanism for the
formation of 3. The 1,1-insertion of isonitrile into a Pd-
The reaction of t-BuNC with complex 2 at room
temperature forms a mixture of (Et3P)(t-BuNC)Pt-
(SiPh2-CH2-(N-t-Bu)-SiPh2) (3) and (Et3P)(t-BuNC)Pt-
(µ-SiPh2)2Pt(PEt3)(CN-t-Bu) (4), as shown in eq 2. The
fractional crystallization of the products leads to isola-
tion of the complexes in respective yields of 14% and
63%. Reaction 2 gave Pd complexes with isonitrile
(21) Eaborn, C.; Metham, T. N.; Pidcock, A. J . Organomet. Chem.
1977, 131, 377. (b) Tanabe, M.; Yamazawa, H.; Osakada, K. Organo-
metallics 2001, 20, 4451.
(20) (a) Wang, W. D.; Eisenberg, R. J . Am. Chem. Soc. 1990, 112,
1833. (b) Wang, W. D.; Eisenberg, R. Organometallics 1992, 11, 908.

Pd-Pt Heterobimetallic Complexes
Organometallics, Vol. 23, No. 20, 2004 4775
bond into the Si-H bond of the complex.24 The reaction
in eq 2 did not give the products via insertion of
isonitrile into the Pt-Si bond, while a recent study of
the reaction of isonitrile with a phosphido-bridged Pt-
Pt dinuclear complex revealed smooth 1,1-insertion of
isonitrile into the Pt-P bond to form the product with
a four-membered ring composed of P, C, and two Pt
atoms.25
Pathways for the formation of 4 and Pd-containing
products are not clear at present, although the conver-
sion of a silyl-Pt complex into a silylene-bridged diplati-
num complex via elimination of H2 was reported
recently.13a A diplatinum complex with (µ-η2-H-SiRH)
ligands undergoes reductive elimination of H2 upon
addition of a tertiary phosphine. In reaction 2, coordina-
tion of t-BuNC to the Pt center induces Si-H bond
activation of the diphenylsilyl ligand to produce 4. The
reaction of t-BuNC with 4 does not form complex 3,
indicating that 4 is not a precursor of 3 in this reaction.
The reaction of a heterodinuclear Pt-Pd complex with
diphenylsilyl ligands produces the unexpected silaplati-
nacyclopentane containing four kinds of atoms in the
five-membered ring. Detailed studies of the reactivity
of late transition metal complexes toward insertion of
isonitrile into the Si-H or M-Si bond are of further
interest.
F igu r e 6. ORTEP drawing of 4 at the 30% ellipsoidal
level. The molecule has a crystallographic C2 symmetry
center. The atoms with asterisks are crystallographically
equivalent to those with the same number without asterisk.
Selected bond distances (Å) and angles (deg): Pt1‚‚‚Pt1*
3.9058(7), Pt1-P1 2.325(4), Pt1-Si1 2.385(3), Pt1-Si1*
2.375(4), Pt1-C1 1.97(2), Si‚‚‚Si 2.694(6), N1-C1 1.19(2),
N1-C2 1.44(2), P1-Pt1-Si1 168.7(2), P1-Pt1-Si1
100.3(1), P1-Pt1-C1 97.1(4), Si1-Pt1-C1 92.9(4), Si1*-
Pt1-C1 159.8(4), Si1-Pt1-Si1* 68.9(1), C1-N1-C2 171(1),
Pt1-C1-N1 175(1).
Sch em e 3
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
argon or nitrogen atmosphere. Hexane and toluene were
distilled from sodium benzophenone ketyl and stored under
nitrogen. 1H, 2H, 13C{1H}, and 31P{1H} NMR spectra were
recorded using J EOL GX-500, J EOL EX-400, and Varian
Mercury 300 spectrometers. The peak positions in the 31P{1H}
NMR spectra were referenced to external 85% H3PO4. Pt-
(SiHPh2)2(PEt3)226 and Pd(PEt3)327 were prepared according to
the literature. tert-Butylisocyanide was obtained from com-
mercial suppliers and used as received. IR absorption spectra
were recorded with Shimadzu FT/IR-8100 spectrometers.
