Exclusive C-Si bond formation upon reaction of a platinum(II) alkyl with silanes

Article abstract of DOI:10.1021/om9802818

An unusual, highly selective C-Si coupling reaction takes place upon treating the platinum(II) alkyl complex cis-(DIPPIDH)(DIPPID)PtMe (2) (DIPPIDH = α²-(diisopropyl-phosphino)isodurene, 1) with HSiR₃ (R₃ = Et₃, EtMe₂, Me₂Ph), leading to formation of MeSiR₃ and the hydrido complex trans-(DIPPIDH)(DIPPID)PtH (5). The overall process involves activation of a Si-H bond, reverse-cyclometalation of the phosphine ligand DIPPIDH (1), and C-Si elimination. The resulting thermally stable platinum(II) hydride complex 5 was independently prepared by thermolysis of a platinum(II) dihydride, trans-(DIPPIDH)₂PtH₂ (6), which was obtained by reaction of 2 with H₂. In the absence of silane, the cis complex 2 isomerizes thermally to trans-(DIPPIDH)(DIPPID)PtMe (3), which does not react productively with silanes. Our results indicate that opening of the metallacycle of 2 by benzylic C-H formation is kinetically preferred over formation of CH₄ or CH₃SiR₃.

Full text of DOI:10.1021/om9802818

Organometallics 1998, 17, 4263-4266
4263
Exclu sive C-Si Bon d F or m a tion u p on Rea ction of a
P la tin u m (II) Alk yl w ith Sila n es
Milko E. van der Boom, J u¨rgen Ott, and David Milstein*
Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
Received April 13, 1998
An unusual, highly selective C-Si coupling reaction takes place upon treating the
platinum(II) alkyl complex cis-(DIPPIDH)(DIPPID)PtMe (2) (DIPPIDH ) R2-(diisopropyl-
phosphino)isodurene, 1) with HSiR3 (R3 ) Et3, EtMe2, Me2Ph), leading to formation of MeSiR3
and the hydrido complex trans-(DIPPIDH)(DIPPID)PtH (5). The overall process involves
activation of a Si-H bond, reverse-cyclometalation of the phosphine ligand DIPPIDH (1),
and C-Si elimination. The resulting thermally stable platinum(II) hydride complex 5 was
independently prepared by thermolysis of a platinum(II) dihydride, trans-(DIPPIDH)2PtH2
(6), which was obtained by reaction of 2 with H2. In the absence of silane, the cis complex
2 isomerizes thermally to trans-(DIPPIDH)(DIPPID)PtMe (3), which does not react
productively with silanes. Our results indicate that opening of the metallacycle of 2 by
benzylic C-H formation is kinetically preferred over formation of CH4 or CH3SiR3.
In tr od u ction
C-Si reductive elimination from cis-Pt(Me)(SiPh3)-
(PMePh2)2,8b,c and a reversible C-Si addition to Pt and
to binuclear Ru complexes was observed recently.8d,e We
demonstrated that C-H and C-Si reductive elimination
from isolated Ir(III) complexes can occur competitively
at comparable rates (Scheme 1).6
Hydrosilylation processes of olefins and acetylenes,1
which are frequently catalyzed by Pt complexes,2 are
thought to proceed by the Chalk-Harrod mechanism
which invokes C-Si bond formation as the product-
forming step.3 Reactions of metal alkyl complexes with
primary silanes can lead to products of both C-H and
C-Si reductive elimination.4,5,6 For instance, reaction
of (dmpe)Pt(Me)(OTf) (dmpe ) Me2PCH2CH2PMe2) with
Et3SiH led to formation of CH4 and CH3SiEt3.5a Meth-
ane was formed in the reaction of MeRh(PMe3)4 with
HSiPh3,5b while, in the analogous reaction with HSiEt3,
both methane and CH3SiEt3 were formed. A theoretical
study showed that CH3-H reductive elimination from
Pt(II) is 26.8 kcal/mol more favorable than that of CH3-
SiH3.7
We report here that reaction of the cyclometalated cis-
Pt(II) alkyl complex 2 with H-SiR3 (R3 ) Et3, EtMe2,
Me2Ph), results in exclusive C-Si bond formation and
generation of the new Pt(II) hydride complex 5 (Scheme
2). Interestingly, the trans isomer 3 exhibits totally
different reactivity.
