Mechanistic study on the insertion of phenylacetylene into cis-bis(silyl)platinum(II) complexes

Article abstract of DOI:10.1021/om980610w

Four bis(silyl)platinum complexes cis-Pt(SiR₃)₂(PMe₂Ph)₂ (SiR₃ = SiMe₂Ph (1a), SiMePh₂ (1b), SiPh₃ (1c), SiFPh₂ (1d)) have been prepared and their reactions with alkynes and alkenes examined. The X-ray structures of 1a-c exhibit significant distortion from the square planar geometry in the order 1b > 1c > 1a. Complexes 1a-d react with phenylacetylene in solution to give the corresponding insertion complexes cis-Pt{C(Ph)=CH(SiR₃)}(SiR₃)(PMe₂Ph) ₂ (2a-d). Complex le reacts also with acetylene to afford the insertion complex cis-Pt(CH=CHSiPh₃)(SiPh₃)(PMe₂Ph)₂ (2e), whose structure has been determined by X-ray diffraction study. Kinetic studies indicate the insertion process involving prior dissociation of PMe₂Ph ligand from 1, followed by insertion of phenylacetylene into the Pt-SiR₃ bond. The reactivity toward insertion decreases in the order 1c > 1a > 1b ?1d. Factors responsible for the reactivity order are discussed on the basis of kinetic data and X-ray structures.

Full text of DOI:10.1021/om980610w

5630
Organometallics 1998, 17, 5630-5639
Mech a n istic Stu d y on th e In ser tion of P h en yla cetylen e
in to cis-Bis(silyl)p la tin u m (II) Com p lexes
Fumiyuki Ozawa* and J un Kamite
Department of Applied Chemistry, Faculty of Engineering, Osaka City University,
Sumiyoshi-ku, Osaka 558-8585, J apan
Received J uly 20, 1998
Four bis(silyl)platinum complexes cis-Pt(SiR3)2(PMe2Ph)2 (SiR3 ) SiMe2Ph (1a ), SiMePh2
(1b), SiPh3 (1c), SiFPh2 (1d )) have been prepared and their reactions with alkynes and
alkenes examined. The X-ray structures of 1a -c exhibit significant distortion from the square
planar geometry in the order 1b > 1c > 1a . Complexes 1a -d react with phenylacetylene in
solution to give the corresponding insertion complexes cis-Pt{C(Ph)dCH(SiR3)}(SiR3)(PMe2-
Ph)2 (2a -d ). Complex 1c reacts also with acetylene to afford the insertion complex cis-Pt-
(CHdCHSiPh3)(SiPh3)(PMe2Ph)2 (2e), whose structure has been determined by X-ray
diffraction study. Kinetic studies indicate the insertion process involving prior dissociation
of PMe2Ph ligand from 1, followed by insertion of phenylacetylene into the Pt-SiR3 bond.
The reactivity toward insertion decreases in the order 1c > 1a > 1b . 1d . Factors responsible
for the reactivity order are discussed on the basis of kinetic data and X-ray structures.
In tr od u ction
In this study we examined structures and insertion
reactions with alkynes and alkenes of a series of bis-
(silyl)platinum complexes, cis-Pt(SiR3)2(PMe2Ph)2 (SiR3
) SiMe2Ph (1a ), SiMePh2 (1b), SiPh3 (1c), SiFPh2 (1d )).
Tanaka and co-workers previously reported that cis-Pt-
(SiMe2Ph)2(PMePh2)2 reacts with a variety of alkynes
and alkenes to give bis-silylation products,4 where no
insertion complexes were detected. On the other hand,
the present bis(silyl) complexes coordinated with PMe2-
Ph ligands have been found to provide the insertion
complexes of phenylacetylene cis-Pt{C(Ph)dCH-
(SiR3)}(SiR3)(PMe2Ph)2, which can be isolated. Thus we
could carry out detailed investigations into the insertion
mechanism using kinetic techniques and X-ray struc-
tural analyses. We herein show an interesting relation
between the reactivities and the structures of bis(silyl)
complexes that hitherto has not been observed.
Bis-silylation of unsaturated hydrocarbons catalyzed
by group 10 metals is a useful means of synthesizing
organosilicon compounds, in which two Si-C bonds are
created in one reaction.1 This reaction is generally
assumed to proceed via sequence of the following
elementary processes.2 The first step is oxidative addi-
tion of disilane to a low-valent metal species to give a
bis(silyl) complex.3 Insertion of a carbon-carbon mul-
tiple bond into the resulting metal-silicon bond pro-
vides an organo(silyl)metal intermediate,4-6 which re-
ductively eliminates bis-silylation product.7,8 Although
these elementary processes have been documented with
isolated silyl complexes,2-8 the factors governing the
reactivity, particularly for the insertion and reductive
elimination processes, have remained to be explored.9
(1) For recent examples see: Tsuji, Y.; Funato, M.; Ozawa, M.;
Ogiyama, H.; Kajita, S.; Kawamura, T. J . Org. Chem. 1996, 61, 5779.
Obara, Y. Tsuji, Y. Kawamura, T. Organometallics 1993, 12, 2853; J .
Am. Chem. Soc. 1993, 115, 10414; J . Am. Chem. Soc. 1995, 117, 9814.
Murakami, M.; Oike, H.; Sugawara, M.; Suginome, M.; Ito, Y.
Tetrahedron 1993, 49, 3933. Murakami, M.; Suginome, M.; Fujimoto,
K.; Nakamura, H.; Andersson, P. G.; Ito, Y. J . Am. Chem. Soc. 1993,
115, 6487. Finckh, W.; Tang, B.; Lough, A.; Manners, I. Organome-
tallics 1992, 11, 2904. Tsuji, Y.; Lago, R. M.; Tomohiro, S.; Tsuneishi,
H. Organometallics 1992, 11, 2353. Yamashita, H.; Catellani, M.;
Tanaka, M. Chem. Lett. 1991, 241. Ito, Y.; Suginome, M.; Murakami,
M. J . Org. Chem. 1991, 56, 1948. Murakami, M.; Andersson, P. G.;
Suginome, M.; Ito, Y. J . Am. Chem. Soc. 1991, 113, 3987. Kusumoto,
T.; Hiyama, T. Bull. Chem. Soc. J pn. 1990, 63, 3103. Hayashi, T.;
Kobayashi, T.; Kawamoto, A. M.; Yamashita, H.; Tanaka, M. Orga-
nometallics 1990, 9, 280. Hayashi, T.; Kawamoto, A. M.; Kobayashi,
T.; Tanaka, M. J . Chem. Soc., Chem. Commun. 1990, 563. For further
references see: Ozawa, F.; Sugawara, M.; Hayashi, T. Organometallics
1994, 13, 3237.
(5) Chatt, J .; Eaborn, C.; Kapoor, P. N. J . Organomet. Chem. 1970,
23, 109. Kiso, Y.; Tamao, K.; Kumada, M. J . Organomet. Chem. 1974,
76, 105. Eaborn, C.; Metham, T. N.; Pidcock, A. J . Organomet. Chem.
1977, 131, 377. Seyferth, D.; Goldman, E. W.; Escudie´, J . J . Organomet.
Chem. 1984, 271, 337. Tanaka, M.; Uchimaru, Y.; Lautenschlager, H.
J . Organometallics 1991, 10, 16. Pan, Y.; Mague, J . T.; Fink, M. J .
Organometallics 1992, 11, 3495. Yamashita, H.; Tanaka, M.; Goto, M.
Organometallics 1993, 12, 988.
(6) Ozawa, F.; Hikida, T. Organometallics 1996, 15, 4501.
(7) Tanaka, Y.; Yamashita, H.; Shimada, S.; Tanaka, M. Organo-
metallics 1997, 16, 3246.
(8) Ozawa, F.; Hikida, T.; Hayashi, T. J . Am. Chem. Soc. 1994, 116,
2844. Ozawa, F.; Hikida, T.; Hasebe, K.; Mori, T. Organometallics 1998,
17, 1018.
(9) For theoretical studies see: (a) Sakaki, S.; Mizoe, N.; Sugimoto,
M. Organometallics 1998, 17, 2510. (b) Sakaki, S.; Ogawa, M.; Musashi,
Y. J . Organomet. Chem. 1997, 535, 25. (c) Sakaki, S.; Mizoe, N.; Sumi,
N.; Biswas, B.; Sugimoto, M. Abstracts of 44th Symposium on Orga-
nometallic Chemistry, J apan; Kinki Chemical Society: Osaka, J apan,
1997; PA 105. (d) Sakaki, S.; Ogawa, M.; Kinoshita, M. J . Phys. Chem.
1995, 99, 9933. (e) Sakaki, S.; Ogawa, M.; Musashi, Y.; Arai, T. J . Am.
Chem. Soc. 1994, 116, 7258. (f) Hada, M.; Tanaka, Y.; Ito, M.;
Murakami, M.; Amii, H.; Ito, Y.; Nakatsuji, H. J . Am. Chem. Soc. 1994,
116, 8754.
(2) Brunstein, P.; Knorr, M. J . Organomet. Chem. 1995, 500, 21.
Recatto, C. A. Aldrichimica Acta 1995, 28, 85.
(3) Yamashita, H.; Kobayashi, T.; Hayashi, T.; Tanaka, M. Chem.
Lett. 1990, 1447. Murakami, M.; Yoshida, T.; Ito, Y. Organometallics
1994, 13, 2900. Suginome, M.; Oike, H.; Park, S.-S.; Ito, Y. Bull. Chem.
Soc. J pn. 1996, 69, 289. Suginome, M.; Oike, H.; Shuff, P. H.; Ito, Y.
Organometallics 1996, 15, 2170.
(4) Kobayashi, T.; Hayashi, T.; Yamashita, H.; Tanaka, M. Chem.
Lett. 1989, 467.
10.1021/om980610w CCC: $15.00 © 1998 American Chemical Society
Publication on Web 11/20/1998

Phenylacetylene Insertion into (SiR3)2-Pt Complexes
Organometallics, Vol. 17, No. 26, 1998 5631
F igu r e 2. Molecular structure of cis-Pt(SiPh3)2(PMe2Ph)2
(1c). Thermal ellipsoids are drawn at the 30% probability
level.
