Oxidative addition of silicon-halogen bonds to platinum(0) complexes and reactivities of the resulting silylplatinum species

Article abstract of DOI:10.1021/om970214y

Oxidative addition of the silicon-halogen bonds of halosilanes R₃Si-X (X = Cl, Br, I) to platinum(0) complexes PtL_n (L = tertiary phosphine) yielded trans-R₃SiPtXL₂ species. Halosilanes exhibited the following orders of reactivities: for Me₃SiX, X = Cl (no reaction) < Br < I, and for Me_4-nSiCl_n, n = 1 (no reaction) < <2 < 3. The reactivities of platinum complexes increased in the order of Pt(PPh₃)₄, Pt[Ph₂P(CH₂)₂PPh₂]₂ (no reactions) < < Pt(PMe₂Ph)₄ < Pt(PMe₃)₄ < Pt(PEt₃)₄. Coordinately unsaturated Pt(PEt₃)₃ was more reactive than Pt(PEt₃)₄. Me₃SiSiMe₂I also underwent addition at the Si-I bond to Pt(PEt₃)₃ with the Si-Si bond being intact to form trans-Me₃SiMe₂SiPtI(PEt₃)₂. Treatment of trans-Me₃SiPtBr(PEt₃)₂ (2a) with a phosphine (PEt₃, PPh₃) resulted in reductive elimination of Me₃SiBr. The reaction of 2a with styrene gave PhCH=CHSiMe₃, although the major part of the Me₃Si moiety was eliminated as Me₃SiBr. Silyl group exchange of 2a or trans-Me₃-SiPtI(PEt₃)₂ cleanly took place upon treatment with the hydrosilane R₃SiH (Me₂PhSiH, MePhSiH₂) to provide trans-R₃SiPtX(PEt₃)₂ (X = Br, I). Transmetalation between 2a and Et₂Zn or Ph₂Hg respectively yielded Me₃SiEt or Me₃SiPh in a smooth reaction. ¹H, ¹³C, ²⁹Si, ³¹P, and ¹⁹⁵Pt NMR spectra of the resulting silylplatinum species are discussed in terms of the trans and cis influences and the electronegativity of the ligated groups.

Full text of DOI:10.1021/om970214y

4696
Organometallics 1997, 16, 4696-4704
Oxid a tive Ad d ition of Silicon -Ha logen Bon d s to
P la tin u m (0) Com p lexes a n d Rea ctivities of th e Resu ltin g
Silylp la tin u m Sp ecies
Hiroshi Yamashita, Masato Tanaka,* and Midori Goto
National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305, J apan
Received March 17, 1997X
Oxidative addition of the silicon-halogen bonds of halosilanes R3Si-X (X ) Cl, Br, I) to
platinum(0) complexes PtLn (L ) tertiary phosphine) yielded trans-R3SiPtXL2 species.
Halosilanes exhibited the following orders of reactivities: for Me3SiX, X ) Cl (no reaction)
<< Br < I, and for Me4-nSiCln, n ) 1 (no reaction) << 2 < 3. The reactivities of platinum
complexes increased in the order of Pt(PPh3)4, Pt[Ph2P(CH2)2PPh2]2 (no reactions) <<
Pt(PMe2Ph)4 < Pt(PMe3)4 < Pt(PEt3)4. Coordinately unsaturated Pt(PEt3)3 was more reactive
than Pt(PEt3)4. Me3SiSiMe2I also underwent addition at the Si-I bond to Pt(PEt3)3 with
the Si-Si bond being intact to form trans-Me3SiMe2SiPtI(PEt3)2. Treatment of trans-
Me3SiPtBr(PEt3)2 (2a ) with a phosphine (PEt3, PPh3) resulted in reductive elimination of
Me3SiBr. The reaction of 2a with styrene gave PhCHdCHSiMe3, although the major part
of the Me3Si moiety was eliminated as Me3SiBr. Silyl group exchange of 2a or trans-Me3-
SiPtI(PEt3)2 cleanly took place upon treatment with the hydrosilane R3SiH (Me2PhSiH,
MePhSiH2) to provide trans-R3SiPtX(PEt3)2 (X ) Br, I). Transmetalation between 2a and
Et2Zn or Ph2Hg respectively yielded Me3SiEt or Me3SiPh in a smooth reaction. 1H, 13C,
29Si, 31P, and 195Pt NMR spectra of the resulting silylplatinum species are discussed in terms
of the trans and cis influences and the electronegativity of the ligated groups.
In tr od u ction
complexes. We have already disclosed that oxidative
addition of silicon-halogen (I, Br, and Cl) bonds to plati-
num(0) complexes proceeds to give the corresponding
halogeno(silyl)platinum complexes.8 Herein are re-
ported the details of the reaction, including the reac-
tivities and the NMR spectra of the resulting silylplat-
inum species.
Organosilane, organogermane, and organostannane
compounds have attracted growing interest for their
utility as versatile synthetic reagents and for their
intriguing physicochemical properties, especially those
of relevant polymers.1 In this context, new efficient
catalyses to prepare or to transform these heteroatom
compounds are increasingly required, considering the
important role played by catalytic reactions for the
advancement of organic chemistry in the past decades.
For the development of new catalyses, oxidative addition
of these group 14 element-halogen bonds to transition
metals is one of the most important key elemental
reactions, since it offers the possibility of realizing a
variety of catalytic reactions similar to those of organic
halides that are widely used in organic synthesis.2
However, the reactivities of silicon, germanium, and tin
halides toward transition-metal complexes have not
been fully elucidated as yet.3 To our knowledge, unequi-
vocal examples of oxidative addition have been limited
to those of some silicon-halogen bonds toward iridium4-6
or platinum7-9 complexes and some germanium-
halogen9-11 or tin-halogen9,12-14 bonds toward platinum
(3) For some reviews on the reactivities of silicon, germanium, and/
or tin compounds toward metal complexes, see: (a) Mackay, K. M.;
Nicholson, B. K. In Comprehensive Organometallic Chemistry; Wilkin-
son, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon: Oxford, U.K.,
1982; Chapter 43. (b) Aylett, B. J . Adv. Inorg. Chem. Radiochem. 1982,
25, 1. (c) Schubert, U. Transition Met. Chem. 1991, 16, 136. (d) Tilley,
T. D. In The Silicon-Heteroatom Bond; Patai, S., Rappoport, Z., Eds.;
Wiley: Chichester, U.K., 1991; Chapters 9 and 10.
(4) (a) Uson, R.; Oro, L. A.; Fernandez, M. J . J . Organomet. Chem.
1980, 193, 127. (b) Uson, R.; Oro, L. A.; Ciriano, M. A.; Gonzalez, R. J .
Organomet. Chem. 1981, 205, 259.
(5) Zlota, A. A.; Frolow, F.; Milstein, D. J . Chem. Soc., Chem.
Commun. 1989, 471.
(6) Yamashita, H.; Kawamoto, A. M.; Tanaka, M.; Goto, M. Chem.
Lett. 1990, 2107.
(7) Clark, H. C.; Hampden-Smith, M. J . Coord. Chem. Rev. 1987,
79, 229.
(8) (a) Yamashita, H.; Kobayashi, T.; Hayashi, T., Tanaka, M.; Goto,
M. J . Am. Chem. Soc. 1988, 110, 4417. (b) Yamashita, H.; Kobayashi,
T.; Hayashi, T.; Tanaka, M. Chem. Lett. 1990, 1447. (c) Yamashita,
H.; Hayashi, T.; Tanaka, M. J pn. Kokai Tokkyo Koho, J P 89-294685
(to Agency of Industrial Science and Technology, J apan), 1989; Chem.
Abstr. 1990, 113, 24235h.
X Abstract published in Advance ACS Abstracts, September 15, 1997.
(1) (a) The Chemistry of Organic Silicon Compounds; Patai, S.,
Rappoport, Z., Eds.; Wiley: Chichester, U.K., 1989. (b) Rive´re, P.;
Rive´re-Baudet, M.; Satge´, J . In Comprehensive Organometallic Chem-
istry; Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon:
Oxford, U.K., 1982; Chapter 10. (c) Davies, A. G.; Smith, P. J . In
Comprehensive Organometallic Chemistry; Wilkinson, G., Stone, F. G.
A., Abel, E. W., Eds.; Pergamon: Oxford, U.K., 1982; Chapter 11.
(2) For instance, see: Collman, J . P.; Hegedus, L. S.; Norton, J . R.;
Fink, R. G. Principles and Application of Organotransition Metal
Chemistry; University Science Books: Mill Valley, CA, 1987; p 681,
and references cited therein.
(9) (a) Levy, C. J .; Puddephatt, R. J .; Vittal, J . J . Organometallics
1994, 13, 1559. (b) Levy, C. J .; Vittal, J . J .; Puddephatt, R. J .
Organometallics 1996, 15, 2108.
(10) Kuyper, J . Inorg. Chem. 1978, 17, 77.
(11) Yamashita, H.; Kobayashi, T.; Tanaka, M.; Samuels, J . A.;
Streib, W. E. Organometallics 1992, 11, 2330.
(12) (a) Eaborn, C.; Pidcock, A.; Steele, B. R. J . Chem. Soc., Dalton
Trans. 1976, 767. (b) Butler, G.; Eaborn, C.; Pidcock, A. J . Organomet.
Chem. 1978, 144, C23.
(13) Kuyper, J . Inorg. Chem. 1977, 16, 2171.
(14) Albano, V. G.; Castellari, C.; Monari, M.; De Felice, V.; Panunzi,
A.; Ruffo, F. Organometallics 1996, 15, 4012.