Resu lts a n d Discu ssion
We reported recently that reaction of (COD)Pt(CH3)2
(COD ) 1,5-cyclooctadiene) with R2-(diisopropylphos-
phino)isodurene (1) in C6H6 at room temperature re-
sulted in cyclometalation to form complex 2 and CH4
quantitatively.9 Thermolysis of 2 in C6H6 resulted in
the competitive formation of the trans isomer 3 and
complex 4 with liberation of CH4 (Scheme 2). Continu-
ous heating of complex 3 resulted also in the quantita-
tive formation of CH4 and 4, which was fully charac-
terized by X-ray analysis.
Few detailed studies on selective metal-mediated
C-Si formation have been reported.6,8 Gladysz et al.
observed this key step directly by thermolysis of Fe-
(CO)4(SiMe3)(Me).8a Kinetic data were obtained for
* To whom correspondence should be addressed. Fax: +972-8-
9344142. E-mail: comilst@wiccmail.weizmann.ac.il.
(1) (a) Collman, J . P.; Hegedus, L. S.; Norton, R. J .; Finke, R. G.
Principles and Applications of Organotransition Metal Complexes;
University Science Book: Mill Valley, CA, 1987. (b) Ojima, I. In The
Chemistry of Organic Silicon Compounds; Patai, S., Rappoport, Z.,
Eds.; Wiley: Chichester, U.K., 1989; p 1479. (c) Schubert, U. Adv.
Organomet. Chem. 1990, 30, 151. (d) Braunstein, P.; Knorr, M. J .
Organomet. Chem. 1995, 500, 21.
Reaction of the cis-Pt(II)CH3 complex 2 with 5 equiv
of various primary silanes in C6D6 at 100 °C (120 h in
a sealed vessel) quantitatively afforded the new trans-
(8) (a) Brinkman, K. C.; Blakeney, A. J .; Krone-Schmidt, W.;
Gladysz, J . A. Organometallics 1984, 3, 1325. (b) Ozawa, F.; Hikida,
T.; Hayashi, T. J . Am. Chem. Soc. 1994, 116, 2844. (c) Ozawa, F.;
Hikidi, T.; Haseba. K.; Mori, T. Organometallics 1998, 17, 1018. (d)
Hofmann, E.; Heiss, H.; Neiteler, P.; Mu¨ller, G.; Lachmann, J . Angew.
Chem., Int. Ed. Engl. 1990, 29, 880. (e) Lin, W.; Wilson, S. R.; Girolami,
G. S. Organometallics 1994, 13, 2309. (f) Tanaka, Y.; Yamashita, H.;
Shimada, S.; Tanaka, M. Organometallics 1997, 16, 3246. (g) Schubert,
U.; Kunz, E.; Knorr, M.; Mu¨ller, J . Chem. Ber. 1987, 120, 1079. (h)
Schubert, U.; Knorr, M.; Straâer, C. J . Organomet. Chem. 1991, 411,
75.
(2) Speier, J . L. Adv. Organomet. Chem. 1979, 17, 407. Lewis, N. J .
Am. Chem. Soc. 1986, 108, 7228.
(3) Chalk, A. J .; Harrod, J . F. J . Am. Chem. Soc. 1965, 87, 16.
(4) Schubert, U. Angew. Chem., Int. Ed. Engl. 1994, 33, 419.
(5) (a) Goikhman, R.; Aizenberg, M.; Shimon, L. J . W.; Milstein, D.
J . Am. Chem. Soc. 1996, 118, 10894. (b) Thorn, D. L.; Harlow, R. L.
Inorg. Chem. 1990, 29, 2017. (c) Gozin, M.; Aizenberg, M.; Liou, S.-Y.;
Weisman, A.; Ben-David, Y. Milstein, D. Nature 1994, 370, 42.
(6) (a) Aizenberg, M.; Milstein, M. Angew. Chem., Int. Ed. Engl.
1994, 33, 317. (b) Aizenberg, M.; Milstein, D. J . Am. Chem. Soc. 1995,
117, 6456.
(9) Van der Boom, M. E.; Liou, S.-Y.; Shimon, L. J . W.; Ben-David,
Y.; Milstein, D. Organometallics 1996, 15, 2562.
(7) Sakaki, S.; Ieki, M. J . Am. Chem. Soc. 1993, 115, 2373.
S0276-7333(98)00281-7 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 08/22/1998

4264 Organometallics, Vol. 17, No. 19, 1998
van der Boom et al.
Sch em e 1
C-H and C-Si reductive elimination from Ir(III) com-
plexes are strongly influenced by the electronic proper-
ties of the substituents on silicon (Scheme 1),5a,b,6 no
such an influence was observed here.