F igu r e 1. Molecular structure of cis-Pt(SiMe2Ph)2(PMe2-
Ph)2 (1a ). Thermal ellipsoids are drawn at the 30% prob-
ability level.
Ta ble 1. Selected Bon d Dista n ces a n d An gles a n d
31P {1H} NMR Da ta for 1a -c
Resu lts
complex
SiR3
1a
SiMe2Ph
122
1ba
SiMePh2
136
1c
SiPh3
145
1eb
SiH3
87
P r ep a r a tion a n d X-r a y Str u ctu r es of cis-Bis-
(silyl)p la tin u m (II) Com p lexes. Complexes 1a and 1b
were synthesized by the reactions of cis-PtCl2(PMe2Ph)2
with (organosilyl)lithium (2.2 equiv) in tetrahydrofuran
(THF).10 Since the yield of 1c prepared by the same
method was rather low (13%), this complex was syn-
thesized in 93% yield by the following route. Treatment
θc (deg)
Distances (Å)
2.359(2)
Pt-Si
Pt-P
2.370(1)
2.3701(9)
3.233(1)
2.374(3)
2.373(3)
2.396(2)
2.408(3)
3.334(4)
2.371
2.464
3.111
2.352(2)
Si‚‚‚Si
3.304(4)
10
of trans-PtCl(SiPh3)(PMe2Ph)2 with LiSiPh3 in THF
Angles (deg)
88.91(9)
at -50 °C provided trans-Pt(SiPh3)2(PMe2Ph)2 (31P{1H}
Si-Pt-Si
P-Pt-P
Si-Pt-P
86.02(5)
93.63(5)
163.52(4)
89.22(9)
93.49(9)
159.5(1)
159.7(1)
28.34
82.0
97.0
172.0
1
NMR: δ -11.7, J Pt-P ) 2700 Hz), which quickly
96.48(10)
152.42(7)
isomerized to 1c at room temperature. Complex 1d was
6
prepared by the reaction of cis-PtMe(SiPh3)(PMe2Ph)2
DAd
22.80
38.1
0.0
with HSiFPh2 (10 equiv) in benzene. All complexes thus
prepared were characterized by NMR spectroscopy and
elemental analysis. Complexes 1a and 1c were identi-
fied also by X-ray diffraction studies (Figures 1 and 2).
The structural parameters and 31P{1H} NMR data for
1a -c are summarized in Table 1. The data for 1b are
quoted from a recent report by Tsuji and co-workers.11a
Also included in this table are structural parameters
for cis-Pt(SiH3)2(PH3)2 (1e), which were estimated by
Sakaki and co-workers using ab initio MO calculation.9d
Tolman’s cone angles (θ)12 are given for indexes of
bulkiness of silyl ligands.13
31P{1H} NMR Datae
-7.6
δ
-6.6
-10.2
1J Pt-P (Hz) 1528 (1542) 1560 (1572) 1508 (1536)
Tc (°C) f
-35
-10
0
a
b
The data taken from ref 11a. Theoretical values for cis-
Pt(SiH3)2(PH3)2 taken from ref 9d. c Tolman’s cone angles for the
d
corresponding phosphine ligands (see text). Dihedral angles
between PtP2 and PtSi2 planes. e The data at 23 °C. J Pt-P
1
constants in parentheses are the values measured at -70 °C.
f Coalescence temperature for the satellite signals due to P-Si-
(transoid) and P-Si(cisoid) couplings (see text).
variation observed for 1a -c may be attributed primarily
to the difference in bulkiness of silyl ligands. Actually,
the Si-Pt-Si angles and the distances between the two
silicon atoms (Si‚‚‚Si) are significantly larger than those
of 1e and increase with increasing bulkiness of silyl
ligands (1a < 1b < 1c). On the other hand, dihedral
angles between the PtP2 and the PtSi2 plane exhibit
irregularity in their order (1a < 1c < 1b), not simply
accounted for by steric congestion around platinum.
Thus 1b with SiMePh2 ligands in the middle size has
the most twisted structure, while 1c with the biggest
As already documented for 1b,11a bis(triorganosilyl)-
platinum complexes including 1a and 1c have twisted
square planar geometry around platinum distinctly
distorted from planarity.14 Since 1e bearing compact
SiH3 and PH3 ligands has no distortion, the structural
(10) Chatt, J .; Eaborn, C.; Ibekwe, S. D.; Kapoor, P. N. J . Chem.
Soc. A 1970, 1343.
(11) (a) Tsuji, Y.; Nishiyama, K.; Hori, S.; Ebihara, M.; Kawamura,
T. Organometallics 1998, 17, 507. (b) Obora, Y.; Tsuji, Y.; Nishiyama,
Y.; Ebihara, M.; Kawamura, T. J . Am. Chem. Soc. 1996, 118, 10922.
(12) Tolman, C. A. Chem. Rev. 1977, 77, 313.
(13) Covalent radii of silicon and phosphorus are almost identical
with each other.
(14) Similar distortion from square planar geometry has been
observed for X-ray structures of bis(germyl)15 and bis(stannyl)11
complexes.
(15) Yamashita, H.; Kobayashi, T.-a.; Tanaka, M. Organometallics
1992, 11, 2330. Hatanaka, W.; Wada, T.; Mochida, K.; Yamamoto, A.
Abstracts of 45th Symposium on Organometallic Chemistry, J apan;
Kinki Chemical Society: Tokyo, J apan, 1998; PA 137.

5632 Organometallics, Vol. 17, No. 26, 1998
Ozawa and Kamite
SiPh3 ligands shows the medium dihedral angle. It is
further noted that 1b with the most twisted structure
has the shortest Pt-Si and Pt-P bonds. Since bond
lengths between metal center and coordinated atoms in
square planar complexes are known to vary with trans
influence,16 the significant distortion in 1b, which
reduces the direct labilizing interaction between mutu-
ally trans ligands, may be responsible for the shortest
bonds.
Tsuji and co-workers have recently demonstrated that
bis(silyl)- and bis(stannyl)platinum complexes including
1b undergo a rapid twist-rotation via a pseudo tetra-
hedral transition state in solution, which may be
confirmed by coalescence phenomena between satellite
signals due to P-E(transoid) and P-E(cisoid) couplings
(E ) Si, Sn) in 31P{1H} NMR spectra.11 In this study
we observed similar fluxional behavior for 1a and 1c.
As judging from the coalescence temperatures (Tc) listed
in Table 1, the ease of twist-rotation decreases in the
other 1a > 1b > 1c, probably reflecting increasing
electron-withdrawing character of silyl ligands in this
order.11b
F igu r e 3. Molecular structure of cis-Pt(CHdCHSiPh3)-
(SiPh3)(PMe2Ph)2 (2e). Thermal ellipsoids are drawn at the
30% probability level. Selected bond distances (Å) and
angles (deg): Pt-C1 ) 2.043(6), C1-C2 ) 1.338(8), C2-
Si1 ) 1.844(7), Pt-Si2 ) 2.389(2), Pt-P1 ) 2.330(2), Pt-
P2 ) 2.366(2), Pt-C1-C2 ) 139.7(5), C1-C2-Si1 )
132.9(5), C1-Pt-Si2 ) 83.5(2), C1-Pt-P2 ) 88.6(2), P1-
Pt-Si2 ) 92.52(5), P1-Pt-P2 ) 93.96(6), C1-Pt-P1 )
169.4(2), P2-Pt-Si2 ) 169.49(6).
Despite the occurrence of a rapid twist-rotation in
solution, however, the 1J Pt-P values observed in 31P{1H}
NMR spectra are nicely correlated with the Pt-P bond
lengths determined by X-ray structural analysis (Table
1
1). Thus the J Pt-P constants increase as the Pt-P
distances in the crystals decrease (1c > 1a > 1b).
Especially, complex 1b, which has distinctly shorter
Pt-P bonds than the others, exhibits a significantly
1
larger J Pt-P value at ambient (23 °C) as well as at low
appeared at δ 7.66 (dd) with large and small couplings
to trans and cis phosphorus nuclei (4J P-H ) 19.5 and
3.9 Hz); the coupling constants are consistent with the
Z arrangement around the CdC double bond. The R-
and â-olefinic carbons were observed at δ 182.9 (dd,
2J P-C ) 100 and 16 Hz) and 125.8 (s), respectively. The
absence of hydrogen at the R-carbon and the presence
at the â-carbon were confirmed by 13C NMR spectros-
copy in a DEPT mode. Complexes 2b-d showed com-
parable NMR data (see Experimental Section).
Several alkynes and alkenes were also employed for
the reactions with 1c, which possesses the highest
reactivity (vide infra). Dimethyl acetylenedicarboxylate
was inactive toward insertion at room temperature and
led to rapid decomposition of 1c, giving Ph3SiSiPh3.
Diphenylacetylene, 3-hexyne, tert-butylacetylene, and
styrene were also unreactive with 1c. On the other
hand, ethylene, acetylene, and 1-hexyne exhibited in-
sertion reactivity. The reaction with an excess amount
of ethylene proceeded at room temperature to give CH2d
CHSiPh3 in 93% yield (GLC). The reaction with acety-
lene at 0 °C provided the insertion complex cis-Pt(CHd
CHSiPh3)(SiPh3)(PMe2Ph)2 (2e), which was isolated in
86% yield. The formation of insertion complex was also
noted with 1-hexyne (3 equiv), but its isolation was
unsuccessful due to decomposition.
temperature (-70 °C). Therefore, we may consider that
the structural features observed in the crystals are
preserved in solution as well.
Rea ction s w ith Alk yn es a n d Alk en es. Complexes
1a -c instantly reacted with phenylacetylene (1 equiv)
at room temperature in CH2Cl2 to give the correspond-
ing insertion complexes 2a -c in quantitative yields as
confirmed by 31P{1H} NMR spectroscopy (eq 1). Complex
1d was much less reactive, but underwent the insertion
of 1 equiv of phenylacetylene within 10 min at 60 °C in
benzene in the presence of an excess amount of phenyl-
acetylene (5 equiv).