S0276-7333(97)00214-8 CCC: $14.00 © 1997 American Chemical Society

Addition of Si-Halogen Bonds to Pt(0) Complexes
Organometallics, Vol. 16, No. 21, 1997 4697
Ta ble 1. Rea ction s of P la tin u m (0) Com p lexes w ith Ha losila n esa
complex
halosilane
temp (°C)
time
15 h
15 h
1 h
4 h
15 h
4 h
∼5 min
15 h
15 h
15 h
1 h
15 min
18 h
1 h
product
yieldb (%)
Pt(PPh3)4 (1a )
Pt(dppe)2c (1b)
Pt(PEt3)4 (1c)
Me3SiX (X ) Cl, Br, I)
Me3SiX (X ) Cl, Br, I)
Me3SiBr
120
120
90
no reactn
no reactn
trans-Me3SiPtBr(PEt3)2 (2a )
∼35
∼65
2a
2a
2a
∼80
Pt(PEt3)3 (1d )
Me3SiBr
Me3SiI
Me3SiCl
MePh2SiCl
Ph3SiCl
Me2SiCl2
MeSiCl3
Me3SiBr
90
90
∼95
trans-Me3SiPtI(PEt3)2 (2b)
no reacn
∼100
120
120
120
120
90
120
90
120
120
90
no reacn
no reacn
trans-Me2ClSiPtCl(PEt3)2 (2c)
trans-MeCl2SiPtCl(PEt3)2 (2d )
trans-Me3SiPtBr(PMe3)2 (2e)
trans-Me3SiPtI(PMe3)2 (2f)
no reacn
∼90
∼100
∼50
Pt(PMe3)4 (1e)
Me3SiI
Me3SiX (X ) Cl, Br)
Me3SiI
∼90
Pt(PMe2Ph)4 (1f)
15 h
13 h
10 min
trans-Me3SiPtI(PMe2Ph)2 (2g)
trans-Me3SiMe2SiPtI(PEt3)2 (2h )
∼70
1d
Me3SiSiMe2I
∼100
Conditions: complex (0.075-0.30 mmol, ca. 0.4-0.5 M), halosilane (∼3 equiv), benzene-d6 (0.20-0.60 mL). Estimated by 1H NMR.
a
b
c dppe ) Ph2P(CH2)2PPh2.
Resu lts a n d Discu ssion
nearly quantitatively by heating at 90 °C for ∼5 min.
In a separate reaction at 80 °C for 50 min, 2b could be
isolated in 82% yield after recrystallization from pen-
tane. In contrast with Me3SiX (X ) Br, I), no reactions
took place between 1d and monochlorosilanes such as
Me3SiCl, MePh2SiCl, and Ph3SiCl (heating up to 120
°C). The dichlorosilane Me2SiCl2, however, could react
at the Si-Cl bond to give trans-Me2ClSiPtCl(PEt3)2 (2c)
in ∼90% NMR yield (120 °C, 1 h). In addition, the more
chlorinated halosilane MeSiCl3 underwent the addition
to 1d at a much higher rate to give trans-MeCl2SiPtCl-
(PEt3)2 (2d ) in ∼100% NMR yield (90 °C, 15 min).17
Noteworthy is that activation of the Si-Cl bonds of
industrially produced chlorosilanes was achieved under
relatively mild conditions. In separate reactions under
similar conditions, reasonably pure 2c and 2d were
easily obtained by removal of volatiles from the reaction
mixtures in vacuo. Silyl species 2b-d were identified
Rea ction s of P la tin u m (0) Com p lexes w ith Si-X
(X ) Cl, Br , I) Bon d s. The reaction of a platinum(0)
complex with a halosilane (ca. 3 equiv) was carried out
in a sealed NMR tube using benzene-d6 or benzene as
solvent. The progress of the reaction was monitored by
means of H and/or 31P NMR. As summarized in eq 1
1
1
by H, 13C, 29Si, 31P, and 195Pt NMR (vide infra) and IR
and Table 1, the reactions of Pt(PPh3)4 (1a ) or Pt(dppe)2
(1b; dppe ) Ph2P(CH2)2PPh2) with Me3SiX (X ) Cl, Br,
I) did not afford any silylplatinum species even under
forcing conditions (heating up to 120 °C for 15 h).
However, when Pt(PEt3)4 (1c) was treated with Me3-
SiBr at 90 °C for 1 h, a new Me3Si proton signal
ascribable to trans-Me3SiPtBr(PEt3)2 (2a ) emerged at
0.42 ppm (3J PtH ) 25.4 Hz). The yield of 2a was
estimated at ∼35% by 1H NMR. The product appeared
stable in the presence of excess halosilane, and prolong-
ing the reaction time increased the yield of 2a to ∼65%
(total heating time 4 h) and ∼80% (15 h). Coordinately
unsaturated Pt(PEt3)3 (1d ) showed much higher reac-
tivity than 1c, and 2a was formed in ∼95% NMR yield
after heating at 90 °C for 4 h. In a separate larger scale
reaction of 1d with Me3SiBr (120 °C, 7 h), 2a could be
isolated as yellow needles in 59% yield after recrystal-
lization from pentane. Its NMR and IR spectra and
elemental analysis were quite consistent with the
proposed structure. The NMR and IR spectra were
similar to those of the known complex trans-Me3SiPtCl-
(PEt3)2, which was prepared separately by the reaction
of cis-PtCl2(PEt3)2 with (Me3Si)2Hg.15 The structure of
2a was finally confirmed by X-ray diffraction analysis.8a,16
Thus, oxidative addition of the Me3Si-Br bond to 1c or
1d was unequivocally verified to proceed.
and/or elemental analysis.
Besides the PEt3 complexes 1c,d , Pt(PMe3)4 (1e) also
reacted with Me3SiBr to give the corresponding silyl-
platinum species trans-Me3SiPtBr(PMe3)2 (2e), although
1e was much less reactive than 1c; the NMR yield of
2e was ∼50% (120 °C, 18 h), while the yield of 2a in
the reaction of 1c was ∼80% (90 °C, 15 h). The reaction
of 1e with Me3SiI proceeded more readily, as in the
reaction of 1d , to form trans-Me3SiPtI(PMe3)2 (2f) in
∼90% yield (90 °C, 1 h). In addition, Pt(PMe2Ph)4 (1f)
reacted with Me3SiI at 120 °C over 13 h to give trans-
Me3SiPtI(PMe2Ph)2 (2g) in ∼70% yield, whereas 1f did
not react with Me3SiBr up to 120 °C. For species 2e-
(15) (a) Glockling, F.; Hooton, K. A. J . Chem. Soc. A 1967, 1066.
Generally, R3SiPtXL2 (X ) halogen, L ) phosphine) species were
prepared by treating PtX2L2 with R3SiLi or with R3SiH and Et3N or
by treating PtHXL2 with R3SiH. For instance, see: (b) Chatt, J .;
Eaborn, C.; Ibekwe, S. D.; Kapoor, P. N. J . Chem. Soc. A 1970, 1343
and references cited therein. (c) Ebsworth, E. A. V.; Edward, J . M.;
Rankin, D. W. H. J . Chem. Soc., Dalton Trans. 1976, 1673 and
references cited therein.
(16) The silicon atom coordinates to the platinum atom directly. The
coordination geometry around the platinum atom is that of a square
plane, and the phosphine ligands are located at positions trans to each
other. The accuracy in the X-ray analysis was not particularly high
but was sufficient to elucidate these important structural character-
istics. The crystallographic parameters have been deposited with the
Cambridge Crystallographic Data Centre; REFCODE:GETPIE.
(17) Clark et al. briefly mentioned the formation of trans-(PhCl2-
Si)PtCl(PCy3)2 (Cy ) cyclohexyl) by oxidative addition of PhSiCl3 to
Pt(PCy3)2, although no experimental details were given.7
The iodosilane Me3SiI reacted with 1d much more
readily than Me3SiBr to give trans-Me3SiPtI(PEt3)2 (2b)

4698 Organometallics, Vol. 16, No. 21, 1997
Yamashita et al.
g, pure samples have not been obtained because of the
difficulty of removing unidentified phosphorus-contain-
ing impurities and/or separating the products from the
unreacted starting complexes. However, NMR observa-
tions evidenced the identity of species 2e-g. Thus,
Me3SiX (X ) I, Br) undergo oxidative addition at the
silicon-halogen bonds with silicon-carbon bonds intact.
The reaction manners of Me2SiCl2 and MeSiCl3 are
similar to those of Me2SnX2 (X ) Br, Cl) and MeSnCl3,
manifesting the preferential formation of E-Pt-X (E
) Si, Sn; X ) Br, Cl) species.
1
relatively pure 2e-g clearly displayed the H, 13C, and
29Si NMR signals of the M3Si-Pt moieties with expected
coupling patterns (vide infra). In addition, 31P and 195Pt
NMR of 2e-g at low temperatures (-20 to -60 °C)
unambiguously revealed the existence of trans-bis-
(phosphine)platinum structures, although those reso-
nances were significantly broadened at room tempera-
ture, presumably because of the phosphorus-containing
impurities.
For the reactivities of halosilanes toward palladium-
(0) or platinum(0) complexes, it was reported that Me3-
23
SiCl reacted with 1b22 or Pd(PPh3)4 to provide a
disilane (Me3SiSiMe3) along with the corresponding
metal dichloride (PtCl2(dppe) or PdCl2(PPh3)2). The
disilane might be formed via sequential reactions of the
2 equiv of the Me3Si-Cl bond with the metal species.
However, formation of disilanes was not observed in the
foregoing reactions.