Interestingly, it is possible to reverse the cyclometa-
lation of 2 by the use of mild H2 pressure. Treating
complex 2 with H2 (30 psi) in C6H6 at 60 °C (72 h in a
Fischer-Porter pressure vessel) resulted in quantitative
formation of the new trans-dihydride complex 6 and CH4
(Scheme 2). This complex, which was isolated and fully
characterized by 1H, 1H{31P}, 31P{1H}, and 31P-1H
HQMC NMR, IR, FD-MS, and elemental analysis,
exhibits spectroscopic features similar to those of analo-
gous Pt(II) trans-dihydride complexes.13 No other com-
plexes were detected. In the 31P{1H} one sharp singlet
appears at δ 53.7 ppm flanked by 195Pt satellites (1J PtP
) 2882.2 Hz), indicating that both phosphorus atoms
are magnetically equivalent. The hydride ligands ap-
pear in the 1H NMR as a characteristic triplet resonance
at δ -3.15 ppm (cis J PH ) 17.5 Hz; J PtH ) 796.0 Hz),
which collapses into a singlet upon 31P{1H} decoupling.
The IR spectrum shows a strong Pt-H band at ν ) 1744
cm-1, which is in the region usually observed for ν(Pt-
H) of trans-dihydrides (1710-1820 cm-1).13 Formation
of 1 equiv of CH4 was determined by quantitative GC
analysis of the gas phase. Thermolysis of 6 in C6D6 at
100 °C (120 h in a sealed vessel) resulted in selective
formation of complex 5 and presumably H2 (Scheme 2).
Formation of complex 4 was not observed, in contrast
to thermolysis of complexes 2 and 3, which results in
quantitative formation of complex 4 and CH4.9 Presum-
ably, the σ-bonded Pt-CH3 group promotes C-H acti-
vation. Complex 5 is considerably more stable than
complex 2 and was recovered unchanged when treated
with H2 (15 psi) in C6H6 at 80 °C for 24 h. The fact
that 5 was not detected in the reaction of 2 and H2
suggests that benzylic C-H reductive elimination is
kinetically preferred over CH4 formation.
Pt(II)H complex 5 and CH3SiR3 (R3 ) Et3, EtMe2, Me2-
Ph) as judged by 31P{1H}, H, H{31P}, H-1H COSY
NMR, IR, FD-MS, and GC-MS analysis of the product
solution and by comparison with authentic samples
(vide infra). Surprisingly, only traces of CH4 (<4%)
were detected by quantitative GC analysis of the gas
phase. When deuterated solvents were used, no deu-
terium incorporation into the products was observed.10
The 31P{1H} NMR spectrum of 5 exhibits two sharp
doublets of equal intensity at δ 89.2 and 45.1 ppm,
flanked by 195Pt satellites. The large 31P-31P coupling
(2J PP ) 392.8 Hz) shows that both nuclei are mutually
trans, in agreement with the observed 195Pt-31P cou-
pling constants (1J PtP ) 3193.5 and 2992.1 Hz, respec-
tively). The low-field shift of δ 89.2 reflects a deshield-
ing effect of this phosphorus atom due to the six-
membered ring.9,11 The signal at δ 45.1 is in a range
normally observed for (η1-phosphine)platinum(II) com-
plexes.9 The Pt-H ligand appears in the IR at ν ) 1964
1
1
1
2
1
1
cm-1 and in the H NMR as a virtual triplet at δ -7.00
2
(cis J PH ) 18.4 Hz, flanked by 195Pt satellites (1J PtH
)
773.2 Hz). These values are typical for a hydride trans
to a σ-bonded alkyl.12 FD-MS analysis shows the
molecular ion (M+, m/e 695) and an expected logical
isotope pattern.
By contrast, heating of the thermally more stable
trans-Pt(II)CH3 complex 3 with 5 equiv of HSiR3 (R3 )
Et3, Me2Ph) in C6D6 at 100 °C (120 h in a sealed vessel)
resulted in quantitave formation of complex 4 and CH4.
Surprisingly, formation of 5 and CH3SiR3 was not
observed by NMR, IR, and GC-MS analysis of the
product solution. Complex 5 is stable under the reaction
conditions and would have been easily detected spec-
troscopically had it been formed. Thus, as opposed to
the reactivity of the cis isomer 2, in the case of the trans
isomer 3 formation of complex 4 and CH4 is kinetically
(and probably thermodynamically) preferred over C-Si
bond generation. Significantly, complex 4 is thermally
stable under the reaction conditions and was recovered
unchanged even after heating with 5 equiv of HSiMe2-
Ph in C6H6 at 150 °C for 48 h. Thus, it cannot be an
intermediate in the formation of complex 5. These
experiments indicate that for the selective C-Si bond
formation the cis geometry of the metal complex is
required.