Complexes 2a -d were isolated as white solids and
characterized by NMR spectroscopy and elemental
analysis. The occurrence of regioselective insertion of
phenylacetylene, leading to the form of cis-Pt{C(Ph)d
CH(SiR3)}(SiR3)(PMe2Ph)2, was confirmed by compari-
son of the NMR data of 2a -d with those of cis-
PtMe{C(Ph)dCH(SiPh3)}(PMe2Ph)2, whose structure
was previously determined by X-ray analysis.6 For
example, the â-hydrogen of the alkenyl ligand in 2a
Figure 3 shows the X-ray structure of 2e. The
platinum atom is in a slightly distorted square planar
environment; the sum of four angles about platinum is
358.6°. The C1-C2 distance (1.338(8) Å) is in the typical
range of a carbon-carbon double bond. The Pt-C1-
C2 and C1-C2-Si1 angles (139.7(5) and 132.9(5)°,
respectively) are considerably wider than typical sp2
carbons, probably due to steric reasons. The cis ar-
(16) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem. Rev.
1973, 10, 335. Bresciani-Pahor, N.; Forcolin, M.; Marzilli, L. G.;
Randaccio, L.; Summers, M. F.; Toscano, P. J . Coord. Chem. Rev. 1985,
63, 1.

Phenylacetylene Insertion into (SiR3)2-Pt Complexes
Organometallics, Vol. 17, No. 26, 1998 5633
Ta ble 2. P seu d o-F ir st-Or d er Ra te Con sta n ts a n d
Kin etic P a r a m eter s for th e In ser tion of
P h en yla cetylen e in to Bis(silyl) Com p lexes 1a -d a
1a (at -5 °C) kobsd ) 1.15 × 10-4 s-1
∆Gq ) 20.5 kcal mol-1
∆Hq ) 25.4(4) kcal mol-1 ∆Sq ) 18.4(2) eu
1b (at -5 °C) kobsd ) 4.11 × 10-5 s-1
1c (at -5 °C)b kobsd ) 1.18 × 10-3 s-1
∆Gq ) 21.0 kcal mol-1
∆Hq ) 29.8(4) kcal mol-1 ∆Sq ) 32.9(2) eu
∆Gq ) 19.2 kcal mol-1
∆Hq ) 26.6(9) kcal mol-1 ∆Sq ) 27.5(3) eu
1d (at +50 °C) kobsd ) 8.08 × 10-4 s-1
a
All kinetic runs were conducted in CD2Cl2 except for 1d
(CDCl3). Initial concentration: [complex] ) 20-25 mM, [PhCtCH]
) 0.50 M. The activation parameters were estimated from Eyring
plots in the temperature range: -10 to +5 °C for 1a (r ) 0.999),
-5 to +10 °C for 1b (r ) 1.00), -25 to -10 °C for 1c (r ) 0.999).
b
The rate constant at -5 °C was extrapolated from the Eyring
plot.
rangement of the platinum and silicon atoms around
the CdC double bond clearly shows the occurrence of
cis insertion of acetylene into the Pt-Si bond.
F igu r e 4. Effect of added PMe2Ph on the insertion rate
of phenylacetylene into 1b in CD2Cl2 at -5 °C. Initial
concentration: [1b] ) 0.025 M; [PhCtCH] ) 0.25 M.
Kin etic Stu d y on th e In ser tion of P h en yla cety-
len e. Time courses of the reactions of 1a -d with
phenylacetylene in CD2Cl2 (for 1a -c) or CDCl3 (for 1d )
were followed by NMR spectroscopy. In the presence of
an excess amount of phenylacetylene (>10 equiv), all
reactions obeyed first-order kinetics with respect to the
concentration of starting complexes over 70% conver-
sion. Table 2 lists the rate constants together with the
activation parameters for 1a -c, showing the following
reactivity order: 1c > 1a > 1b . 1d . The lowest
reactivity of 1d is probably due to the strongest Pt-
SiFPh2 bond; the M-Si bond energy is known to
increase with increasing electron affinity of the silyl
ligand, which is enhanced by electron-withdrawing
substituents at silicon.9c On the other hand, the reactiv-
ity order observed for 1a -c are apparently inconsistent
with the electronic nature of silyl ligands. To examine
the reason for this irregularity, we next carried out
detailed kinetic experiments on the insertion mecha-
nism.
Dependence of the reaction rate of 1b on the concen-
tration of PMe2Ph and PhCtCH added to the system
is shown in Figures 4 and 5, respectively. The reaction
progress was retarded by addition of free PMe2Ph to the
system; reciprocals of the rate constants were linearly
correlated with the concentration of PMe2Ph added to
the system (r ) 0.989; Figure 4). Furthermore, a good
linear correlation was observed between the 1/kobsd and
1/[PhCtCH] values (r ) 1.00; Figure 5).17
F igu r e 5. Effect of phenylacetylene concentration on the
insertion rate of phenylacetylene into 1b in CD2Cl2 in the
presence of added PMe2Ph at -5 °C. Initial concentration:
[1b] ) 0.025 M; [PMe2Ph] ) 2.5 mM.
converted to the final product 2b by trans to cis
isomerization followed by coordination of PMe2Ph liber-
ated in the system.
In this scheme, steady-state approximation for the
concentration of 3b leads to the following equation:
These kinetic observations are consistent with the
insertion mechanism depicted in Scheme 1 (SiR3
)
SiMePh2). The first step is dissociation of one of the
PMe2Ph ligands (L) from 1b to give the three-coordinate
bis(silyl) intermediate 3b, which successively undergoes
migratory insertion of phenylacetylene into the Pt-
SiMePh2 bond via prior coordination of phenylacetylene
to the vacant site of 3b. The resulting 4b is then rapidly
d[3b]/dt ) k1[1b] - k-1[PMe2Ph][3b] -
k2[PhCtCH][3b] ) 0 (2)
Thus
k1[1b]
[3b] )
(3)
(17) Kinetic experiments for Figure 5 were conducted in the presence
of added PMe2Ph (2.5 mM) to maintain a constant concentration of
free PMe2Ph in the reaction system. In the kinetic runs at a low
concentration of phenylacetylene ([PhCtCH] ) 0.125 and 0.150 M),
the effect of change in the acetylene concentration could not be ignored
at the later stage of the reaction. Therefore, the rate constants were
estimated from the kinetic data at low conversion of 1b (up to 40.9%
conversion at 0.125 M.; up to 51.4% conversion at 0.150 M). The first-
order plots exhibited good linear correlations (r ) 1.00 for 16 data
points at 0.125 M.; r ) 0.999 for 16 data points at 0.150 M).
k-1[PMe2Ph] + k2[PhCtCH]
If the steady state for 3b holds and the conversion of
4b to 2b is a rapid process, the formation rate of 2b is
expressed as
d[2b]/dt ) - d[1b]/dt ) k2[PhCtCH][3b] (4)

5634 Organometallics, Vol. 17, No. 26, 1998
Ozawa and Kamite
Ta ble 3. Ra te Con sta n ts in Sch em e 1 for 1a -ca
Sch em e 1a
1a (at -5 °C) k1 ) 1.46(3) × 10-4 s-1 k2/ k-1 ) 1.35(9) × 10-2
1b (at +10 °C) k1 ) 1.8(1) × 10-3 s-1 k2/ k-1 ) 1.48(9) × 10-3
1c (at -5 °C)
k1 ) 2.8(11) × 10-3 s-1 k2/ k-1 ) 4.1(13) × 10-4
a
The values were estimated from the 1/kobsd - 1/[PhCtCH]
plots, examined in CD2Cl2 in the presence of added PMe2Ph (2.5
mM).
SiMePh2 bond. The resulting 4b is rapidly converted to
the final product 2b via the same process as Scheme 1.
In this mechanism, concentration of 5b at time t is
given by the following equation when the equilibration
between 1b and 5b is rapid enough to keep the equi-
librium constant K ) [5b][PMe2Ph]/[1b][PhCtCH],
irrespective of the reaction progress:
K[PhCtCH]
[5b] )
[Pt(SiMePh2)2]total
a
SiR3 ) SiMe2Ph (a), SiMePh2 (b), SiPh3 (c); L ) PMe2Ph.
[PMe2Ph] + K[PhCtCH]
(7)
Sch em e 2a
where [Pt(SiMePh2)2]total ) [1b] + [5b]. Therefore, the
formation rate of 2b is expressed as
d[2b]
dt
d
) - [Pt(SiMePh2)2]total ) k[5b]
dt
kK[PhCtCH]
)
[Pt(SiMePh2)2]total
[PMe2Ph] + K[PhCtCH]
(8)
(9)
The kobsd value is given by the following equation:
[PMe2Ph]
1
1
)
+
kobsd
k
kK[PhCtCH]
On the basis of eq 9 as well as the slopes and
intercepts of Figures 4 and 5, the equilibrium constant
K in Scheme 2 is estimated as 1.48 × 10-3; the value
corresponds to the [5b]/[1b] ratio of 0.074-0.592 under
the reaction conditions ([PhCtCH] ) 0.125-1.00 M,
[PMe2Ph] ) 2.5 mM). Thus, 5b must be detected by
NMR spectroscopy. However, 31P{1H} NMR spectra of
the reaction solutions exhibited no signals assignable
to 5b, and only the signals of 1b and 2b appeared
without broadening. Consequently, possibility of the
mechanism in Scheme 2 can be excluded.
Complexes 1a and 1c showed kinetic behavior very
similar to 1b. Thus, the reaction progress was retarded
by addition of free PMe2Ph to the systems,18 and the
1/kobsd and 1/[PhCtCH] values were linearly correlated
with each other for both systems (r ) 0.997 for 1a and
0.998 for 1c). Table 3 summarizes the k1 and k2/k-1
values for the mechanism in Scheme 1, which were
estimated from the 1/kobsd - 1/[PhCtCH] plots. The
data for 1a and 1c were obtained at -5 °C. The reaction
of 1b was too slow to be examined at this temperature
and examined at 10 °C.
a
L ) PMe2Ph.
Substitution of eq 3 into eq 4 yields the final rate
expression:
k1k2[PhCtCH]
d[1b]
dt
-
)
[1b] (5)
k-1[PMe2Ph] + k2[PhCtCH]
Accordingly, the following relation between the kobsd
value and the concentration of PMe2Ph and phenyl-
acetylene can be obtained:
k-1[PMe2Ph]
1
kobsd
1
)
+
(6)
k1
k1k2[PhCtCH]
Equation 6 is fully consistent with the kinetic data.