The geometry of the silylplatinum species obtained
in the foregoing reactions was determined to be trans,
In addition to halomonosilanes, an iododisilane, Me3-
SiSiMe2I, also reacted with 1d at the Si-I bond to give
trans-Me3SiMe2SiPtI(PEt3)3 (2h ) nearly quantitatively
(90 °C, 10 min; eq 2, Table 1). In a separate reaction
1
as judged from the relatively large values of J PtP
ranging from 2516 to 2914 Hz (vide infra).18 In the case
of 2a , the trans structure was determined by X-ray
crystallography.8a,16 The preference for the trans ge-
ometry is the same as in the oxidative addition of
carbon-halogen bonds to zerovalent phosphine com-
plexes of group 10 metals.19
On the basis of the reaction conditions and the NMR
yields of the silylplatinum species (Table 1), the reac-
tivities of silicon-halogen bonds are estimated to in-
crease in the following order: for Me3SiX, X ) Cl (no
reaction) << Br < I, and for Me4-nSiCln, n ) 1 (no
reaction) << 2 < 3. The trend of the reactivity in the
series of Me3SiX seems to reflect the dissociation ener-
gies of the Me3Si-X bonds (98, 76, and 57 kcal/mol for X
) Cl, Br, and I, respectively20); halosilanes with weaker
silicon-halogen bonds are more favorable for the oxida-
tive addition. On the other hand, the reactivities of
platinum(0) complexes increased in the order of L )
PPh3, dppe (no reactions) << PMe2Ph < PMe3 < PEt3.
The order for monodentate phosphines is the reverse of
that of the electronic parameters (ν)21 of phosphines (ν
) 2068.9, 2065.3, 2064.1, and 2061.7 for PPh3, PMe2-
Ph, PMe3, and PEt3, respectively); electron-donating
phosphines enhance the susceptivity to the oxidative
addition. This indicates that the reaction proceeds via
electrophilic interaction of halosilanes with platinum-
(0) complexes. The dissociation of the phosphine L from
PtL4 also seems to be a crucial step, since the coordi-
nately unsaturated 1d exhibited significantly higher
reactivity than 1c.
(60 °C, 1 h), 2h was obtained as yellow cubic crystals
in 68% yield by recrystallization from pentane. The
isolated 2h showed satisfactory NMR (vide infra), IR,
and analytical data. As we reported previously, other
halogenated disilanes, such as XMe2SiSiMe2Y for (X, Y)
) (F, F), (Cl, Cl), (Cl, Me), and (Br, Me), underwent the
selective cleavage of the Si-Si bonds with the silicon-
halogen bonds intact to provide cis-(XMe2Si)(YMe2Si)-
Pt(PEt3)2 species.8b The reactivities of halodisilanes
seem to be associated with the dissociation energies of
the Me3Si-X bonds (57, 68, 76, 98, and 141 kcal/mol
for X ) I, SiMe3, Br, Cl, and F);20 weaker bonds are more
reactive for the oxidative addition. Complex 2h was
stable in benzene-d6 solution for at least several weeks
at room temperature. However, when the solution stood
(in a sealed NMR tube) for 2.5 years, decomposition of
2h into 2b occurred (g80% NMR yield, see Experimen-
tal Section). We have already observed the analogous
conversion of a disilanylplatinum (cis-(Me3SiClMeSi)-
Pt(SiMe2Cl)(PEt3)2) into a silylplatinum species (cis-
(ClMe2Si)2Pt(PEt3)2) in the presence of a silylene trap-
ping agent (benzil).24 The formation of 2b would be best
explained by R-migration of the Me3Si group of the
SiMe2SiMe3 ligand, giving a Pt(dSiMe2)(SiMe3) inter-
mediate and subsequent extrusion of SiMe2 species. A
similar mechanism was previously proposed in the
On the basis of the thermochemical considerations of
the reactions between platinum(0) species and group 14
metal halides R3EX (E ) Sn, Ge, Si; X ) Br, Cl), Eaborn
et al. previously proposed that the E-C bonds are more
easily cleaved than the E-X bonds.12a Indeed, R3SnX
(R ) Ph, X ) I, Br, Cl; R ) Me, X ) Br, Cl) were
reported to react with Pt(CH2dCH2)(PPh3)2 at the Sn-R
bonds to form cis-R2XSnPtR(PPh3)2 species.12 The
present study, however, demonstrates that halosilanes
(18) For examples of 31P NMR of trans-bis(phosphine)platinum
species, see: (a) Pregosin, P. S.; Kunz, R. W. 31P and 13C NMR of
Transition Metal Phosphine Complexes; Springer-Verlag: Berlin,
Germany, 1979. (b) Duncan, W.; Anderson, W.; Ebsworth, E. A. V.;
Rankin, D. W. H. J . Chem. Soc., Dalton Trans. 1973, 2370.
(19) For instance, see: (a) Reference 2, p 306. (b) Stille, J . K.; Lau,
K. S. Y. Acc. Chem. Res. 1977, 10, 434.
(20) Armitage, D. A. In Comprehensive Organometallic Chemistry;
Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon: Oxford,
U.K., 1982; Chapter 9, p 6.
(22) Glockling, F.; Hooton, K. A. J . Chem. Soc. A 1968, 826.
(23) (a) Stille, J . K.; Lau, K. S. Y. J . Am. Chem. Soc. 1976, 98, 5841.
(b) Eaborn, C.; Griffiths, R. W.; Pidcock, A. J . Organomet. Chem. 1982,
225, 331.
(24) Tanaka, Y.; Yamashita, H.; Tanaka, M. Organometallics 1995,
14, 530.
(21) Tolman, C. A. Chem. Rev. 1977, 77, 313.

Addition of Si-Halogen Bonds to Pt(0) Complexes
Organometallics, Vol. 16, No. 21, 1997 4699
photochemical conversion of Cp(CO)2FeSiMe2SiMe3 into
Cp(CO)2FeSiMe3.25
conversion of 2a (eq 4). Likewise, the reaction of 2a
Besides the silicon-halogen bonds, the reactivities of
the Si-S and Si-N bonds have been examined under
similar conditions. However, monitoring the reactions
of 1d with Me3Si-SPh, Me3Si-N(CH2)4 (N-(trimethyl-
silyl)pyrrolidine), and Me3Si-N3 by 1H and/or 31P NMR
did not reveal any recognizable Me3Si-Pt proton signals
up to 120 °C.
Rea ctivities of tr a n s-Ha logen o(silyl)bis(p h os-
p h in e)p la tin u m Sp ecies. There have been a few
limited investigations on the reactivities of trans-R3-
SiPtClL2 (R ) Me, Ph; L ) PEt3, PPhMe2) complexes
toward water,15a hydrogen,15a 1,2-dichloroethane,15a or-
ganoalkali and organoalkaline earth metals (aryllithi-
um, arylmagnesium bromide),26 metal salts (iodides,
thiocyanates, and azides of alkali metals),26 and some
unsaturated compounds (phenylacetylene, tetracyano-
ethylene, etc.).15a,26 However, the reactivities of the
silylplatinum species have not been fully clarified as yet.
In order to learn other aspects of the reactivities and/
or to find a clue for the development of new catalyses,
we have examined the reactivities of the silyl species
2a ,b toward phosphines, organometallics (organomer-
cury, organozinc, etc.), hydrosilanes, and olefinic com-
pounds.
with Ph2Hg (1 equiv) at 60 °C over 40 min produced
Me3SiPh in ∼90% yield with almost complete consump-
tion of 2a . Me3SiBr itself did not react with R2M (Et2-
Zn, Ph2Hg) under comparable conditions, indicating that
a pathway involving reductive elimination of Me3SiBr
and its interaction with R2M to give Me3SiR was not
likely. Accordingly, the formation of Me3SiR would be
best explained by the reaction sequence of transmeta-
lation between 2a and R2M, forming a Me3Si-Pt-R
intermediate,28 and subsequent reductive elimination
of Me3SiR.
(c) Rea ction s w ith Hyd r osila n es. Heating a mix-
ture of 2a and Me2PhSiH (2 equiv) in benzene-d6 at 60
°C for 10 min caused partial silyl group exchange to give
trans-Me2PhSiPtBr(PEt3)2 (2i) and Me3SiH (eq 5). The
(a ) Rea ction s w ith P h osp h in es. Treatment of 2a
with PEt3 (2 equiv) in benzene-d6 below 90 °C did not
cause any significant change in the NMR. However,
heating the mixture at 120 °C for 3 h formed Me3SiBr
(∼50% yield) and Pt(PEt3)3 with consumption of 2a
(∼60% conversion)27 (eq 3). Further heating for 2 h
reaction proceeded cleanly without formation of other
platinum species. The ratio of the remaining 2a /2i was
estimated to be ∼90/10 by 1H NMR. When the mixture
was heated to 90 °C, the ratio of 2a /2i changed to ∼15/
85 (10 min) and to ∼5/95 (30 min). Reductive elimina-
tion of Me3SiBr from 2a did not significantly take place
in the reaction (yield of Me3SiBr e 0.5%).
The iodide complex 2b reacted with Me2PhSiH more
readily to give trans-Me2PhSiPtI(PEt3)2 (2j) and Me3-
SiH; the ratios of 2b/2j were ∼10/90 (60 °C, 10 min) and
∼5/95 (30 min). These reactions were reversible, and
further heating did not substantially change the ratios
of 2a /2i and 2b/2j. The dihydrosilane MePhSiH2 ex-
hibited much higher reactivity than the monohydride
Me2PhSiH. Thus, 2b smoothly reacted with MePhSiH2
even at room temperature to provide trans-MePhHSiP-
tI(PEt3)2 (2k ) and Me3SiH with almost complete con-
sumption of 2b (4 h, 2b/2k ) ∼0/100). In the reaction
of 2b with Me2PhSiH or MePhSiH2, formation of Me3-
SiI was not observed by NMR. The reaction was
generally clean, and each silylplatinum product was
isolated in good yield (2i, 69%; 2j, 86%; 2k , 93%) by
evaporation of volatiles followed by recrystallization
from pentane, offering a convenient method to prepare
various halogeno(silyl)bis(phosphine)platinum com-
plexes.