While the reason for the surprising, exclusive C-Si
bond formation is uncertain, we suggest that the fol-
lowing speculative mechanism can account for the
observations. Complex 2 can undergo phosphine dis-
sociation, promoted by the strong trans influence of the
σ benzyl ligand and the steric hindrance of the cyclo-
metalated ligand.14 H-Si or H-H oxidative addition
may afford a Pt(IV) species such as A (Scheme 3).15,16
The silyl or hydride ligands can labilize the benzyl group
(ArCH2-Pt) trans to it. The strong trans influence of
silyl ligands is similar or even higher than that of
(13) (a) Packett, D. L.; Trogler, W. C. J . Am. Chem. Soc. 1986, 108,
5036. (b) Yoshida, T.; Otsuka, S. J . Am. Chem. Soc. 1977, 99, 2134. (c)
Clark, H. C.; Goel, A. B.; Ogino, W. O. J . Organomet. Chem. 1978,
157, C16. (d) Immirzi, A.; Musco, A.; Garturan, G.; Belluco, U. Inorg.
Chim. Acta 1975, 12, L23. (e) Shaw, B. L.; Uttley, M. F. J . Chem. Soc.,
Chem. Commun. 1974, 918. (f) Goel, A. B.; Goel, S. Inorg. Chim. Acta
1982, 65, L77, 78. (g) Gerlach, D. H.; Kane, A. R.; Parshall, G. W.;
J esson, J . P.; Muetterties, E. L. J . Am. Chem. Soc. 1971, 93, 3543. (h)
Fornies, J .; Green, M.; Spencer, J . L.; Stone, F. G. A. J . Chem. Soc.,
Dalton Trans. 1977, 1006.
(14) Bubbling CO through a benzene solution of 2 at room temper-
ature for 1 h results in displacement of the η1-phosphine: Van der
Boom, M. E.; Milstein, D. Unpublished results.
(15) An analogous Pt species with R′ ) CH3 was postulated to be
an intermediate in the selective formation of complex 2 and CH4
(Scheme 2).9.
While reactions of various silanes with (dmpe)Pt(Me)-
(OTf) and with MeRh(PMe3)4 as well as the competitive
(10) Formation of 5, 6, CH3SiR3, and disiloxanes was observed at
55 °C. Reaction of 2 with 5 equiv of HSiPh3 in C6D6 at 55 °C (24 h in
a sealed vessel) resulted also in the formation of 5, 6, CH3SiPh3, and
Ph3SiOSiPh3. Only traces of CH4 (<4%) were detected. The formation
of 6 and disiloxanes could be suppressed using silanized glassware,
suggesting that adventitious water is involved in this process.
(11) Pregosin, P. S. In Phosphorus-31 NMR-Spectroscopy in Stere-
ochemical Analysis; Verkade, J . G., Quin, L. D., Eds.; VCH: Deerfield
Beach, FL, 1987.
(16) As pointed out by a reviewer, direct H-Si oxidative addition
to give a hexacoordinate Pt(IV) species, followed by a selective C-Si
reductive elimination, cannot be excluded.
(12) Moulton, C. J .; Shaw, B. L. J . Chem. Soc., Dalton Trans. 1976,
1020.

Exclusive C-Si Bond Formation
Organometallics, Vol. 17, No. 19, 1998 4265
Sch em e 2
Sch em e 3
Pt(Me)(SiPh3)(PMePh2)2 is a facile process and proceeds
by dissociation of a phosphine.8b,c Selective C-H reduc-
tive elimination from PtMe2(H)(bis(2-pyridylmethyl)-
amine)Cl was recently observed by Puddephat et al.19a
Complex C can undergo cyclometalation to yield 5 or
may be trapped by H2 to give 6,10,13 thermolysis of which
gives 5. Activation of benzylic C-H bonds by Pt(0) and
Pt(II) complexes was reported.9,22 While intermediacy
of an isomer of A in which the silane is in the apical
position and the hydride in the basal one is also possible,
it seems less likely on steric grounds.23
1
Con clu sion s
Addition of H-SiR3 (R3 ) Et3, EtMe2, Me2Ph) to the
Pt(II) alkyl complex 2 results in kinetically preferred
exclusive alkyl-SiR3 bond formation to yield complex
5. Interestingly, the cis geometry and the presence of
the metallacycle, which readily opens up, play a key role
in the selective product formation. The overall process
involves a series of reactions that are influenced by
electronic and steric factors. The C-Si coupling is
probably directed by the strong trans influence of the
ligands, while formation of the trans-Pt(II)H com-
plex 5 is sterically influenced by the bulky phosphine
ligand 1.