Thus the k-1/k1k2 values, which are calculated on the
basis of the slopes in Figures 4 and 5, are in good
agreement with each other: 3.8 × 105 and 3.76 × 105 s.
Furthermore, reciprocals of the intercepts in these
figures, which correspond to the rate constant (k1) for
the dissociation of PMe2Ph ligand from 1b, are in
agreement with each other: 1.9 × 10-3 and 1.8 × 10-3
P r ep a r a tion a n d Rea ction of cis-P t(SiMe2P h )-
(SiP h 3)(P Me2P h )2 (1f). It has been found that the
SiPh3 complex 1c undergoes the insertion of phenyl-
acetylene more rapidly than the SiMe2Ph complex 1a .
To examine the reason for the difference between the
s-1
.
On the other hand, the kinetic relations observed in
Figures 4 and 5 also accord with the mechanism in
Scheme 2, in which rapid equilibrium between 1b and
5b via ligand substitution is presumed prior to the rate-
determining insertion of phenylacetylene into the Pt-
(18) The rate constants in the absence and presence of free PMe2-
Ph (5.0 mM) are as follows: [1a ] 1.21 × 10-4 and 0.82 × 10-4 s-1; [1c]
1.18 × 10-3 and 1.10 × 10-4 s-1 (in CD2Cl2, at -5 °C, [PhCtCH] )
0.50 M).

Phenylacetylene Insertion into (SiR3)2-Pt Complexes
Organometallics, Vol. 17, No. 26, 1998 5635
Ch a r t 1
reaction rates, we next attempted to compare the
reactivity of Pt-SiMe2Ph and Pt-SiPh3 bonds more
directly with the unsymmetrical bis(silyl) complex cis-
Pt(SiMe2Ph)(SiPh3)(PMe2Ph)2 (1f).
Reaction of 1c with HSiMe2Ph (1 equiv) in benzene
at room temperature for 10 min gave a mixture of 1f,
1c, and 1a in a 98.1:1.7:0.2 ratio (eq 10). Recrystalli-
zation of the product provided a mixture of 1f and 1c
in a 97:3 ratio. Several attempts to obtain pure 1f were
unsuccessful. Thus, repeated recrystallizations led to
the higher content of 1c. Elongated reaction time
afforded a complex mixture of silylplatinum complexes
including cis-PtH(SiPh3)(PMe2Ph)2. When 1a was treated
with HSiPh3, nearly half of 1a remained unreacted.
than 1c (k2(1a ) > k2(1c)).19 The higher reactivity of the
Pt-SiMe2Ph bond than the Pt-SiPh3 bond was also
suggested by the reaction of unsymmetrical bis(silyl)
complex 1f (eq 11). These data are in accord with the
assumption that the weaker Pt-Si bond possesses the
higher reactivity toward insertion. However, even in this
situation, 1c reacts more rapidly with phenylacetylene
than 1a . This is because 1c undergoes the dissociation
of PMe2Ph more readily than 1a (compare the k1 values
in Table 3). The k1 value for 1b with the least reactivity
was 1.8 × 10-3 s-1 at 10 °C, which corresponds to the
approximate value of 0.9 × 10-4 s-1 at -5 °C on the
basis of activation parameters. Thus, it is concluded that
the reactivity order observed for 1a -c is mainly due to
the difference between the dissociation rates of PMe2-
Ph.
One may expect that the rate of dissociation is
affected by bulkiness and the trans influence of silyl
ligands; the former facilitates the dissociation by steric
congestion around platinum in the order 1a < 1b < 1c
and the latter by weakening the Pt-P bonds in the
order 1c < 1b < 1a .20 However, neither factor is
correlated with the reactivity order observed (1c > 1a
> 1b). The reason for this disagreement can be seen in
the X-ray structures. Thus, it has been found that bis-
(silyl) complexes have the structures significantly dis-
torted from planarity in the order 1a < 1c < 1b (Table
1). Similarly to cis-MR2L2 of group 10 metals (R ) alkyl,
L ) tertiary phosphine),21 the silyl ligands in 1a -c
combine with the Pt(PMe2Ph)2 moiety via two types of
bonding orbitals in Chart 1. The a1 and b2 symmetry
orbitals in this scheme are roughly assigned to donation
(σ f d) and back-donation (d f σ*) interactions between
the combination of two SiR3 ligands and the platinum
center, respectively. Unlike the dialkyl complexes, the
present complexes have silyl ligands, which are much
more electron-releasing than alkyl ligands. Therefore,
the a1 type orbital interaction can predominate over the
b2 type interaction. In this situation, the bis(silyl)
complex has a significantly distorted structure when the
distortion is needed to relieve the steric repulsion
between the ligands. The higher distortion in 1b than
1a can be rationalized in this context, where the
sterically more demanding SiMePh2 ligands leads to the
more twisted structure.22 The steric strain inherent in
1b is effectively relieved by this distortion. In addition,
Treatment of the above mixture of 1f and 1c (97:3)
with phenylacetylene (10 equiv) in CD2Cl2 at room
temperature provided four kinds of products A-D in a
90:4:3:3 A:B:C:D ratio (eq 11). Product D was 2c derived
from 1c, as confirmed by 31P{1H} NMR spectroscopy.
Products B and C could not be identified due to their
low contents. On the other hand, the main product A
was characterized by NMR spectroscopy as cis-Pt-
{C(Ph)dCH(SiMe2Ph)}(SiPh3)(PMe2Ph)2 (2f), which is
formed by the insertion of phenylacetylene into the Pt-
SiMe2Ph bond of 1f. Thus, the higher reactivity of Pt-
SiMe2Ph bond than Pt-SiPh3 bond was evidenced.
Discu ssion
We have found the following reactivity order of bis-
(silyl)platinum complexes toward the insertion of phen-
ylacetylene: 1c > 1a > 1b . 1d . The lowest reactivity
of 1d may be attributed to the relatively inert nature
of the Pt-SiFPh2 bond, caused by the strongest Pt-Si
bond (vide supra). On the other hand, the reactivity
order observed for 1a -c (i.e. 1c > 1a > 1b) is appar-
ently inconsistent with the expected order of Pt-Si bond
strength. This reason will be discussed in the following
section. At the beginning we will analyze the rate
constants estimated by kinetic experiments.
(19) Since 1a is less prone to dissociation of the PMe2Ph ligand than
1c due to steric reasons (see text), the relative magnitude of the k-1
values is considered to be 1a > 1c. Accordingly, the relative order k2-
(1a ) > k2(1c) can be estimated from the k2/k-1 values in Table 3.
(20) Sakaki et al. recently reported that the more σ-donating silyl
ligand possesses the higher trans influence.9a
(21) Albright, T. A.; Burdett, J . K.; Whangbo, M.-H. Orbital Interac-
tions in Chemistry; Wiley: New York, 1985. Tatsumi, K.; Hoffmann,
R.; Yamamoto, A.; Stille, J . K. Bull. Chem. Soc. J pn. 1981, 54, 1857.
(22) Note that the P-Pt-P angle of the most twisted 1b is
significantly wider than that of 1a and 1c (Table 1), indicating the
least contribution of the b2 type orbital interaction in 1b.21
As seen from Table 3, the k2/k-1 ratio for 1a is 33
times as large as that for 1c at -5 °C, probably because
the insertion of phenylacetylene into the Pt-SiR3 bond
(i.e., 3 f 4 in Scheme 1) proceeds more rapidly for 1a

5636 Organometallics, Vol. 17, No. 26, 1998
Ozawa and Kamite
8 Hz, 2J Pt-C ) 74 Hz, SiCH3), 15.7 (dd, 1J P-C ) 23 Hz, 3J P-C
)
the distortion also reduces the direct trans influence of
12 Hz, 2J Pt-C ) 23 Hz, PCH3), 126.8 (s, Ph), 127.2 (s, Ph), 128.2
the silyl ligands on the Pt-P bonds. Indeed, 1b has the
2
1
(s, Ph), 129.2 (s, Ph), 130.4 (s, Ph), 134.6 (d, J P-C ) 10 Hz,
shortest Pt-P bonds and the largest J Pt-P constant
Ph), 141.2 (m, Ph), 152.7 (m, Ph). 31P{1H} NMR (CD2Cl2, -70
(Table 1). These situations give rise to the stability of
1b toward the dissociation of PMe2Ph and reduce the
insertion rate.
1
2
°C): δ -6.4 (s, J Pt-P ) 1542 Hz, J Si-P(transoid) ) 154 Hz,
2J Si-P(cisoid) ) 19 Hz, J P-P ) 23 Hz). Anal. Calcd for C32H44
-
2
Si2P2Pt: C, 51.81; H, 5.98. Found: C, 51.95; H, 5.98.
On the other hand, when the silyl ligand has electron-
withdrawing (or less electron-releasing) substituents
and possesses an electron-withdrawing character, the
b1 type orbital interaction gains importance, compelling
the planarity of the bis(silyl) complex. Complex 1c
should be the case, in which the distortion is modest
despite the presence of the most sterically demanding
SiPh3 ligands. This situation must provide significant
strain energy for 1c, which will be efficiently released
by dissociation of one of the PMe2Ph ligands. Further-
more, the more planar structure causes the more
effective weakening of the Pt-P bonds by silyl ligands
with great trans influence; 1c actually has the longest
Complex 1b was prepared according to literature.10 The H
1
and 13C{1H} NMR data hitherto unpublished are as follows.
1H NMR (CD2Cl2): δ 0.42 (s, J Pt-H ) 30.3 Hz, 6H, SiCH3),
3
2
3
0.55 (d, J P-H ) 8.3 Hz, J Pt-H ) 12.2 Hz, 12H, PCH3), 7.18-
7.44 (m, 22H, Ph), 7.73 (dd, 8H, Ph). 13C{1H} NMR (CD2Cl2):
2
1
2
δ 6.4 (s, J Pt-C ) 88 Hz, SiCH3), 15.6 (d, J P-C ) 25 Hz, J Pt-C
) 25 Hz, PCH3), 127.2 (s, Ph), 127.4 (s, Ph), 128.5 (t, Ph), 129.5
3
(s, Ph), 130.5 (t, Ph), 136.5 (s, J Pt-C ) 20 Hz, Ph), 140.8 (m,
Ph), 148.5 (m, Ph). The 31P{1H} NMR data are reported in ref
11a.