The present silyl group exchange is likely to proceed
via oxidative addition of the Si-H bonds of the hydrosi-
lanes to 2a or 2b, forming hexacoordinate bis(silyl)-
platinum(IV) species (3), and subsequent reductive
elimination of Me3SiH, providing the silylplatinums 2i-
k . A similar addition-elimination process was previ-
ously proposed in the reactions of platinum(II) hydrides
with hydrosilanes, affording silylplatinum(II) species
hardly changed the product distribution. When PPh3
was used in place of PEt3, the reaction took place more
readily to give a higher yield of Me3SiBr (∼80%) with a
higher conversion of 2a (∼90%) (120 °C, 5 h). Unless
the extra phosphines were present, the reaction was
considerably slow to proceed; the yield of Me3SiBr was
only ∼10% with ∼25% conversion of 2a (120 °C, 5 h).
These results clearly indicate that oxidative addition of
the Si-Br bond to platinum(0) species is reversible and
reductive elimination of the Si-Br bond occurs in the
presence of extra phosphines. Higher conversion of 2a
in the presence of PPh3 is probably associated with a
lower rate of the reverse reaction; Pt(PEt3)p(PPh3)q
species, which are likely to be formed from 2a and PPh3,
seem to be less reactive for oxidative addition than Pt-
(PEt3)m, judging from the result that 1c,d exhibited
much higher reactivity toward halosilanes than 1a .
(b) Rea ction s w ith Or ga n om eta llics. Silylplati-
num species 2a was inert toward Ph4Sn (2 equiv) in
benzene-d6 even at 90 °C. In contrast, 2a smoothly
reacted with Et2Zn (1 equiv) at room temperature for
∼10 min to provide Me3SiEt in g90% yield with g95%
(25) (a) Pannell, K. H.; Cervantes, J .; Hernandez, C.; Cassias, J .;
Vincenti, S. P. Organometallics 1986, 5, 1056. (b) Tobita, H.; Ueno,
K.; Ogino, H. Chem. Lett. 1986, 1777.
(26) Chatt, J .; Eaborn, C.; Kapoor, P. N. J . Organomet. Chem. 1970,
23, 109.
(27) In the reactions of 2a with phosphines or styrene, some amounts
of (Me3Si)2O (10-35%) were also formed, although the origin of the
oxygen was ambiguous.
(28) For examples of transmetalation between halogenometal species
and organometallics, see ref 2, p 704.

4700 Organometallics, Vol. 16, No. 21, 1997
Yamashita et al.
along with hydrogen.29 In the foregoing reactions,
formation of the thermodynamically more stable R3Si-
Pt (R3 ) Me2Ph, MePhH) bond as compared with the
Me3Si-Pt bond would be a driving force. On the basis
of the ratios of 2b/2j and 2b/2k , the strength of R3Si-Pt
bonds is estimated to increase in the order of R3Si )
Me3Si < Me2PhSi < MePhHSi. This sequence is
consistent with the suggestion that electronegative
groups at silicon atoms stabilize the silicon-metal
bonds.30 On the other hand, no intermediate species
were observed in NMR monitoring of the reactions,
suggesting that oxidative addition of the Si-H bond was
the rate-determining step. The iodide ligand has weaker
electronegativity than the bromide ligand and would be
favorable for oxidative addition of the Si-H bond,
resulting in a higher rate of the exchange reaction.31 In
addition, the strong trans influence of the iodide ligand
compared with that of the bromide ligand would also
promote the reaction by facilitating the cleavage of the
Si-Pt bond.
dehydrogenative silylation of olefins with hydrosilanes.36
In addition, we have observed that a bis(silyl)platinum
species, cis-(Me2PhSi)2Pt(PMePh2)2, reacts with styrene
to yield a styrylsilane, presumably via similar elemental
steps (eq 7).35a These results could be successfully
applied to the development of novel catalyses, such as
in a palladium-catalyzed Heck-type reaction of Me3SiI
with olefins32 (eq 8) and a platinum-catalyzed reaction
of disilanes with olefins,37 both of which provided
alkenylsilanes.
Assuming that 3 is involved as an intermediate, it
seems possible to get a bis(silyl) species, (Me3Si)(R3Si)-
Pt(PEt3)2, by removal of the hydrogen halides HX from
the platinum(IV) species 3 using appropriate bases.
However, addition of Et3N (2 equiv) did not affect the
product distribution in the reaction of 2a with Me2-
PhSiH.
(d ) Rea ction s w ith Olefin ic Com p ou n d s. Silyl
species 2a did not react with isoprene in benzene-d6 up
to 60 °C. The reaction with styrene (2 equiv) did not
take place up to 90 °C either. However, when the
mixture of 2a and styrene was heated at an elevated
temperature (120 °C) for 4 h, PhCHdCHSiMe3 (∼5%,
E/ Z ≈ 8/1) was obtained along with Me3SiBr (∼50%)
and recovered 2a (∼10%)27 (eq 6). The reaction in the
In contrast with styrene, we have found that acetyl-
enes RCtCR (R ) Ph, Pr) smoothly insert into the Si-
Pt bonds of 2a ,b at 90-120 °C to give the corresponding
(â-silylvinyl)platinum species in high yields (g90%).38
High reactivities of acetylenes as compared with olefins
have been generally observed in reactions with other
silylplatinum complexes.39
NMR Sp ectr a of tr a n s-Ha logen o(silyl)bis(p h os-
p h in e)p la tin u m Sp ecies. 1H, 13C, 29Si, 31P, and 195Pt
NMR spectral data of the resulting platinum species
15a
2a -k and trans-Me3SiPtCl(PEt3)2 are summarized in
Tables 2-4. All the complexes show satisfactory NMR
spectra for the proposed structures.
1
The H and 13C NMR signals of the PEt3 and PMe3
ligands have virtual coupling with the trans phosphines,
as has been observed for other trans-bis(phosphine)-
platinum(II) complexes.40 Other characteristic features
of the chemical shifts and the coupling constants in the
series of trans-Me3SiPtX(PEt3)2, trans-Me3-nClnSiPtCl-
presence of Et3N (5 equiv) at 120 °C over 5.5 h also
provided PhCHdCHSiMe3 (∼2% yield, E/ Z ≈ 4/1) along
with a larger amount of Me3SiBr (∼75%) and unreacted
2a (e5%).32 The formation of the styrylsilane would be
best explained by styrene insertion into the Si-Pt bond
of 2a ,33 giving a (1-phenyl-2-silylethyl)platinum species
(4), followed by â-hydride elimination from the 2-silyl-
ethyl moiety of 4.34,35 A similar reaction sequence was
previously suggested for group 8 or 9 metal-catalyzed
(36) For instance, see: Kakiuchi, F.; Nogami, K.; Chatani, N.; Seki,
Y.; Murai, S. Organometallics 1993, 12, 4748 and references cited
therein.
(37) Hayashi, T.; Kawamoto, A. M.; Kobayashi, T.; Tanaka, M. J .
Chem. Soc., Chem. Commun. 1990, 563.
(38) (a) Yamashita, H.; Tanaka, M.; Goto, M. Organometallics 1993,
12, 988. See also ref 26. (b) Oxidative addition of the Si-I bond of an
iodosilane to a palladium complex and subsequent CtC bond insertion
into the resulting Si-Pd species were proposed as key elemental steps
in the palladium-catalyzed three-component coupling of an iodosilane
(R3SiI), an acetylene (R′CtCH), and an organometallic (R′′SnBu3, R′′2-
Zn), giving an alkenylsilane derivative (R3SiCHdCR′R′′). See: Chatani,
N.; Amishiro, N.; Murai, S. J . Am. Chem. Soc. 1991, 114, 7779.
Chatani, N.; Amishiro, N.; Takaya, M.; Yamashita, T.; Murai, S. J .
Org. Chem. 1995, 60, 1834.
(39) (a) Reference 26. (b) Reference 35a. (c) Tanaka, M.; Uchimaru,
Y.; Lautenschlager, H.-J . J . Organomet. Chem. 1992, 428, 1.
(40) For instance, see: (a) Duddell, D. A.; Evans, J . G.; Goggin, P.
L.; Goodfellow, R. J .; Rest, A. J .; Smith, J . G. J . Chem. Soc. A 1969,
2134. (b) Brown, M. P.; Puddephatt, R. J .; Upton, C. E. E. J . Chem.
Soc., Dalton Trans. 1974, 2457. (c) Rieger, A. L.; Carpenter, G. B.;
Rieger, P. H. Organometallics 1993, 12, 842 and references cited
therein.
(29) Bentham, J . E.; Cradock, S.; Ebsworth, E. A. V. J . Chem. Soc.
A 1971, 587.
(30) For instance, see ref 3b, pp 28, 84.
(31) We thank a reviewer for providing an instructive suggestion.
(32) Preliminary results were reported: Yamashita, H.; Kobayashi,
T.; Hayashi, T.; Tanaka, M. Chem. Lett. 1991, 761.
(33) For examples of olefin insertion into silicon-metal bonds, see
ref 3d.
(34) For examples of â-hydride elimination, see ref 2, p 386.
(35) For alkenylsilane formation in the reaction of silicon-metal
bonds with olefins, see: (a) Kobayashi, T.; Hayashi, T.; Yamashita,
H.; Tanaka, M. Chem. Lett. 1989, 467. (b) Thorn, D. L.; Harlow, R. L.
Inorg. Chem. 1990, 29, 2017.