Elemental analyses were carried out with a Yanaco MT-5 CHN
autocorder.
P r ep a r a tion of (P Et3)P t(µ-η2-HSiP h 2)2P d (P Et3) (1) a n d
(P Et3)2P t(µ-η2-HSiP h 2)2P d (P Et3) (2). A toluene (8 mL) solu-
tion containing Pd(PEt3)3 (290 mg, 0.70 mmol) and Pt-
(SiHPh2)2(PEt3)2 (550 mg, 0.70 mmol) was stirred at room
temperature for 4 h. The solvent was evaporated under
reduced pressure, and the formed residue was dissolved in
hexane (10 mL). Keeping the solution for 1 day at 25 °C caused
separation of complex 1 as pale yellow crystals (205 mg, 34%).
After removing 1 by filtration, the solvent of the filtrate was
reduced to approximately 5 mL under reduced pressure and
cooled at -30 °C. After 1 week, orange crystals of 2 were
separated from the solution and were collected by filtration
(179 mg, 25%).
Si bond forms a four-membered ring composed of Pt,
Pd, C, and Si atoms. Subsequent transfer of the hydro-
gen bonded to Pt to the imine carbon leads to a Pt-Pd
heterobimetallic intermediate with the iminosilyl ligand
bonded to the Pt center via the Si atom. Further
insertion of the CdN double bond into the Pd-H bond
and reductive elimination of the aminosilane takes
place. Addition of a Si-H bond in a Si ligand bonded to
Fe and Pt to a CN triple bond was reported in the
reaction of nitriles with the mononuclear complexes of
these metals.22 Similar addition of a Si-H bond in a
Ru complex to an alkene was recently reported in the
mechanistic study of hydrosilylation catalyzed by Ru.23
Reaction of acetone with a tungsten complex having a
dCH(C(SiMe3)3) ligand also causes insertion of the CdO
Da ta for 1. Anal. Calcd for C36H52P2PdPtSi2: C, 47.81; H,
1
5.80. Found: C, 47.68; H, 5.53. H NMR (400 MHz, C6D6, 25
°C): δ 8.20 (d, 1H, C6H5-o, J (HH) ) 8 Hz), 8.08 (d, 3H, C6H5-
o, J (HH) ) 8 Hz), 8.06 (d, 3H, C6H5-o, J (HH) ) 8 Hz), 8.01 (d,
1H, C6H5-o, J (HH) ) 8 Hz), 7.32 (t, 4H, C6H5-m, J (HH) ) 8
Hz), 7.28 (t, 4H, C6H5-m, J (HH) ) 7 Hz), 7.18 (t, 4H, C6H5-p,
(24) Watanabe, T.; Hashimoto, H.; Tobita, H. Angew. Chem., Int.
Ed. 2004, 43. 218.
(22) (a) Corriu, R. J . P.; Moreau, J . J . E.; Pataud-Sat, M. Organo-
metallics 1985, 4, 623. (b) Tanabe, M.; Osakada, K. Organometallics
2001, 20, 2118. See also: Murai, T.; Sakane, T.; Kato, S. Tetrahedron
Lett. 1985, 26, 5145.
(25) Cristofani, S.; Leoni, P.; Pasquali, M.; Eisentraeger, F.; Albinati,
A. Organometallics 2000, 19, 4589.
(26) Kim, Y.-J .; Park, J .-I.; Lee, S.-C.; Osakada, K.; Tanabe, M.; Choi,
J .-C.; Koizumi, T.; Yamamoto, T. Organometallics 1999, 18, 1349.
(27) Schunn, R. A. Inorg. Chem. 1976, 15, 208.
(23) Glaser, P. B.; Tilley, T. D. J . Am. Chem. Soc. 2003, 125, 13640.

4776 Organometallics, Vol. 23, No. 20, 2004
Ta ble 1. Cr ysta llogr a p h ic Da ta a n d Deta ils of Refin em en t
Yamada et al.