P r ep a r a tion of cis-P t(SiP h 3)2(P Me2P h )2 (1c). To a solu-
10a
tion of trans-PtCl(SiPh3)(PMe2Ph)2
(1.20 g, 1.57 mmol) in
THF (10 mL) was added a THF solution of Ph3SiLi (0.34 M,
5.8 mL, 1.97 mmol) at room temperature. The mixture was
stirred at room temperature for 30 min. Methanol (0.1 mL)
was added, and the solution was concentrated to dryness by
pumping. The resulting solid was extracted with benzene (5
mL × 3) and filtered through a filter-paper-tipped cannula.
The combined extracts were concentrated to dryness to give a
yellow solid of 1c, which was washed with Et2O (3 mL × 2) at
room temperature and dried under vacuum (1.44 g, 93%). This
product was spectroscopically pure. The analytically pure
complex was obtained by recrystallization from CH2Cl2/Et2O
1
Pt-P bonds and the smallest J Pt-P constant (Table 1).
Consequently, 1c is highly reactive to the dissociation
of PMe2Ph and hence to the insertion of phenylacety-
lene.
In conclusion, we have found an interesting relation
between the reactivities and the structures of bis(silyl)-
platinum complexes. The reactivity toward the insertion
of phenylacetylene is mainly dictated by the ease of
dissociation of the PMe2Ph ligand. The dissociation rates
exhibit rather intricate dependence on the sorts of silyl
ligands because the bis(silyl) complexes have distorted
structures and the distortion is highly sensitive to the
steric and electronic nature of the silyl ligands.
2
(63%). 1H NMR (CD2Cl2, 23 °C): δ 0.52 (d, J P-H ) 7.8 Hz,
3J Pt-H ) 11.5 Hz, 12H, PCH3), 7.04-7.14 (m, 18H, Ph), 7.37-
7.50 (m, 10H, Ph), 7.65 (dd, 12H, Ph). 13C{1H} NMR (CD2Cl2,
23 °C): δ 16.0 (s, PCH3), 126.7 (s, Ph), 127.3 (s, Ph), 128.8 (s,
Ph), 129.8 (s, Ph), 130.7 (s, Ph), 137.9 (s, Ph), 140.2 (m, Ph),
2
144.9 (s, J Pt-C ) 48 Hz, Ph). 31P{1H} NMR (CD2Cl2, -70 °C):
1
2
2
δ -9.7 (s, J Pt-P ) 1536 Hz, J Si-P(transoid) ) 159 Hz, J Si-P(cisoid)
Exp er im en ta l Section
2
) 19 Hz, J P-P ) 23 Hz). Anal. Calcd for C52H52Si2P2Pt: C,
63.08; H, 5.29. Found: C, 62.59; H, 5.28.
Gen er a l P r oced u r e. All manipulations were carried out
under a nitrogen atmosphere using conventional Schlenk
techniques. Nitrogen gas was dried by passing through P2O5
(Merck, SICAPENT). NMR spectra were recorded on a J EOL
J NM-A400 or Varian Mercury 300 spectrometer. Chemical
shifts are reported in δ (ppm) referred to an internal SiMe4
standard for 1H and 13C NMR and to an external 85% H3PO4
standard for 31P NMR. GLC analysis was performed with a
GL Sciences GC-353 instrument equipped with a FID detector
and a capillary column (TC-1, 30 m). GC-mass analyses were
conducted with a Shimadzu QP-5000 GC-mass spectrometer
(EI, 70 eV). THF, Et2O, and benzene were dried over sodium
benzophenone ketyl and distilled prior to use. CH2Cl2 was
dried over CaH2 and distilled prior to use. CD2Cl2 was dried
over LiAlH4, vacuum transferred, and stored under a nitrogen
atmosphere.
P r ep a r a tion of cis-P t(SiF P h 2)2(P Me2P h )2 (1d ). To a
solution of cis-PtMe(SiPh3)(PMe2Ph)26 (230 mg, 0.31 mmol) in
benzene (10 mL) was added HSiFPh2 (623 mg, 3.08 mmol) at
room temperature. The mixture was stirred at 60 °C for 12 h
and then concentrated to dryness, giving a white solid, which
was washed with hexane (3 mL × 3) at room temperature and
dried under vacuum (230 mg, 85%). The crude product was
dissolved in CH2Cl2 (ca. 1 mL), Et2O (ca. 3 mL) was carefully
layered, and the solvent layers were allowed to stand at room
temperature for 12 h and then at -20 °C for 1 day to give
1
white crystals of 1d (195 mg, 72%). H NMR (CD2Cl2, 23 °C):
δ 1.04 (d, 2J P-H ) 7.8 Hz, 3J Pt-H ) 18.5 Hz, 12H, PCH3), 7.17-
7.31 (m, 16H, Ph), 7.32-7.40 (m, 6H, Ph), 7.61 (dd, 8H, Ph).
13C{1H} NMR (CD2Cl2, 23 °C): δ 16.5 (d, 1J P-C ) 30 Hz, 2J Pt-C
) 26 Hz, PCH3), 124.7 (s, Ph), 128.5 (s, Ph), 128.7 (t, Ph), 130.0
(s, Ph), 130.7 (t, Ph), 135.7 (s, Ph), 139.1 (m, PPh), 144.9(m,
P r ep a r a t ion of cis-P t (SiMe2P h )2(P Me2P h )2 (1a ). To a
suspension of cis-PtCl2(PMe2Ph)2 (2.61 g, 4.81 mmol) in THF
(25 mL) was added a solution of PhMe2SiLi in THF (1.17 M,
9.1 mL, 10.6 mmol) at room temperature by means of a
syringe. The mixture was stirred at room temperature for 30
min. Methanol (0.1 mL) was added, and the solution was
concentrated to dryness. The residue was extracted with
benzene (50 mL × 3) and filtered through a filter-paper-tipped
cannula. The combined extracts were concentrated to dryness
to give a yellow solid of 1a , which was washed with Et2O (3
mL × 2) at room temperature and dried under vacuum (1.98
g, 55%). This product was analytically pure. The crystalline
product could be obtained by recrystallization from CH2Cl2/
1
Ph). 31P{1H} NMR (CD2Cl2, 23 °C): δ -4.3 (t, J Pt-P ) 1522
2
3
Hz, J Si-P ) 76 Hz, J F-P ) 35 Hz). Anal. Calcd for C40H42F2-
Si2P2Pt: C, 54.97; H, 4.94. Found: C, 54.73; H, 4.64.
P r epa r a tion of cis-P t{C(P h )dCH(SiMe2P h )}(SiMe2P h )-
(P Me2P h )2 (2a ). While the insertion of phenylacetylene into
1a proceeded quantitatively with 1 equiv of the acetylene in
NMR scale, the following experiment in preparative scale was
conducted with a slightly excess amount (1.5 equiv) of phen-
ylacetylene. To a solution of cis-Pt(SiMe2Ph)2(PMe2Ph)2 (1a ,
529 mg, 0.71 mmol) in CH2Cl2 (9 mL) was added phenylacety-
lene (117 µL, 1.07 mmol) at 0 °C. The mixture was stirred at
room temperature for 15 min and then concentrated to
dryness. The resulting solid of 2a was washed with a mixture
of Et2O and MeOH (1:10) (5 mL × 3) at -78 °C and dried under
3
Et2O. 1H NMR (CD2Cl2, 23 °C): δ 0.51 (s, J Pt-H ) 26.8 Hz,
2
3
12H, SiCH3), 0.74 (d, J P-H ) 7.3 Hz, J Pt-H ) 16.6 Hz, 12H,
1
PCH3), 7.12-7.18 (m, 2H, Ph), 7.20-7.37 (m, 14H, Ph), 7.63
vacuum (352 mg, 58%). H NMR (CD2Cl2, -20 °C): δ 0.05 (s,
3
3
(dd, 4H, Ph). 13C{1H} NMR (CD2Cl2, 23 °C): δ 6.8 (t, J P-C
)
3J Pt-H ) 24.8 Hz, 3H, PtSiCH3), 0.43 (s, J Pt-H ) 22.8 Hz, 3H,

Phenylacetylene Insertion into (SiR3)2-Pt Complexes
Organometallics, Vol. 17, No. 26, 1998 5637
1
PtSiCH3), 0.60 (s, 3H, PtCdCSiCH3), 0.81 (s, 3H, PtCd
CSiCH3), 0.89 (d, 2J P-H ) 8.0 Hz, 3J Pt-H ) 23.2 Hz, 3H, PCH3),
2J P-C ) 10 Hz, PPh), 136.0 (d, J P-C ) 16 Hz, PPh), 136.3-
2
2
138.2 (m, Ph), 144.7 (s, J Pt-C ) 50 Hz, SiPh), 154.1 (d, J Pt-C
) 33 Hz, PtC(Ph)dC), 182.9 (dd, 1J Pt-C ) 770 Hz, 2J P-C ) 100
and 16 Hz, PtCdCH). 31P{1H} NMR (CD2Cl2, -20 °C): δ -14.4
2
3
0.96 (d, J P-H ) 8.0 Hz, J Pt-H ) 19.2 Hz, 3H, PCH3), 1.01 (d,
3
2
2J P-H ) 8.0 Hz, J Pt-H ) 14.4 Hz, 3H, PCH3), 1.20 (d, J P-H
)
3
2
1
2
8.0 Hz, J Pt-H ) 22.4 Hz, 3H, PCH3), 6.89 (t, 2H, Ph), 7.0-7.4
(m, 17H, Ph), 7.55 (dd, 4J P-H ) 18.4 and 4.4 Hz, 3J Pt-H ) 134.3
Hz, 1H, PtCdCH), 7.60-7.75 (m, 4H, Ph), 8.00 (d, 2H, Ph).