Addition of Si-Halogen Bonds to Pt(0) Complexes
Ta ble 2. 1H NMR of 2a
δ(H3CSiPt) J PtH (Hz)
Organometallics, Vol. 16, No. 21, 1997 4701
δ(others)
3
complex
trans-Me3SiPtCl(PEt3)2
trans-Me3SiPtBr(PEt3)2 (2a )
trans-Me3SiPtI(PEt3)2 (2b)
0.51
0.45
0.45
0.90
1.17
0.47
0.40
0.14
0.51
0.64
0.62
0.82j
25.3
25.5
24.9
21.7
14.6
26.9
26.7
0.99,b 1.92c (3J PtH ) 22.2 Hz)
0.97,b 1.96c (3J PtH ) 22.5 Hz)
0.96,b 2.02c (3J PtH ) 23.1 Hz)
0.96,b 1.97c (3J PtH ) 21.4 Hz)
0.94,b 2.00c (3J PtH ) 21.0 Hz)
1.28f (3J PtH ) 30.5 Hz)
trans-Me2ClSiPtCl(PEt3)2 (2c)
trans-MeCl2SiPtCl(PEt3)2 (2d )
trans-Me3SiPtBr(PMe3)2 (2e)d,e
trans-Me3SiPtI(PMe3)2 (2f)d,g
trans-Me3SiPtI(PMe2Ph)2 (2g)d,h
trans-Me3SiMe2SiPtI(PEt3)2 (2h )
trans-Me2PhSiPtBr(PEt3)2 (2i)
trans-Me2PhSiPtI(PEt3)2 (2j)
trans-MePhHSiPtI(PEt3)2 (2k )
1.37f (3J PtH ) 31.1 Hz)
3
∼23
1.86i (br, J PtH ≈ 20 Hz, 12H, PCH3), 6.8-7.3 and 7.5-7.8 (each m, 10H, C6H5)
33.6
27.0
26.5
33.2
0.25 (s, 9H, H3CSiSi), 0.97,b 2.06c (3J PtH ) 20.3 Hz)
0.95,b 1.84c (3J PtH ) 21.7 Hz), 7.09-7.27 and 7.75-7.83 (each m, 5H, C6H5)
0.93,b 1.87c (3J PtH ) 22.2 Hz), 7.07-7.23 and 7.68-7.77 (each m, 5H, C6H5)
0.88,b 1.90-2.12 (m), 4.21(qt, J HH ) 4.0 Hz, J PH ) 14.0 Hz,
3
3
2J PtH ) 63.6 Hz, 1H, HSi), 7.11-7.28 and 7.79-7.87 (each m, 5H, C6H5)
a
b
3
3
3
2
d
In C6D6 at 20-25 °C. tt, J HH
≈
i
1/2| J PH
+
5J PH| ≈ 7.8 Hz, 18H, PCCH3. c qt, J HH ≈ | J PH
+
4J PH| ≈ 7.8 Hz, 12H, PCH2. Small
amounts of phosphorus-containing impurities were present. e In C6D5CD3 at -30 °C. f t, | J PH + 4J PH| ≈ 6.6 Hz, 18 H, PCH3. In C6D5CD3
2
g
h
2
j 3
at -20 °C. In C6D5CD3 at -60 °C. The | J PH
+
4J PH| value was not confirmed.
J
) 4.0 Hz.
HH
Ta ble 3. 13C NMR of 2a
2J PtC
3J PC
complex
δ(CSiPt)
(Hz)
(Hz)
δ(others)
b
2
trans-Me3SiPtCl(PEt3)2
8.1
8.1
8.1
12.8
18.1
7.3
7.0
6.3
6.4
78.4
77.8
75.0
112
3.2 8.7 (3J PtC ) 28.8 Hz, PCC), 16.8c (t, J PC ) 16.8 Hz, J PtC ) 42.0 Hz, PC)
b 2
trans-Me3SiPtBr(PEt3)2 (2a )
trans-Me3SiPtI(PEt3)2 (2b)
trans-Me2ClSiPtCl(PEt3)2 (2c)
trans-MeCl2SiPtCl(PEt3)2 (2d )
trans-Me3SiPtBr(PMe3)2 (2e)c,d
trans-Me3SiPtI(PMe3)2 (2f)c,e
trans-Me3SiPtI(PMe2Ph)2 (2g)c,f
trans-Me3SiMe2SiPtI(PEt3)2 (2h )
3.4 8.8 (3J PtC ) 28.3 Hz, PCC), 17.8 (t, J PC ) 16.9 Hz, J PtC ) 42.9 Hz, PC)
3.8 8.9 (3J PtC ) 27.9 Hz, PCC), 19.4 (t, J PC ) 17.0 Hz,
) 44.0 Hz, PC)
PtC
b
2J
8.7 (3J PtC ) 26.5 Hz, PCC), 16.3 (t, J PC ) 17.5 Hz, J PtC ) 36.6 Hz, PC)
b
2
∼2
8.5 (3J PtC ) 24.5 Hz, PCC), 16.1 (t, J PC ) 17.4 Hz, J PtC ) 33.9 Hz, PC)
b 2
b
2
154
∼1
78.1
73.9
∼65
42.0
3.8 16.6 (t, J PC ) 19.1 Hz, J PtC ) 47.4 Hz, PC)
b
2J
4.2 18.1 (t, J PC ) 19.3 Hz,
) 49.5 Hz, PC)
PtC
∼4
19.0 (t, J PC ) 19.3 Hz, PC)g
b
4.6 1.0 (3J PtC ) 12.1 Hz, CSiSiPt), 9.0 (3J PtC ) 29.5 Hz, PCC),
b 2
19.4 (t, J PC ) 17.2 Hz, J PtC ) 43.5 Hz, PC)
b
2
trans-Me2PhSiPtBr(PEt3)2 (2i)
trans-Me2PhSiPtI(PEt3)2 (2j)
trans-MePhHSiPtI(PEt3)2 (2k )
6.9
6.7
76.0
73.1
3.0 8.8 (3J PtC ) 27.6 Hz, PCC), 17.5 (t, J PC ) 17.1 Hz, J PtC ) 40.1 Hz, PC),
127.5 (m-C), 128.0 (p-C), 134.6 (3J PtC ) 21.8 Hz, o-C),
3
2
148.2 (t, J PC ) 3.3 Hz, J PtC ≈ 56 Hz, ipso-C)
3.1 9.0 (3J PtC ) 27.1 Hz, PCC), 19.2 (t, J PC ) 17.3 Hz, J PtC ) 41.3 Hz, PC),
b
2
127.6 (m-C), 128.0 (p-C), 134.4 (3J PtC ) 19.2 Hz, o-C),
3
2
147.8 (t, J PC ) 3.8 Hz, J PtC ≈ 56 Hz, ipso-C)
b
2
-0.4
58.0 ∼1
8.6 (3J PtC ) 27.3 Hz, PCC), 17.7 (t, J PC ) 17.9 Hz, J PtC ) 35.8 Hz, PC),
127.7 (m-C), 128.4 (p-C), 135.3 (3J PtC ) 27.2 Hz, o-C),
3
2
143.4 (t, J PC ) 1.8 Hz, J PtC ≈ 88 Hz, ipso-C)
a
b
1
d
In C6D6 at 20-25 °C. J PC
)
1/2| J PC
+
3J PC|. c Small amounts of phosphorus-containing impurities were present. In C6D5CD3 at
g
3
-30 °C. e In C6D5CD3 at -20 °C. f In C6D5CD3 at -60 °C. The J PtC value of the methyl carbon and the chemical shifts of the phenyl
carbons in the PMe2Ph ligand were not confirmed.
Ta ble 4. 29Si, 31P , a n d 195P t NMR of 2a
complex
δ(29Si)
δ(31P) δ(195Pt)
1J PtSi (Hz)
2J PSi (Hz)
1J PtP (Hz)
trans-Me3SiPtCl(PEt3)2
-15.6
-12.2
-8.0
23.0
21.0 -4985 1256
19.2 -5015 1248
16.3 -5039 1215
20.6 -4860 1614
20.1 -4779 2135
-11.9 -5001 1227
-14.2 -5040 1192
10.3
9.7
8.8
10.3
12.3
10.3
9.6
2859
2864
2869
2674
2516
2772
2781
2914
2820
2780
2796
2614
trans-Me3SiPtBr(PEt3)2 (2a )
trans-Me3SiPtI(PEt3)2 (2b)
trans-Me2ClSiPtCl(PEt3)2 (2c)
trans-MeCl2SiPtCl(PEt3)2 (2d )
trans-Me3SiPtBr(PMe3)2 (2e)b,c
trans-Me3SiPtI(PMe3)2 (2f)b,d
trans-Me3SiPtI(PMe2Ph)2 (2g)b,e
18.6
-11.4
-7.1
-8.2
-1.1 -5136 1130f
15.4 -5096 1198 (SiR), 119 (Siâ)
17.1 -5042 1336
9.3
trans-Me3SiMe2SiPtI(PEt3)2 (2h ) -20.8 (SiRPt), -17.9 (SiâSiPt)
trans-Me2PhSiPtBr(PEt3)2 (2i)
trans-Me2PhSiPtI(PEt3)2 (2j)
trans-MePhHSiPtI(PEt3)2 (2k )
9.2 (SiR), ∼0 (Siâ)
-12.6
-10.9
-22.7
10.0
14.2 -5065 1296
12.8 -5244 1318
9.1
11.0
a
b
d
In C6D6 at 20-25 °C. Small amounts of phosphorus-containing impurities were present. c In C6D5CD3 at -30 °C. In C6D5CD3 at
-20 °C. e In C6D5CD3 at -60 °C. f At 20 °C. The J PtSi value was not confirmed at -60 °C.
1
(PEt3)2, trans-R2MeSiPtI(PEt3)2, and trans-Me3SiPtIL2
are as follows.
(b) tr a n s-Me3-n Cln SiP tCl(P Et3)2. The 29Si NMR is
contrasted with that reported for some Me3-nClnSi-M
(M ) Fe, Ru, Os) species,43 the 29Si NMR chemical shifts
of which linearly increase in the order n ) 0 < 1 < 2.
(a ) tr a n s-Me3SiP tX(P Et3)2. The 29Si resonances
shift downfield with a decrease in the electronegativity
1
3
of the halogen atom, while the tendencies for the J PtSi
Meanwhile, the J PtH(MeSiPt) value follows the se-
2
and J PSi values are similar to those reported for trans-
quence n ) 0 > 1 > 2, which is similar to that reported
Ph3SiPtX(PMe2Ph)2 (X ) Cl, Br, I).41 The trend for 31P
for Me3-nClnE-Pt species (E ) Ge, Sn; n ) 0, 1).10,13 In
1
2
2
and 195Pt resonances and J PtP is also similar to that
contrast, the J PtC,
1J PtSi, and J PSi values adopt the
manifested in the trans-MePtXL2 (X ) Cl, Br, I; L )
(42) For instance, see: Kennedy, J . D.; McFarlane, W.; Puddephatt,
R. J .; Thompson, P. J . J . Chem. Soc., Dalton Trans. 1976, 874 and
references cited therein.