1
2
3
4
chemical formula
fw
cryst syst
space group
a, Å
C
36H50P2PdPtSi2
C42H65P3PdPtSi2
1020.56
triclinic
P1h (No. 2)
11.8945(5)
20.3726(8)
21.3757(7)
65.69(1)
73.11(2)
78.03(2)
4494.1(3)
4
C40H55N2PPtSi2
846.12
C46H68N2Si2P2Pt2
1157.36
monoclinic
C2/c (No. 15)
19.222(5)
902.40
triclinic
P1h (No. 2)
9.6294(7)
10.1484(5)
11.3224(1)
78.89(3)
68.03(3)
64.21(2)
923.27(8)
1
triclinic
P1 (No. 1)
11.787(3)
12.124(3)
17.936(6)
73.20(2)
81.52(2)
58.98(1)
2102.8(10)
2
b, Å
c, Å
11.727(2)
22.376(5)
R, deg
â, deg
106.47(1)
γ, deg
V, Å3
4836.7(20)
4
5.902
2288
Z
µ, mm-1
F(000)
4.431
450
1.627
3.684
2056
1.508
3.445
860
1.336
D
calcd, g cm-3
1.589
cryst size, mm × mm × mm
0.50 × 0.50 × 0.50
0.55 × 0.32 × 0.25
0.30 × 0.15 × 0.10
0.20 × 0.15 × 0.10
no. of unique reflns
5206
18 826
8664
5445
3397
278
no. of reflns used (I>3.0σ(I))
no. of variables
5075
215
13 764
1021
6656
859
R
Rw
GOF
0.044
0.071
1.13
0.066
0.081
2.17
0.043
0.053
0.989
0.044
0.073
0.096
J (HH) ) 8 Hz), 2.71 (d, 1H, Pd-H-Si, 2J (HPt) ) 96 Hz, 2J (HP)
) 13 Hz), 2.06 (d, 1H, Pt-H-Si, 1J (HPt) ) 650 Hz, 2J (HP) ) 13
Hz), 1.49 (m, 6H, PCH2), 1.27 (apparent quintet due to virtual
coupling, 6H, PCH2), 0.71 (m, 18H, PCH2CH3). 13C{1H} NMR
(100 MHz, CD2Cl2, 25 °C): δ 147.1 (s, C6H5-i), 144.7 (s, C6H5-
i), 136.4 (s, C6H5-o), 136.1 (s, C6H5-o), 128.5 (s, C6H5-m), 128.1
(s, C6H5-p), 127.6 (s, C6H5-m), 22.2 (d, PCH2, 1J (CP) ) 29 Hz),
mg, 63%). The combined filtrate and washings were stored for
3 days at -30 °C to form a white solid, which was collected by
filtration to give 3 (15 mg, 14%). Data for 3: Anal. Calcd for
C40H55N2PPtSi2: C, 56.78; H, 6.55; N, 3.31. Found: C, 56.35;
1
H, 6.34; N, 2.88. H NMR (400 MHz, C6D6, rt): δ 8.10 (d, 4H,
C6H5-o, J (HH) ) 8 Hz), 7.96 (d, 4H, C6H5-o, J (HH) ) 8 Hz),
7.33 (t, 4H, C6H5-m, J (HH) ) 8 Hz), 7.32 (t, 4H, C6H5-m, J (HH)
) 8 Hz), 7.24 (t, 2H, C6H5-p, J (HH) ) 8 Hz), 7.18 (t, 2H, C6H5-
1
20.8 (d, PCH2, J (CP) ) 20 Hz), 9.0 (s, CH3), 8.9 (s, CH3). 31P-
1
{1H} NMR (162 MHz, CD2Cl2, 25 °C): δ 28.3 (d, Pt-P, J (PPt)
3
p, J (HH) ) 8 Hz), 3.55 (s, 2H, CH2, J (HPt) ) 41 Hz), 1.24 (s,
3
2
) 3556 Hz, J (PP) ) 55 Hz), 15.8 (d, Pd-P, J (PPt) ) 258 Hz,
9H, Si-NC(CH3)3), 1.22 (m, 6H, PCH2CH3), 0.76 (s, 9H,
Pt-CNC(CH3)3), 0.64 (m, 9H, PCH2CH3). 13C{1H} NMR (126
MHz, C6D6, rt): δ 149.9 (s, C6H5-i), 145.9 (s, C6H5-i), 137.3 (s,
3J (PP) ) 55 Hz).