13C{1H} NMR (CD2Cl2, -20 °C): δ 0.3 (s, PtCdCSiCH3), 0.9
(d, J P-P ) 20 Hz, J Pt-P ) 1246 Hz, J Si-P ) 174 Hz), -17.9
2 1
(d, J P-P ) 20 Hz, J Pt-P ) 1820 Hz). Anal. Calcd for C60H58
-
Si2P2Pt: C, 65.97; H, 5.35. Found: C, 65.88; H, 5.20.
P r ep a r a tion of cis-P t{C(P h )dCH(SiF P h 2)}(SiF P h 2)-
(P Me2P h )2 (2d ). To a solution of cis-Pt(SiFPh2)2(PMe2Ph)2
(230 mg, 0.26 mmol) in C6H6 (5 mL) was added phenylacety-
lene (145 µL, 1.32 mmol) at room temperature. The mixture
was stirred at 60 °C for 10 min and concentrated to dryness
to give a white solid of 2d , which was washed with hexane (3
mL × 3) at room temperature and dried under vacuum (242
3
2
(s, PtCdCSiCH3), 4.7 (d, J P-C ) 8 Hz, J Pt-C ) 63 Hz,
PtSiCH3), 6.2 (s, 2J Pt-C ) 69 Hz, PtSiCH3), 12.5 (d, 1J P-C ) 23
2
1
2
Hz, J Pt-C ) 16 Hz, PCH3), 14.3 (d, J P-C ) 26 Hz, J Pt-C ) 27
Hz, PCH3), 16.1 (dd, J P-C ) 28 Hz, J P-C ) 5 Hz, J Pt-C ) 30
Hz, PCH3), 16.7 (dd, J P-C ) 31 Hz, J P-C ) 5 Hz, J Pt-C ) 30
Hz, PCH3), 125.9 (s, PtCdCH), 126.9 (s, Ph), 127.0 (s, Ph),
127.1 (s, Ph), 127.4 (s, Ph), 127.6 (s, Ph), 128.1 (s, Ph), 128.2
(s, Ph), 128.3 (s, Ph), 129.1 (s, Ph), 129.3 (s, Ph), 129.5 (s, 3J Pt-C
1
3
2
1
3
2
1
2
mg, 94%). H NMR (CD2Cl2, -20 °C): δ 0.58 (d, J P-H ) 7.6
Hz, 3J Pt-H ) 16.0 Hz, 3H, PCH3), 0.98 (d, 2J P-H ) 8.8 Hz, 3J Pt-H
2
2
2
3
) 46 Hz, Ph), 130.3 (d, J P-C ) 10 Hz, PPh), 130.4 (d, J P-C
)
) 17.6 Hz, 3H, PCH3), 1.09 (d, J P-H ) 8.4 Hz, J Pt-H ) 21.6
10 Hz, PPh), 134.0 (s, Ph), 134.8 (s, 3J Pt-C ) 21 Hz, Ph), 137.7
2
3
Hz, 3H, PCH3), 1.32 (d, J P-H ) 8.8 Hz, J Pt-H ) 23.2 Hz, 3H,
PCH3), 6.86-7.00 (m, 4H, Ph), 7.04-7.46 (m, 25H, Ph, PtCd
CH), 7.54 (dd, Ph), 7.67-7.82 (m, 4H, Ph). 13C{1H} NMR
1
1
3
(d, J P-C ) 30 Hz, PPh), 138.6 (dd, J P-C ) 41 Hz, J P-C ) 5
3
Hz, PPh), 142.5 (s, PtCdCSiPh), 150.9 (dd, J P-C ) 8 and 5
2
3
2
1
4
Hz, J Pt-C ) 58 Hz, PtSiPh), 152.9 (d, J P-C ) 5 Hz, J Pt-C
)
(CD2Cl2, -20 °C): δ 11.9 (dd, J P-C ) 25 Hz, J F-C ) 13 Hz,
PCH3), 13.8 (dd, J P-C ) 28 Hz, J F-C ) 15 Hz, PCH3), 16.1
(dd, J P-C ) 31 Hz, J F-C ) 16 Hz, PCH3), 14.9 (m, PCH3),
120.7 (m, PtCdCH), 126.5 (s, Ph), 126.8 (s, Ph), 127.0 (s, Ph),
127.3 (s, Ph), 127.6 (s, Ph), 127.9 (s, Ph), 128.0 (s, Ph), 128.2
(s, Ph), 128.3 (s, Ph), 129.3 (s, Ph), 129.4 (s, Ph), 129.5 (s, Ph),
129.6 (s, Ph), 129.9 (s, Ph), 130.6 (s, Ph), 130.6 (s, Ph), 134.2
2
1
4
40 Hz, PtC(Ph)dC), 181.5 (dd, J P-C ) 99 and 15 Hz, PtCd
CH). 31P{1H} NMR (CD2Cl2, -20 °C): δ -12.2 (d, J P-P ) 19
2
1
4
1
2
2
Hz, J Pt-P ) 1210 Hz, J Si-P ) 167 Hz), -15.2 (d, J P-P ) 19
Hz, 1J Pt-P ) 1885 Hz). Anal. Calcd for C40H50Si2P2Pt: C, 56.92;
H, 5.97. Found: C, 56.68; H, 5.78.
P r epa r a tion of cis-P t{C(P h )dCH(SiMeP h 2)}(SiMeP h 2)-
(P Me2P h )2 (2b) a n d cis-P t{C(P h )dCH(SiP h 3)}(SiP h 3)-
(P Me2P h )2 (2c). The title compounds were prepared similarly
to 2a using 1b or 1c in place of 1a and isolated as white solids
in 76 (2b) and 83% (2c) yields.
2
(d, J P-C ) 12 Hz, PPh), 134.5 (s, Ph), 134.8 (s, Ph), 135.1 (d,
2J P-C ) 30 Hz, PPh), 136.6 (d, J P-C ) 69 Hz, PPh), 136.7 (d,
1
1J P-C ) 69 Hz, PPh), 136.9 (d, J P-C ) 48 Hz, PPh), 137.4 (d,
1
1J P-C ) 43 Hz, PPh), 144.9 (m, PtCdCSiPh), 146.1 (t, 2J Pt-C
)
3
2
1
4
102 Hz, PtSiPh), 151.4 (d, J P-C ) 3 Hz, J Pt-C ) 40 Hz, PtC-
Compound 2b. H NMR (CD2Cl2, -20 °C): δ 0.53 (d, J P-P
) 2.0 Hz, 3J Pt-H ) 24.4 Hz, 3H, PtSiCH3), 0.72 (d, 2J P-H ) 7.2
Hz, 3J Pt-H ) 15.2 Hz, 3H, PCH3), 0.87 (d, 2J P-H ) 7.6 Hz, 3J Pt-H
2
1
(Ph)dC), 188.6 (dd, J P-C ) 94 and 15 Hz, J Pt-C ) 750 Hz,
PtCdCH). 31P{1H} NMR (CD2Cl2, -20 °C): δ -9.2 (dd, J P-P
2
3
1
2
2
3
) 22 Hz, J F-P ) 43 Hz, J Pt-P ) 1337 Hz, J Si-P ) 199 Hz),
) 19.0 Hz, 3H, PCH3), 1.01 (d, J P-H ) 8.4 Hz, J Pt-H ) 17.2
2
3
1
2
3
-13.2 (dd, J P-P ) 22 Hz, J F-P ) 9 Hz, J Pt-P ) 1819 Hz).
Anal. Calcd for C48H48F2Si2P2Pt: C, 59.06; H, 4.96. Found: C,
58.69; H, 4.78.
Hz, 3H, PCH3), 1.13 (d, J P-H ) 7.6 Hz, J Pt-H ) 19.6 Hz, 3H,
PCH3), 1.43 (s, 3H, PtCdCSiCH3), 6.75 (t, 2H, Ph), 6.85-7.45
4
(m, 16H, Ph), 7.55-7.80 (m, 9H, Ph), 7.80 (dd, J P-H ) 18.8
and 3.6 Hz, J Pt-H ) 130.3 Hz, 1H, PtCdCH). 13C{1H} NMR
P r ep a r a tion of cis-P t(CHdCHSiP h 3)(SiP h 3)(P Me2P h )2
(2e). Complex 1c (376 mg, 0.38 mmol) was placed in a 50 mL
Schlenk tube and dissolved in CH2Cl2 (1.5 mL) at room
temperature. The system was evacuated and acetylene gas (1
atm) was introduced at 0 °C. The solution was stirred at room
temperature for 15 min and concentrated to dryness by
pumping to give a white solid of 2e, which was washed with
Et2O (3 mL × 3) at -78 °C and dried under vacuum (332 mg,
86%). 1H NMR (CD2Cl2, 0 °C): δ 0.65 (d, 2J P-H ) 8.3 Hz, 3J Pt-H
3
1
(CD2Cl2, -20 °C): δ -1.5 (s, J Si-C ) 53 Hz, PtCdCSiCH3),
3
2
1
4.0 (d, J P-C ) 5 Hz, J Pt-C ) 63 Hz, PtSiCH3), 12.1 (d, J P-C
1
3
2
) 23 Hz, PCH3), 14.6 (d, J P-C ) 28 Hz, J P-C ) 3 Hz, J Pt-C
) 29 Hz, PCH3), 15.4 (d, 1J P-C ) 30 Hz, 2J Pt-C ) 28 Hz, PCH3),
1
3
2
17.0 (d, J P-C ) 30 Hz, J P-C ) 4 Hz, J Pt-C ) 35 Hz, PCH3),
2
123.2 (t, J Pt-C ) 56.2 Hz PtCdCH), 125.8 (s, Ph), 126.9 (s,
Ph), 127.0 (s, Ph), 127.1 (s, Ph), 127.7 (s, Ph), 127.8 (s, Ph),
3
128.1 (t, Ph), 128.5 (s, Ph), 129.0 (s, Ph), 129.1 (s, J Pt-C ) 46
2
2
2
3
Hz, Ph), 130.4 (d, J P-C ) 10 Hz, PPh), 130.5 (d, J P-C ) 10
) 18.5 Hz, 3H, PCH3), 0.81 (d, J P-H ) 7.8 Hz, J Pt-H ) 14.6
2 3
Hz, PPh), 134.4 (s, SiPh), 134.6 (s, SiPh), 135.8 (s, SiPh), 135.9
Hz, 3H, PCH3), 1.05 (d, J P-H ) 7.8 Hz, J Pt-H ) 18.3 Hz, 3H,
2 3
3
1
(s, J Pt-C ) 23 Hz, Ph), 137.5 (d, J P-C ) 31 Hz, PPh), 138.4
PCH3), 1.34 (d, J P-H ) 8.3 Hz, J Pt-H ) 18.1 Hz, 3H, PCH3),
6.84 (m, 2H, Ph), 6.96-7.44 (m, 27H, Ph, PtCdCH), 7.49 (dd,
6H, Ph), 7.58 (dd, Ph), 9.20 (ddd, 3J H-H ) 5.4 Hz, 3J P-H ) 17.6
and 2.4 Hz, PtCHdC). 13C{1H} NMR (CD2Cl2, 0 °C): δ 12.3
1
3
(dd, J P-C ) 41 Hz, J P-C ) 5 Hz, PPh), 140.5 (s, SiPh), 141.1
3
2
(s, SiPh), 146.5 (d, J P-C ) 3 Hz, J Pt-C ) 60 Hz, SiPh), 147.2
3
3
2
(dd, J P-C ) 8 and 3 Hz, SiPh), 152.3 (d, J P-C ) 5 Hz, J Pt-C
2
1
1
1
3
) 36 Hz, PtC(Ph)dC), 182.6 (dd, J P-C ) 97 and 15 Hz, J Pt-C
(d, J P-C ) 20 Hz, PCH3), 15.8 (dd, J P-C ) 30 Hz, J P-C ) 3
2 1 3
) 759 Hz, PtCdCH). 31P{1H} NMR (CD2Cl2, -20 °C): δ -13.1
Hz, J Pt-C ) 30 Hz, PCH3), 16.2 (dd, J P-C ) 30 Hz, J P-C ) 3
2
1
2
2
1
3
(d, J P-P ) 18 Hz, J Pt-P ) 1261 Hz, J Si-P ) 170 Hz), -17.4
Hz, J Pt-C ) 30 Hz, PCH3), 17.1 (dd, J P-C ) 30 Hz, J P-C ) 3
2
1
2
(d, J P-P ) 18 Hz, J Pt-P ) 1853 Hz). Anal. Calcd for C50H54
-
Hz, J Pt-C ) 30 Hz, PCH3), 124.0 (m, PtCdCH), 126.8 (s, Ph),
Si2P2Pt: C, 62.03; H, 5.62. Found: C, 61.68; H, 5.45.