PMe2Ph, PEt3) species.42
(41) Latif, L. A. J . Chem. Res., Miniprint 1995, 1568.
(43) Krentz, R.; Pomeroy, R. K. Inorg. Chem. 1985, 24, 2976.

4702 Organometallics, Vol. 16, No. 21, 1997
Yamashita et al.
reverse order, n ) 0 e 1 < 2, which seems to be
reasonable, since an increase in the number of elec-
tronegative substituents at silicon atoms is likely to
shorten silicon-metal bonds30 to result in larger coupling
constants. The correlations regarding the 195Pt reso-
of the reactivities of other organosilanes and/or silyl-
metal complexes are subjects for further investigations.
Exp er im en ta l Section
1H, 13C, 29Si, 31P, and 195Pt NMR spectra were recorded on
Hitachi R-40, J EOL FX-90A, Bruker AC-200, and/or Bruker
1
nance and J PtP value are similar to those observed in
the trans-H3-nXnSiPtX(PEt3)2 (X ) Cl, Br) species.44
(c) tr a n s-R2MeSiP tI(P Et3)2. The 1H chemical shifts
of the MeSiPt moieties follow the sequence R2 ) Me2 <
Me(Me3Si) < MePh < PhH, which, with the exception
of Me(Me3Si) species, may reflect the electronegativity
of the R2 substituents. On the other hand, the relevant
coupling constants increase in the orders R2 ) Me2 <
1
ARX-300 instruments (90, 200, or 300 MHz for H; 50.3 or 75.5
MHz for 13C; 59.6 MHz for 29Si; 36.2 or 121.5 MHz for 31P;
64.5 MHz for 195Pt). An INEPT technique was used for 29Si
NMR measurements (τ ) 37 ms, ∆ ) 12 ms).47 The chemical
shifts referenced to are as follows: Me4Si (0 ppm), C6D5H (7.16
1
ppm), or C6D5CD2H (2.09 ppm) for H NMR; C6D6 (128.0 ppm)
or C6D5CD3 (20.44 ppm) for 13C NMR; H3PO4 (85% solution in
D2O, 0 ppm) for 31P NMR; Me4Si (0 ppm) for 29Si NMR; Na2-
PtCl6 (saturated solution in D2O, 0 ppm) for 195Pt NMR. IR
spectra were obtained using J asco A-302 and/or J asco FT/IR-
5000 spectrometers. GC-MS analyses were performed with
a Shimadzu QP-1000 GC-MS spectrometer (EI, 70 eV).
Benzene and benzene-d6 were dried with sodium or molec-
ular sieves 4A and were distilled under nitrogen. The plati-
3
MePh < PhH < Me(Me3Si) for J PtH, Me(Me3Si) < PhH
2
< MePh < Me2 for J PtC, Me(SiMe3) < Me2 < MePh <
1
PhH for J PtSi, and Me2 < MePh < Me(SiMe3) < PhH
2
for J PSi. Although the inconsistency between them has
3
not been rationalized yet, the trend for J PtH, 1J PtSi, and
2J PSi, except for those of the Me(SiMe3) species, seems
to be consistent with the favorable effect of the elec-
tronegative substituents on stabilizing the silicon-
48
49
num complexes Pt(PPh3)4 (1a ), Pt[Ph2P(CH2)2PPh2]2 (1b),
50a
50b
51
Pt(PEt3)4 (1c), Pt(PEt3)3 (1d ), Pt(PMe3)4 (1e), Pt(PMe2-
1
52
15a
metal bonds. Meanwhile, the J PtP value follows the
Ph)4 (1f), and trans-Me3SiPtCl(PEt3)2
were prepared ac-
cording to procedures in the literature. The halosilanes
Me3SiBr, Me3SiCl, Me2SiCl2, MeSiCl3, and MePh2SiCl were
purchased and were distilled before use. The iodosilanes Me3-
SiI53 and Me3SiSiMe2I54 were synthesized by the reported
methods. Hydrosilanes (Me2PhSiH, MePhSiH2) and olefins
(isoprene, styrene) were dried with molecular sieves 4A and
were distilled in vacuo or under nitrogen. Et2Zn (1 M hexane
solution), Ph2Hg, and Ph4Sn were used as purchased. All
manipulations for the reactions and the isolation procedures
were carried out under nitrogen unless otherwise noted.
The identification of the products, such as Me3SiH, Me3SiEt,
Me3SiPh, (Me3Si)2O, and PhCHdCHSiMe3,55 was made by
comparison with the authentic samples and/or by NMR and
MS spectra.
Rea ction s of P la tin u m (0) Com p lexes w ith Ha losi-
la n es. The general procedure for NMR monitoring was as
follows. To a benzene-d6 or benzene (0.20-0.60 mL) solution
of a platinum(0) complex (0.075-0.30 mmol) placed in a thick-
walled NMR tube (ca. 5 mm o.d.) was added a halosilane (∼3
equiv), and the tube was sealed under nitrogen or in vacuo.
The tube was then heated at the temperature specified in
Table 1. Occasionally the heating was discontinued and 1H
and/or 31P NMR spectra were measured to evaluate the
progress of the reaction.
order R2 ) PhH < MePh < Me(SiMe3) < Me2, suggest-
ing that the cis influence45 of the R2MeSi ligand
decreases in the reverse order.
The disilanylplatinum species 2h displays two 29Si
resonances at similar positions (-20.8 and -17.9 ppm).
1
2
However, the values of J PtSi and J PSi for the silicon
atom (SiR) bound to the platinum (1198 and 9.2 Hz,
respectively) are much larger than those for the silicon
atom (Siâ) remote from the platinum (119 and ∼0 Hz,
respectively).
1
(d ) tr a n s-Me3SiP tIL2. The Me3Si H and 13C NMR
and 195Pt NMR resonances tend to shift downfield by
increasing the basicity of L (PMe2Ph < PMe3 < PEt3).
1
The same order is observed for the value of J PtSi
,
suggesting that the order of the cis influence is PMe2-
Ph > PMe3 > PEt3; less basic cis ligands are likely to
1
weaken the Si-Pt bond. The tendency for J PtP is
similar to that observed for other bis(phosphine)plati-
num(II) complexes.46
Con clu sion
When oxidative addition of the silicon-halogen bonds to Pt(0)
complexes took place, new MeSi proton signals with 195Pt
satellites appeared in the region of 0-1 ppm. These chemical
shifts and the coupling constants of 3J PtH were similar to those
of the purified samples (Table 2). In 31P NMR the reactions
of 1c,d showed new signals with 195Pt satellites having
coupling constants similar to those of the isolated samples
(Table 4). However, the reaction mixtures of 1e,f showed only
broad singlets without detectable 195Pt satellites, probably due
to rapid phosphine exchange reactions. The NMR yields of
We have demonstrated that oxidative addition of
silicon-halogen bonds to platinum(0) complexes pro-
ceeds, depending on the nature of the silicon-halogen
bonds and the phosphine ligands, to provide various
trans-halogeno(silyl)bis(phosphine)platinum(II) com-
plexes. The silyplatinum species undergo cleavage of
the Si-Pt bonds in the reactions with phosphines, group
12 organometals, hydrosilanes, and an olefin. In addi-
1
tion, measurements of the H, 13C, 29Si, 31P, and 195Pt
NMR spectra of the resulting silylplatinum species have
revealed some relationships between ligated groups, and
chemical shifts and coupling constants.
Development of new catalyses that involve oxidative
addition of the silicon-halogen bonds and clarification
(47) For a review of 29Si NMR, see: Blinka, T. A.; West, R. Adv.
Organomet. Chem. 1984, 23, 193.
(48) Ugo, R.; Cariati, F.; Monica, G. L. Inorg. Synth. 1968, 11, 105.
(49) Booth, G.; Chatt, J . J . Chem. Soc. A 1969, 2131.
(50) (a) Yoshida, T.; Matsuda, T.; Otsuka, S. Inorg. Synth. 1979,
19, 110. (b) Yoshida, T.; Matsuda, T.; Otsuka, S. Inorg. Synth. 1979,
19, 107.
(44) Anderson, D. W. W.; Ebsworth, E. A. V.; Rankin, D. W. H. J .
Chem. Soc., Dalton Trans. 1973, 2370.
(51) Mann, B. E.; Musco, A. J . Chem. Soc., Dalton Trans. 1980, 776.
(52) Pearson, R. G.; Louw, W.; Rajaram, J . Inorg. Chim. Acta 1974,
9, 251.
(53) Sakurai, H.; Shirahata, A.; Sasaki, K.; Hosomi, A. Synthesis
1979, 740.
(54) Ishikawa, M.; Kumada, M.; Sakurai, H. J . Organomet. Chem.
1970, 23, 63.
(55) Seyferth, D.; Vaughan, L. G.; Suzuki, R. J . Organomet. Chem.
1964, 1, 437.
(45) For instance, see: (a) Arnold, D. P.; Bennett, M. A. Inorg. Chem.
1984, 23, 2117 and references cited therein. (b) Reference 2, p 253.
(46) For instance: (a) MacDougall, J . J .; Nelson, J . H.; Mathey, F.