Da ta for 2. Anal. Calcd for C42H67P3PdPtSi2: C, 49.33; H,
6.60. Found: C, 49.73; H, 6.07. 1H NMR (400 MHz, CD2Cl2,
25 °C): δ 7.70 (d, 4H, C6H5-o), 7.68 (d, 4H, C6H5-o, J (HH) ) 6
Hz), 7.31 (t, 4H, C6H5-m, J (HH) ) 6 Hz), 7.28 (t, 4H, C6H5-m,
J (HH) ) 6 Hz), 7.26 (t, 4H, C6H5-p, J (HH) ) 6 Hz), 2.03 (s,
2
2
C6H5-o, J (CPt) ) 15 Hz), 136.2 (s, C6H5-o, J (CPt) ) 15 Hz),
127.3 (s, C6H5-m), 126.9 (s, C6H5-m), 56.4 (s, C(CH3)3), 54.4 (s,
C(CH3)3, 3J (CPt) ) 22 Hz), 45.7 (d, CH2, 3J (CP) ) 8 Hz, 2J (CPt)
) 107 Hz), 30.7 (s, C(CH3)3), 29.4 (s, C(CH3)3), 18.7 (d, PCH2,
2J (CP) ) 22 Hz, 3J (CPt) ) 42 Hz), 8.6 (s, PCH2CH3, 3J (CPt) )
18 Hz). The signals of C6H5-p are overlapped with solvent
2
1
1H, Pd-H-Si, J (HPt) ) 65 Hz, J (HSi) ) 28 Hz), 1.28 (s, 1H,
see Results and Discussion), 1.50 (br, 18H, PCH2), 0.87 (br,
1
1
signals. 31P{1H} NMR (162 MHz, C6D6, rt): δ 18.1 (s, J (PPt)
27H, CH3). H NMR (400 MHz, CD2Cl2, -90 °C): δ 7.54 (br,
) 1545 Hz). IR (KBr, cm-1): 2157 ν(CN).
8H, C6H5-o), 7.20 (br, 8H, C6H5-m, J (HH) ) 5 Hz), 7.14 (br,
4H, C6H5-p), 1.59 (br, 6H, PCH2), 1.00 (m, 12H, PCH2), 0.48
Da ta for 4. Anal. Calcd for C46H68N2P2Pt2Si2: C, 47.74; H,
5.92; N, 2.42. Found: C, 47.89; H, 5.98; N, 2.43. 1H NMR (400
MHz, C6D6, rt): δ 8.16 (d, 8H, C6H5-o), 7.27 (t, 8H, C6H5-m),
7.12 (t, 4H, C6H5-p), 1.38 (dq, 12H, PCH2CH3, 2J (HP) ) 8 Hz),
0.91 (s, 18H, C(CH3)3), 0.88 (dt, 18H, PCH2CH3, 3J (HP) ) 8
Hz). 13C{1H} NMR (100 MHz, C6D6, rt): δ 152.5 (s, C6H5-i),
137.9 (s, C6H5-o, 3J (CPt) ) 26 Hz), 126.2 (s, C6H5-m), 125.7 (s,
C6H5-p), 55.6 (s, C(CH3)3), 29.8 (s, C(CH3)3), 19.7 (m, PCH2-
1
2
(br, 27H, CH3), -8.61 (t, 1H, Pt-H, J (HPt) ) 550 Hz, J (HP)
) 13 Hz). 13C{1H} NMR (100 MHz, CD2Cl2, -90 °C): δ 150.8
(s, C6H5-i), 146.6 (s, C6H5-i), 134.6 (s, C6H5-o), 126.7 (s, C6H5-
p), 126.5 (s, C6H5-m), 126.0 (s, C6H5-m), 20.9 (br, Pt-PCH2),
19.2 (d, Pd-PCH2), 8.3 (s, Pd-PCH2CH3), 7.9 (s, Pt-PCH2CH3).