127.1 (s, Ph), 127.6 (s, Ph), 128.2 (t, Ph), 128.9 (s, Ph), 129.2
2
1
2
(s, Ph), 129.4 (s, Ph), 130.5 (d, J P-C ) 12 Hz, PPh), 130.6 (d,
Compound 2c. H NMR (CD2Cl2, -20 °C): δ 0.55 (d, J P-H
2J P-C ) 12 Hz, PPh), 136.7 (s, SiPh), 137.4 (s, J Pt-C ) 20 Hz,
3
3
2
) 8.3 Hz, J Pt-H ) 18.5 Hz, 3H, PCH3), 0.92 (d, J P-H ) 8.3
1
Hz, 3J Pt-H ) 18.1 Hz, 3H, PCH3), 1.03 (d, 2J P-H ) 7.8 Hz, 3J Pt-H
SiPh), 137.7 (s, SiPh), 138.0 (d, J P-C ) 38 Hz, PPh), 138.8
(dd, 1J P-C ) 41 Hz, 3J P-C ) 5 Hz, PPh), 144.8 (d, 3J P-C ) 3 Hz,
2
3
) 15.6 Hz, 3H, PCH3), 1.13 (d, J P-H ) 8.3 Hz, J Pt-H ) 17.1
Hz, 3H, PCH3), 6.53 (t, 2H, Ph), 6.85-7.50 (m, 31H, Ph), 7.56
2J Pt-C ) 50 Hz, SiPh), 179.0 (dd, J P-C ) 98 and 15 Hz, J Pt-C
2
1
) 709 Hz, PtCdCH). 31P{1H} NMR (CD2Cl2, 0 °C): δ -12.3
3
4
4
(d, 6H, Ph), 7.66 (dd, J Pt-H ) 130.8 Hz, J P-H ) 3.9 Hz, J P-H
2
1
2
) 19.5 Hz, 1H, PtCdCH). 13C{1H} NMR (CD2Cl2, -20 °C): δ
(d, J P-P ) 20 Hz, J Pt-P ) 1390 Hz, J Si-P ) 173 Hz), -16.4
2
1
13.7 (d, 1J P-C ) 25 Hz, 2J Pt-C ) 23 Hz, PCH3), 14.5 (d, 1J P-C
)
)
(d, J P-P ) 20 Hz, J Pt-P ) 1821 Hz). Anal. Calcd for C54H54
-
2
1
2
Si2P2Pt: C, 63.82; H, 5.36. Found: C, 63.62; H, 5.20.
26 Hz, J Pt-C ) 29 Hz, PCH3), 16.5 (d, J P-C ) 33 Hz, J Pt-C
33 Hz, PCH3), 16.8 (d, J P-C ) 31 Hz, J Pt-C ) 33 Hz, PCH3),
125.8 (s, PtCdCH), 126.0-127.0 (m, Ph), 127-128 (m, Ph),
128.2 (t, Ph), 128.9 (s, Ph), 129.1 (s, Ph), 129.6 (s, J Pt-C ) 40
Hz, Ph), 130.0 (s, Ph), 130.4 (d, J P-C ) 8 Hz, PPh), 131.3 (d,
1
2
Rea ction s of 1c w ith Eth ylen e a n d 1-Hexyn e. Ethylene
gas was passed into a solution of 1c (14.0 mg, 0.014 mmol) in
CH2Cl2 (1 mL) for 5 min at -20 °C. The pale yellow solution
was warmed to room temperature and stirred for 7.5 h. GLC
3
2

5638 Organometallics, Vol. 17, No. 26, 1998
Ozawa and Kamite
Ta ble 4. Cr ysta l Da ta a n d Deta ils of th e Str u ctu r e Deter m in a tion for 1a , 1c, a n d 2e
1a
32H44P2Si2Pt
1c
2e
formula
fw
C
C52H52P2Si2Pt
990.19
C54H54P2Si2Pt
1016.23
741.91
cryst size, mm
cryst system
space group
0.4 × 0.4 × 0.3
monoclinic
C2/c (No. 15)
0.15 × 0.1 × 0.1
0.45 × 0.4 × 0.3
monoclinic
triclinic
P21/n (No. 14)
P1 (No. 2)
14.124(8)
14.899(8)
12.351(2)
100.29(3)
106.99(3)
100.55(4)
2367(2)
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
17.546(2)
11.398(4)
17.643(5)
11.477(4)
19.06(1)
20.943(4)
110.24(2)
96.59(2)
3310(1)
4
1.488
44.09
4.0-55.0
ω-2θ
1.31 + 0.30 tan θ
16, fixed
293
4550(2)
4
1.445
32.28
4.0-54.9
ω-2θ
1.41 + 0.35 tan θ
16, fixed
293
2
d
calcd, g cm-3
1.425
31.04
4.0-45.0
ω-2θ
1.15 + 0.30 tan θ
8, fixed
293
µ(Mo KR), cm-1
2θ range, deg
scan type
∆ω, deg
scan speed, deg min-1
temp, K
linear decay, %
abs corr
4.93
2.66
7.33
empirical
0.717, 1.00
4118
3985 (Rint ) 0.018)
3356 (I ) 3σ(I))
169
empirical
0.839, 1.00
8522
8285 (Rint ) 0.057)
4538 (I ) 2σ(I))
515
empirical
0.588, 1.00
6487
6183 (Rint ) 0.050)
5366 (I ) 3σ(I))
533
min and max trans factors
no. of reflcns collcd
no. of unique reflcns
no. of observed reflections
no. of variables
R
0.026
0.042
0.031
Rw
0.035
0.058
0.041
goodness of fit
max ∆/σ in final cycle
max and min peak, e Å-3
1.12
0.00
0.96
0.01
1.10
0.00
0.94, -0.99 (near Pt)
1.24, -1.05 (near Pt)
0.96, -1.20 (near Pt)
analysis of the resulting solution using MeSiPh3 as an internal
standard revealed the formation of CH2dCHSiPh3 in 93%
yield. The formation of vinylsilane was also confirmed by GC-
mass spectrometry.
thermal parameters for all non-hydrogen atoms. In the final
cycles of refinement, hydrogen atoms were located at idealized
positions (d(C-H) ) 0.95 Å) with isotropic temperature factors
(Biso ) 1.20Bbonded atom) and were included in the calculation
without refinement of their parameters. The function mini-
mized in least-squares was ∑w(|Fo| - |Fc|)2 (w ) 1/[σ2(Fo)]).
Crystal data and details of data collection and refinement are
summarized in Table 4. Additional information is available
as Supporting Information.
To a solution of 1c (103 mg, 0.104 mmol) in CH2Cl2 (2 mL)
was added 1-hexyne (38 µL, 0.33 mmol) by means of a syringe.
The solution was stirred at room temperature for 30 min. The
31P{1H} NMR spectrum exhibited two sets of doublets assign-
able to the insertion complex in 96% selectivity: δ -13.0 (d,
1
2
2J P-P ) 20 Hz, J Pt-P ) 1403 Hz), -20.8 (d, J P-P ) 20 Hz,
1J Pt-P ) 1606 Hz). Volatile materials were removed by pump-
ing, and the resulting oily material was washed with pentane
(3 mL × 3) at 0 °C and dried under vacuum (72 mg). 31P{1H}
NMR of the product exhibited many unidentified signals
together with the doublets arising from the insertion complex.
Further purification by recrystallization was unsuccessful.