Inorg. Chem. 1982, 21, 2145. In the series of bis(trialkylphosphine)-
platinum(II) species, replacement of the alkyl groups by phenyl groups
1
seems to enlarge the J PtP value. See also: (b) Reference 42. (c) Grim,
S. O.; Keiter, R. L.; McFarlane, W. Inorg. Chem. 1967, 6, 1133.

Addition of Si-Halogen Bonds to Pt(0) Complexes
Organometallics, Vol. 16, No. 21, 1997 4703
the silylplatinum species were estimated on the basis of the
proton integral ratios of the phosphines and/or the unreacted
halosilanes to the produced MeSi-Pt moieties.
indicating occurrence of rapid phosphine exchange between
2f and PMe3-containing impurities such as [PMe3(SiMe3)]+I-;
the integral ratio of the PMe protons of 2f:impurities was
estimated at g9:1. The broad NMR signals were well-resolved
in toluene-d8 at -20 °C. 2f: IR (Nujol) 1305 (m), 1282 (m),
1234 (m), 948 (s), 830 (s), 737 (m), 727 (m), 673 (m), 656 (m),
619 (m) cm-1. Anal. Calcd for C9H27IP2PtSi: C, 19.75; H, 4.97.
Found: C, 19.97; H, 4.57.
Each silylplatinum was isolated in a separate reaction as
described below. NMR spectral data on the purified samples
1
of H, 13C, 29Si, 31P, and 195Pt are shown in Tables 2-4.56
(a ) tr a n s-Me3SiP tBr (P Et3)2 (2a ). Me3SiBr (1.29 mmol)
was added to a benzene (0.50 mL) solution of 1d (0.517 mmol)
in a glass tube (8 mm o.d.), which was then sealed and heated
at 120 °C for 7 h. The reaction mixture was concentrated in
vacuo, and pentane (∼1 mL) was added to the residue.
Filtration of the pentane solution followed by cooling of the
filtrate to -80 °C gave a yellow solid of crude 2a . Recrystal-
lization from pentane (∼0.5 mL) gave pure 2a (0.303 mmol,
59% yield) in the form of pale yellow needles. 2a : mp 58-60
°C (under N2); IR (Nujol) 1236 (w), 1038 (s), 840 (s), 768 (m),
742 (m), 618 (w) cm-1. Anal. Calcd for C15H39BrP2PtSi: C,
30.82; H, 6.73. Found: C, 30.80; H, 6.80.
(b) tr a n s-Me3SiP tI(P Et3)2 (2b). A mixture of Me3SiI (5.32
mmol), 1d (2.13 mmol), and benzene (1.7 mL) was heated in a
closed Schlenk tube at 80 °C for 50 min. Through a purifica-
tion procedure similar to that for 2a , 2b (1.74 mmol, 82% yield)
was obtained in the form of pale yellow needles. 2b: mp 79-
80 °C (under N2); IR (Nujol) 1253 (w), 1234 (w), 1036 (m), 835
(s), 756 (m), 735 (m), 719 (m), 669 (w), 617 (m) cm-1. Anal.
Calcd for C15H39IP2PtSi: C, 28.53; H, 6.22. Found: C, 28.75;
H, 6.12.
(g) tr a n s-Me3SiP tI(P Me2P h )2 (2g). A mixture of Me3SiI
(0.583 mmol), 1f (0.168 mmol), and benzene (0.50 mL) was
heated in a sealed glass tube at 120 °C for 21 h. Concentration
of the mixture in vacuo gave relatively pure 2g (∼110 mg) as
1
a yellow solid. Its H and 31P NMR in toluene-d8 showed the
existence of mainly two PMe species, 2g (1H NMR δ ∼1.8 (br
s); 31P NMR δ -5.8 (br s)) and unreacted 1f (1H NMR δ 1.45
3
1
(br s, J PtH ≈ 20 Hz); 31P NMR δ -34.4 (s, J PtP ) 3808 Hz))
(2g:1f ≈ 9:1). Attempts to improve the purity of 2g by
recrystallization with benzene or column chromatography with
alumina or Florisil were unsuccessful. Although the ligated
PMe2Ph of the relatively pure 2g showed rather broad NMR
resonances without detectable 195Pt satellites at room temper-
ature, relatively well-resolved signals could be observed at -60
°C.
(h ) tr a n s-Me3SiMe2SiP tI(P Et3)2 (2h ). A mixture of Me3-
SiSiMe2I (1.80 mmol), 1d (1.02 mmol), and benzene (1.0 mL)
was heated in a sealed glass tube at 60 °C for 1 h. The mixture
was concentrated in vacuo, and pentane (∼5 mL) was added
to the residue. Filtration of the pentane solution followed by
cooling of the filtrate to -20 °C gave nearly pure 2h (0.063
mmol, 68% yield) in the form of yellow cubic crystals. Recrys-
tallization from pentane gave analytically pure 2h . 2h : mp
76-80 °C (under N2); IR (Nujol) 1252 (w), 1236 (m), 1036 (s),
860 (w), 836 (m), 790 (s), 764 (m), 718 (m), 684 (w), 646 (w),
620 (w) cm-1. Anal. Calcd for C17H45IP2PtSi2: C, 29.61; H,
6.58. Found: C, 29.78; H, 6.29.
A benzene-d6 solution of 2h was left in a sealed NMR tube
at room temperature for 2.5 years. 1H and 31P NMR of the
resulting solution showed consumption of 2h (g95% conver-
sion) and formation of 2b (g80% NMR yield). In 1H NMR,
several unknown SiMe signals were also observed at 0-0.4
ppm with their integral ratio to 2b being ∼2:3 (two major
resonances of almost equal intensity at 0.268 and 0.270 ppm
with a combined ratio to total unknown SiMe signals being
∼2:5). GC-MS of the reaction mixture showed a major peak,
the parent ion of which corresponded to (SiMe2)5O. GC-MS:
m/ z (relative intensity) 306 (0.8, M+), 291 (3), 232 (96), 217
(26), 173 (15), 159 (21), 158 (35), 157 (18), 144 (27), 143 (16),
73 (100), 59 (17), 45 (30).
(c) tr a n s-Me2ClSiP tCl(P Et3)2 (2c). A mixture of Me2SiCl2
(0.837 mmol), 1d (0.335 mmol), and benzene (0.40 mL) was
heated in a sealed glass tube at 120 °C for 2 h. Concentration
of the mixture in vacuo gave nearly pure 2c (∼0.3 mmol, g95%
purity, g95% yield) as a colorless viscous oil. 2c: IR (neat)
1456 (s), 1421 (m), 1379 (m), 1243 (s), 1035 (s), 835 (s), 801
(s), 768 (s), 723 (s), 679 (m), 652 (m), 443 (s), 429 (s) cm-1
.
Anal. Calcd for C14H36Cl2P2PtSi: C, 30.00; H, 6.47. Found:
C, 31.65; H, 6.82. A satisfactory elemental analysis of 2c
was not obtained because of its high susceptivity to mois-
ture.
(d ) tr a n s-MeCl2SiP tCl(P Et3)2 (2d ). A mixture of MeSiCl3
(0.770 mmol), 1d (0.308 mmol), and benzene (0.40 mL) was
heated in a sealed glass tube at 90 °C for 30 min. Concentra-
tion of the mixture in vacuo gave nearly pure 2d (∼0.3 mmol,
g95% purity, g95% yield) as a colorless waxy solid. 2d : IR
(neat) 1458 (s), 1421 (s), 1381 (s), 1247 (s), 1036 (s), 790 (s),
772 (s), 729 (s), 704 (s), 632 (s), 458 (m), 420 (m) cm-1. Anal.
Calcd for C13H33Cl3P2PtSi: C, 26.88; H, 5.73. Found: C, 27.08;
H, 5.61.
(e) tr a n s-Me3SiP tBr (P Me3)2 (2e). A mixture of Me3SiBr
(0.644 mmol), 1e (0.160 mmol), and benzene (0.40 mL) was
heated in a sealed glass tube at 120 °C for 20 h. Concentration
of the reaction mixture followed by extraction with benzene
(0.5 mL × 2) gave relatively pure 2e (∼50 mg) as a pale yellow
solid. Its 1H and 31P NMR spectra in benzene-d6 displayed
PMe signals arising from mainly two species, 2e (1H NMR δ
1.34 (br s); 31P NMR δ -12.2 (br s)) and unreacted 1e (1H NMR
Rea ction s of 2a w ith P Et3 or P P h 3. A mixture of 2a
(0.030 mmol), PEt3 (0.060 mmol), and benzene-d6 (0.20 mL)
was sealed in an NMR tube. No substantial change was shown
1
by H NMR after the mixture was heated to 90 °C for 30 min.
When the mixture was heated to 120 °C, 1H NMR showed new
signals of Me3SiBr (0.30 ppm) and (Me3Si)2O (0.11 ppm) with
concomitant consumption of 2a . The yields of Me3SiBr and
(Me3Si)2O and the conversion of 2a were respectively estimated
by NMR at ∼15, ∼5, and ∼20% after 40 min of heating, ∼50,
∼10, and ∼60% after 3 h, and ∼50, ∼10, and ∼60% after 5 h.
31P NMR spectra of the reaction mixture displayed the signal
3
1
δ 1.41 (br s, J PtH ≈ 20 Hz); 31P NMR δ 53.4 (s, J PtP ) 3835
Hz)) (2e:1e ≈ 5:2). The attempt to improve the purity of 2e
by recrystallization from pentane was not successful. Al-
though the phosphine ligand of the relatively pure 2e showed
rather broad NMR resonances without detectable 195Pt satel-
lites at room temperature, well-resolved signals could be
observed in toluene-d8 at -30 °C.
1
of 1d at ∼40 (br, J PtP ≈ 4070 Hz) ppm with the signals of
free PEt3 at -18 (br) ppm and unreacted 2a .