31P{1H} NMR (162 MHz, CD2Cl2, 25 °C): δ 5.2 (br). 31P{1H}
NMR (162 MHz, CD2Cl2, -90 °C): δ 7.2 (t, Pd-P, 2J (PPt) )
3
1
243 Hz, J (PP) ) 27 Hz), -0.96 (d, Pt-P, J (PPt) ) 3223 Hz,
2
3
CH3, J (CPt) ) 36 Hz), 8.89 (s, PCH2CH3, J (CPt) ) 16 Hz).
3J (PP) ) 27 Hz).
31P{1H} NMR (162 MHz, C6D6, rt): δ 24.4 (s, J (PPt) ) 1495
1
P r ep a r a tion of (P Et3)P t(µ-η2-DSiP h 2)2P d (P Et3) (1-d 2)
a n d (P Et3)2P t(µ-η2-DSiP h 2)2P d (P Et3) (2-d 2). These com-
plexes were prepared by using D2SiPh2 analogously. 2H NMR
of 1-d2 (77 MMHz, C6H6-C6D6, 25 °C): δ 2.74 (s, Pd-D-Si,
2J (DPt) ) 15 Hz), 2.07 (s, Pt-D-Si, 1J (DPt) ) 90 Hz). 2H NMR
of 2-d2 (77 MHz, C6H6-C6D6, 25 °C): δ 2.51 (s, Pd-D-Si, 2J (DPt)
) 11 Hz), -0.29 (br, Pt-D-Si, 1J (DPt) ) 96 Hz); (77 MHz, CH2-
Cl2-CD2Cl2, 25 °C): δ 2.15 (s, Pd-D-Si, 2J (DPt) ) 10 Hz), 0.41
Hz, J (PPt) ) 245 Hz, J (PP) ) 32 Hz). IR (KBr, cm-1): 2132
3
4
ν(CN).
X-r a y Cr ysta llogr a p h y. Crystals of 1-4 suitable for X-ray
diffraction studies were mounted in glass capillaries under
argon. Data were collected at -180 °C on a Rigaku Saturn
CCD area detector equipped with graphite-monochromated Mo
KR radiation (λ ) 0.71073 Å). A total of 720 oscillation images
were collected. A sweep of data was done using ω scans from
-110.0° to 70.0° in 0.5° step, at ø ) 45.0° and φ ) 0.0°. The
detector swing angle was -20.32°. The crystal-to-detector
distance was 45.00 mm. Readout was performed in the 0.070
mm pixel mode. Calculations were carried out by using the
program package Crystal Structure for Windows. The struc-
ture was solved by direct methods and expanded using Fourier
techniques. A full-matrix least-squares refinement was used
for the non-hydrogen atoms with anisotropic thermal param-
1
(br, Pt-D-Si, J (DPt) ) 106 Hz).
P r ep a r a tion of P t(SiP h 2-CH2-NC(CH3)3-SiP h 2)(CNC-
(CH3)3)(P Et3) (3) a n d [(Et3P )P t(µ-SiP h 2)(CNC(CH3)3)]2 (4).
To a hexane (5 mL) solution of 2 (250 mg, 0.24 mmol) was
added tert-butylisocyanide (58 µL, 0.51 mmol) at room tem-
perature. After stirring the reaction mixture for 4 h a yellow
solid was precipitated. The solid was collected by filtration,
washed with hexane (2 mL), and dried in vacuo to give 4 (90

Pd-Pt Heterobimetallic Complexes
Organometallics, Vol. 23, No. 20, 2004 4777
eters. Crystallographic data and details of structure refine-
ment are summarized in Table 1.
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
data of 1-4. This material is available free of charge via the
Internet at http://pubs.acs.org.
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for Scientific Research from the Ministry
of Education, Science, Sports, and Culture, J apan.
OM049858D