X-r a y Diffr a ction Stu d ies. Single crystals for X-ray dif-
fraction study were grown by slow diffusion of a CH2Cl2
solution to Et2O at -20 °C. All measurements were performed
on a Rigaku AFC7R (for 1a and 1c) or Rigaku AFC7 (for 2e)
four-circle diffractometer with graphite monochromated Mo
KR radiation (λ ) 0.710 69 Å). Unit cell dimensions were
obtained from a least-squares treatment of the setting angles
of automatically centered 25 reflections with θ > 25°. Diffrac-
tion data were collected at 20 °C using the ω-2θ scan
technique at a scan rate of 16° (for 1a and 1c) or 8° min-1 (for
2e) in ω. The data were corrected for Lorentz and polarization
effects, decay (based on three standard reflections monitored
at every 150 reflection measurements), and absorption (em-
pirical, based on azimuthal scans of three reflections).
The unit cell dimensions and systematic absences in the
diffractometer data of 1a (hkl, h + k * 2n; h0l, l * 2n)
suggested the space group Cc (No. 9) or C2/c (No. 15). The
structure was initially solved and refined in the higher
symmetrical space group C2/c, and the least-squares calcula-
tion successfully converged (maximum ∆/σ in the final cycle
) 0.00). A trial with alternative space group Cc did not
converge sufficiently (maximum ∆/σ in the final cycle ) 1.43).
The space group P21/n (No. 14) for 1c was uniquely determined
(h0l, h + l * 2n; 0k0, k * 2n). The space group for 2e (P1h (No.
2)) was based on the unit cell dimensions and statistical
analysis of the intensity distribution. The refinement con-
verged sufficiently (maximum ∆/σ in the final cycle ) 0.00),
and thereby the other possibility (P1) was not examined.
Kin etic Stu d ies. A typical procedure is as follows. cis-Pt-
(SiMePh2)(PMe2Ph)2 (1b) (13.0 mg, 15.0 µmol) was placed in
an NMR sample tube equipped with a rubber septum cap and
the system was replaced with nitrogen gas at room tempera-
ture. Phenylacetylene (32.8 µL, 0.300 mmol) was added, and
a 10 mM solution of 4,4′-dimethylbiphenyl in CD2Cl2 was
added at -50 °C to adjust the total volume of the solution to
be 0.6 mL. The sample was placed in an NMR sample probe
controlled to -5.0 ( 0.1 °C and examined by 1H NMR
spectroscopy. The time course of the insertion was followed
by measuring the relative peak integration of the methyl signal
of 4,4′-dimethylbiphenyl (δ 2.38) and the SiCH3 signal of the
product 2b (δ 1.48) at intervals. All kinetic studies were
similarly conducted. The reaction of 1a was followed by 31P{1H}
NMR spectroscopy.
All calculations were performed with the TEXSAN Crystal
Structure Analysis Package provided by Rigaku Corp. The
scattering factors were taken from ref 23. The structures were
solved by heavy atom Patterson methods (PATTY) and ex-
panded using Fourier techniques (DIRDIF94). Each structure
was refined by full-matrix least-squares with anisotropic
(23) Cromer, D. T.; Waber, J . T. International Tables for X-ray
Crystallography; The Kynoch Press: Birmingham, U.K., 1974; Vol. IV.

Phenylacetylene Insertion into (SiR3)2-Pt Complexes
Organometallics, Vol. 17, No. 26, 1998 5639
P r ep a r a tion a n d Rea ction of cis-P t(SiMe2P h )(SiP h 3)-
(P Me2P h )2 (1f). Complex 1c (150 mg, 0.151 mmol) was placed
in a 25 mL Schlenk tube and dissolved in benzene (8 mL).
HSiMe2Ph (20.6 mg, 0.151 mmol) was added. The solution was
stirred at room temperature for 10 min and then concentrated
to dryness by pumping. The resulting yellow solid was washed
with hexane (3 mL × 3) and dissolved in CH2Cl2 (ca. 1 mL).
Et2O (ca. 3 mL) was layered, and the solvent layers were
allowed to stand at room temperature for 12 h and then at
-20 °C for 1 day to give yellow crystals (79 mg). The 31P{1H}
NMR spectrum (CD2Cl2, -50 °C) indicated the presence of 1f
and 1c in a 97:3 ratio. Several attempts to obtain pure 1f were
unsuccessful.
and P-C couplings in the signals arising from the methyl
protons and carbons of SiMe2Ph group.
Compound 2f. 1H NMR (CD2Cl2, -20 °C): δ 0.41 (s, 1H,
2
3
SiCH3), 0.65 (d, J P-H ) 8.4 Hz, J Pt-H ) 19.2 Hz, 3H, PCH3),
2
0.88 (s, 3H, SiCH3), 1.03 (d, J P-H ) 8.1 Hz, 3H, PCH3), 1.05
2
2
(d, J P-H ) 8.1 Hz, 3H, PCH3), 1.11 (d, J P-H ) 8.1 Hz, 3H,
PCH3), 6.86 (t, 2H, Ph), 6.95-7.60 (m, 34H, Ph, PtCdCH). 13C-
{1H} NMR (CD2Cl2, -20 °C): δ 0.3 (s, SiCH3), 0.5 (s, SiCH3),
1
2
1
13.0 (d, J P-C ) 24 Hz, J Pt-C ) 18 Hz, PCH3), 14.4 (dd, J P-C
) 29 Hz, J P-C ) 3 Hz, PCH3), 15.5 (dd, J P-C ) 31 Hz, J P-C
3
1
3
1
3
) 4 Hz, PCH3), 17.1 (dd, J P-C ) 31 Hz, J P-C ) 4 Hz, PCH3),
125.4 (s, PtCdCH), 126.2 (s, Ph), 126.5 (s, Ph), 126.9 (s, Ph),
127.6 (s, Ph), 128.1 (s, Ph), 128.2 (d, 3J P-C ) 7 Hz, PPh), 128.4
1
3
3
3
Compound 1f. H NMR (CD2Cl2): δ -0.06 (s, J Pt-H ) 24.9
Hz, 6H, SiCH3), 0.60 (d, 2J P-H ) 7.8 Hz, 3J Pt-H ) 16.6 Hz, 12H,
PCH3), 7.25-7.44 (m, 22H, Ph), 7.66 (dd, 2H, Ph), 7.99 (dd,
(d, J P-C ) 9 Hz, PPh), 129.2 (s, J Pt-C ) 44 Hz, PtC(Ph)d
2
CH), 129.9 (s, Ph), 130.4 (d, J P-C ) 10 Hz, PPh), 131.0 (d,
2J P-C ) 11 Hz, PPh), 133.9 (s, Ph), 137.1-138.5 (m, Ph), 144.2
2
6H, Ph). 13C{1H} NMR (CD2Cl2): δ 5.7 (s, J Pt-C ) 71 Hz,
3
2
(s, PtCdCSiPh), 144.6 (d, J P-C ) 8 Hz, J Pt-C ) 53 Hz,
1
2
PtSiPh), 152.5 (d, 3J P-C ) 5 Hz, 2J Pt-C ) 33 Hz, PtC(Ph)dCH),
SiCH3), 15.7 (d, J P-C ) 25 Hz, J Pt-C ) 20 Hz, PCH3), 126.9
2
1
(s, SiPh), 127.2 (s, SiPh), 127.3 (s, SiPh), 127.5 (s, SiPh), 128.4
178.5 (dd, J P-C ) 97 and 14 Hz, J Pt-C ) 756 Hz, PtCdCH).
3
31P{1H} NMR (CD2Cl2, -20 °C): δ -14.5 (d, J P-P ) 19 Hz,
2
(d, J P-C ) 8 Hz, PPh), 129.5 (s, PPh), 130.5 (m, PPh), 134.6
(s, 3J Pt-C ) 15 Hz, SiPh), 137.6 (s, 3J Pt-C ) 22 Hz, SiPh), 140.8
1J Pt-P ) 1275 Hz, J Si-P ) 175 Hz), -13.2 (d, J P-P ) 20 Hz,
2
2
1
2
1J Pt-P ) 1803 Hz).
(d, J P-C ) 43 Hz, PPh), 145.8 (t, J Pt-C ) 53 Hz, SiPh), 152.5
(t, SiPh). 31P{1H} NMR (CD2Cl2, -50 °C): δ -6.3 (d, J P-P
)
2
1
2
2
23 Hz, J Pt-P ) 1679 Hz, J Si-P ) 160 Hz), -9.1 (d, J P-P ) 25
Hz, J Pt-P ) 1453 Hz, J Si-P ) 146 Hz).
Ack n ow led gm en t. We are indebted to Prof. S.
Sakaki (Kumamoto University) for helpful discussions
and comments. This work was supported by a Grant-
in-Aid for Scientific Research on Priority Area “The
Chemistry of Inter-element Linkage” (Grant No.
09239105) from the Ministry of Education, Science,
Sports and Culture, J apan.
1
2
The mixture of 1f and 1c thus prepared (18.8 mg, 21.7 µmol)
was placed in an NMR sample tube equipped with a rubber
septum cap and dissolved in CD2Cl2 (0.6 mL) at room tem-
perature. Phenylacetylene (23.8 µL, 0.217 mmol) was added,
and the solution was examined by 31P{1H} NMR spectroscopy
at 0 °C, showing the formation of four kinds of products (A-
2
D) in a 90:4:3:3 ratio: A (δ -14.5 (d), -17.5 (d); J P-P ) 19
Hz), B (δ -12.6 (d), -17.0 (d); 2J P-P ) 21 Hz), C (δ -13.5 (d),
Su p p or tin g In for m a tion Ava ila ble: Details of the struc-
ture determination of 1a , 1c, and 2e including figures giving
atomic numbering schemes and tables of atomic coordinates,
thermal parameters, and full bond distances and angles (23
pages). Ordering information is given on any current masthead
page.
2
2
-17.0 (d); J P-P ) 20 Hz), D (δ -14.4 (d), -17.9 (d); J P-P
)
20 Hz). Product D was assigned to 2c by comparison of the
NMR data with those of the authentic sample. On the other
hand, product A was identified as cis-Pt{C(Ph)dCH(SiMe2-
Ph)}(SiPh3)(PMe2Ph)2 (2f) on the basis of the following NMR
data. The characteristic features for the insertion of phenyl-
acetylene into the Pt-SiMe2Ph bond are the absence of P-H
OM980610W