Similarly, in the reaction using 2a (0.030 mmol), PPh3 (0.060
mmol), and benzene-d6 (0.20 mL), the yields of Me3SiBr and
(Me3Si)2O and the conversion of 2a were respectively estimated
at ∼25, ∼10, and ∼35% after 40 min of heating, ∼70, ∼10,
and ∼80% after 3 h, and ∼80, ∼10, and ∼90% after 5 h. 31P
NMR indicated formation of 1d (small) and several unidenti-
fied (phosphine)platinum species (6.9 (1J PtP ≈ 2730 Hz), 12.4
(1J PtP ≈ 2770 Hz) ppm, etc.) along with free PPh3 at -2 (br)
ppm and unreacted 2a . In the reaction without extra phos-
phines, the yields of Me3SiBr and (Me3Si)2O and the conversion
of 2a were respectively estimated at ∼5, ∼10, and ∼15% after
(f) tr a n s-Me3SiP tI(P Me3)2 (2f). A mixture of Me3SiI
(0.527 mmol), 1e (0.151 mmol), and benzene (0.30 mL) was
heated in a closed Schlenk tube at 80 °C for 1 h. Through a
purification procedure similar to that for 2a (recrystallization
from benzene-pentane), reasonably pure 2f (∼40 mg) was
obtained as a yellow solid. Although its elemental analysis
was almost satisfactory, the NMR signals for the phosphine
ligand were rather broad singlets at room temperature,
(56) The reported chemical shifts8 for 2 slightly deviated.

4704 Organometallics, Vol. 16, No. 21, 1997
Yamashita et al.
40 min, ∼10, ∼15, and ∼25% after 3 h, and ∼10, ∼15, and
∼25% after 5 h.
NMR spectral data of 2i-k are shown in Tables 2-4.
Physical, IR, and analytical data of 2i-k are as follows.
Rea ction s of 2a w ith Et2Zn or P h 2Hg. A hexane solution
of Et2Zn (∼1.0 M, 0.050 mL) was added to a benzene-d6 (∼0.15
mL) solution of 2a (0.050 mmol) placed in an NMR tube. 1H
and 31P NMR and GC-MS after ∼10 min at room temperature
showed g95% conversion of 2a and formation of Me3SiEt (1H
NMR δ -0.08 (s, SiCH3) ppm, g90% yield) along with several
unidentified (phosphine)platinum species (mainly three, A1:
2i: mp 80-82 °C (under N2); IR (Nujol) 1249 (m), 1102 (m),
1036 (m), 828 (m), 803 (s), 766 (s), 735 (s), 642 (m), 484 (m)
cm-1
. Anal. Calcd for C20H41BrP2PtSi: C, 37.15; H, 6.39.
Found: C, 36.56; H, 6.31.
2j: mp 77-78 °C (under N2); IR (Nujol) 1259 (m), 1245 (m),
1098 (m), 1035 (s), 835 (m), 799 (s), 770 (s), 735 (s), 712 (m)
cm-1
. Anal. Calcd for C20H41IP2PtSi: C, 34.64; H, 5.96.
1
A2:A3 ) ∼2:∼2:1). 31P NMR: A1, δ 12.7 (s, J PtP ) 2979 Hz);
Found: C, 34.69; H, 5.87.
A2, δ 18.1 (s, 1J PtP ) 2878 Hz); A3, δ 28.3 (s, 1J PtP ) 3247 Hz).
Similarly, in the reaction of 2a (0.050 mmol) with Ph2Hg
2k : mp 105-107 °C (under N2); IR (Nujol) 2076 (s, SiH),
1311 (m), 1243 (m), 1100 (m), 1031 (s), 1004 (m), 886 (s), 866
(s), 764 (s), 745 (m), 717 (s), 683 (m), 632 (m), 468 (m), 418
(m) cm-1. Anal. Calcd for C19H39IP2PtSi: C, 33.58; H, 5.78.
Found: C, 33.93; H, 5.64.
1
(0.050 mmol) in benzene-d6 (0.2 mL) at 60 °C for 40 min, H
and 31P NMR and GC-MS showed almost complete consump-
tion of 2a and formation of Me3SiPh (0.18 (s, SiCH3) ppm,
∼90% yield) along with several unidentified (phosphine)-
platinum species (mainly four, B1:B2:B3:B4 ) 6:8:7:4). 31P
NMR: B1, δ 3.0 (s, 1J PtP ) 4146 Hz); B2, δ 6.7 (s, 1J PtP ) 2395
Hz); B3, δ 11.3 (s, 1J PtP ) 2778 Hz); B4, δ 20.9 (s, 1J PtP ) 2690
Hz).
Rea ction of 2a w ith Styr en e. A mixture of 2a (0.05
mmol), styrene (0.10 mmol), and benzene-d6 (0.20 mL) was
sealed in an NMR tube. 1H NMR after the mixture was heated
to 90 °C for 15 min showed almost no change. When the
mixture was further heated at 120 °C, new proton signals of
Me3SiBr (0.30 ppm) and (Me3Si)2O (0.11 ppm) emerged with
consumption of 2a . The yields of Me3SiBr and (Me3Si)2O and
Rea ction s of 2a ,b w ith Me2P h SiH or MeP h SiH2.
A
mixture of 2a (0.030 mmol), Me2PhSiH (0.060 mmol), and
benzene-d6 (0.20 mL) was heated in a sealed NMR tube at 60
°C for 10 min. 1H NMR showed formation of the new SiMe
1
the conversion of 2a were respectively estimated by H NMR
at ∼30, ∼30, and ∼65% after 1 h of heating and ∼50, ∼35,
and ∼90% after 4 h. 31P NMR spectra of the resulting mixture
displayed new signals at 18.2 (1J PtP ≈ 3550 Hz) and 21.8 (1J PtP
≈ 2710 Hz) ppm (about 1:1 ratio), which were similar to those
3
species trans-(Me2PhSi)PtBr(PEt3)2 (2i; 0.60 (s, J PtH ) 27.0
3
Hz) ppm, ∼10% yield) and Me3SiH (-0.02 (d, J HH ) 3.6 Hz)
ppm) with concomitant consumption of 2a (∼10% conversion
of 2a ). The resulting mixture was further heated at the
elevated temperature of 90 °C. The yields of 2i (approximately
57
of Pt(PhCHdCH2)(PEt3)2 and trans-PtHBr(PEt3)2,58 respec-
tively. GC and GC-MS analysis of the reaction mixture
showed formation of PhCHdCHSiMe3 (∼5%, E/ Z ≈ 8/1) and
a small amount of its isomer (A, e0.3%). GC-MS: A, m/ z
(relative intensity) 176 (38, M+), 161 (68), 135 (65), 73 (100).59
1
equal to the conversions of 2a ) were estimated by H NMR at
∼85% after 10 min of heating and ∼95% after 30 min. 31P
NMR spectra of the reaction mixture displayed a new signal
for 2i at 17.1 (1J PtP ) 2781 Hz) ppm. In a separate reaction of
2a (0.045 mmol) with Me2PhSiH (0.090 mmol) in benzene-d6
(0.30 mL) at 90 °C for 1 h, the reaction mixture was
concentrated in vacuo. Recrystallization from pentane gave
2i (0.0309 mmol, 69% yield) as a white solid.
Similarly, when a mixture of 2a (0.050 mmol), styrene
(0.25 mmol), Et3N (0.25 mmol), and benzene-d6 (0.20 mL)
was heated to 120 °C for 5.5 h, NMR, GC, and GC-MS
analyses showed g95% conversion of 2a with formation of
PhCH)CHSiMe3 (∼2%, E/ Z ≈ 4/1), A (e0.2%), Me3SiBr
(∼75%), and (Me3Si)2O (∼15%).
Similarly, when a mixture of 2b (0.030 mmol), Me2PhSiH
(0.060 mmol), and benzene-d6 (0.20 mL) was left for 1 h at
room temperature, 1H and 31P NMR showed formation of trans-
1
(Me2PhSi)PtI(PEt3)2 (2j, ∼5% yield; H NMR δ 0.60 (3J PtH
)
Ack n ow led gm en t. We are grateful to Drs. Toshi-
aki Kobayashi and Teruyuki Hayashi for helpful sug-
gestions and discussions during this study. In addition,
we thank Professor Keith H. Pannell for his preliminary
29Si NMR measurement of 2h . Financial support from
the J apan Science and Technology Corporation (J ST)
through the CREST (Core Research for Evolutional
Science and Technology) program is also gratefully
acknowledged.
26.4 Hz, SiCH3); 31P NMR δ 14.2 (1J PtP ) 2797 Hz)) and Me3-
SiH with ∼5% conversion of 2b. The resulting mixture was
heated at 60 °C. The yields of 2j (approximately equal to the
conversions of 2b) were estimated at ∼90% after 10 min and
∼95% after 30 min. Concentration of the reaction mixture
followed by recrystallization from pentane gave 2j (0.026
mmol, 86% yield) as a pale yellow solid.
In the reaction of 2b (0.030 mmol) with MePhSiH2 (0.060
1
mmol) in benzene-d6 (0.20 mL) at room temperature, H and
OM970214Y
31P NMR showed formation of trans-(MePhHSi)PtI(PEt3)2 (2k ;
1H NMR δ 0.80 (d, 3J HH ) 4.0 Hz, 3J PtH ) 33.2 Hz, SiCH3); 31
P
NMR δ 12.8 (1J PtP ) 2615 Hz)) and Me3SiH. The yields of 2k
(approximately equal to the conversions of 2b) after standing
for 30 min, 1 h, and 4 h were estimated at ∼55, ∼90, and
∼100%, respectively. By recrystallization from pentane, 2k
(0.028 mmol, 93% yield) was isolated as a white solid.
(57) Cowan, R. L.; Troger, W. C. J . Am. Chem. Soc. 1989, 111, 4750.
(58) Socrates, G. J . Inorg. Nucl. Chem. 1969, 31, 1667.
(59) The m/ z values of the main fragment peaks are almost
consistent with those reported for Ph(Me3Si)CdCH2,60 although the
relative intensities among them do not coincide very well.
(60) Ando, W.; Sekiguchi, A. J . Organomet. Chem. 1977, 133, 219.