hydride ligands.6,17 Thus, ArCH2-H formation might
be preferred over that of CH4 or CH3SiR3 elimination.18
Since both C-H and C-Si reductive elimination pro-
cesses are possible,4-6,19,20 it can be suggested that the
overall process is kinetically controlled by electronic
factors in the (unobserved) Pt(IV) intermediate A.
Consequently, CH3-R′ (R′ ) H, SiR3) elimination occurs
from B,15 to afford a Pt(0) species C.10,21 As is well
documented, cis-alkyl(hydrido)Pt(II) and Pt(IV) species
are very unstable toward C-H reductive elimination.19
cis-Alkyl(silyl)Pt(II) species are postulated intermedi-
ates in the hydrosilylation processes of olefins.1,2 Ozawa
et al. showed that C-Si reductive elimination from cis-
Exp er im en ta l Section
The procedures and spectroscopic analysis are similar to
those previously reported.9 All reactions were carried out
(17) (a) Zlota, A. A.; Frolow, F.; Milstein, D. J . Chem. Soc., Chem.
Commun. 1989, 1826. (b) Haszeldine, R. N.; Parish, R. V.; Setchfield,
J . H. J . Organomet. Chem. 1973, 57, 279.
(18) Recent examples of reverse-cyclometalation as the following.
(a) Pd: Beller, M.; Riermeier, T.-H.; Haber, S.; Kleiner, H.-J .; Her-
rmann, W. A. Chem. Ber. 1996, 129, 1259. (b) Pt: Thorn, D. L.
Organometallics 1998, 17, 348. (c) Ir: Aizenberg, M.; Milstein, D.
Organometallics 1996, 15, 3317.
(19) C-H reductive elimination from Pt(IV): (a) J enkins, H. A.; Yap,
G. P. A.; Puddephatt, R. J . Organometallics 1997, 16, 1946. (b) Hill,
G. S.; Rendina, L. M.; Puddephatt, R. J . Organometallics 1995, 14,
4966. (c) Stahl, S. S.; Labinger, J . A.; Bercaw, J . E. J . Am. Chem. Soc.
1996, 118, 5961. C-H reductive elimination from Pt(II): (d) Abis, L.;
Sen, A.; Halpern, J . J . Am. Chem. Soc. 1978, 100, 2915.
(21) Formation of C was observed upon reacting 2 equiv of 1 and 5
equiv of HSiMe2Ph with (COD)Pt(CH3)2 at room temperature. This
reaction is not selective since CH4 and SiMe3Ph were detected. The
31P{1H} NMR of the reaction mixture shows a broadened signal at δ
61.15 (1J PtP ) 4220 Hz; compare (iPr3P)2Pt, 1J PtP ) 4202 Hz (Mann, B.
E.; Musco, A. J . Chem. Soc., Dalton Trans. 1980, 776)). Thermolysis
results in quantitative formation of complex 5. Apparently, the
metallacycle of 2 plays a key role in the selective C-Si formation.
(22) Hackett, M.; Whitesides, G. M. J . Am. Chem. Soc. 1988, 110,
1449.
(23) Oxidative addition of silanes to Ir(I) has been found to proceed
with 98% stereoselectivity: J ohnson, C. E.; Eisenberg, R. J . Am. Chem.
Soc. 1985, 107, 6531.
(20) Levi, C. J .; Puddephatt, R. J . Organometallics 1995, 14, 5019.

4266 Organometallics, Vol. 17, No. 19, 1998
van der Boom et al.
under an inert atmosphere. Solvents were dried, distilled, and
degassed before use. Complexes 2-4 and (COD)Pt(CH3)2 were
prepared according to published procedures.9,24
F or m a tion of 5 fr om 6. A solution of 6 (14 mg, 0.02 mmol)
in C6D6 (1 mL) was transferred to a 5 mm screw cap NMR
tube. The sealed NMR tube was placed in an oil bath at 100
°C and monitored by 31P{1H} NMR at room temperature. After
5 days 6 was selectively converted to 5; removal of the solvent
in a vacuum afforded a white powder. Performing the ther-
molysis of 6 in the presence of a 5-fold excess of HSiMe2Ph
resulted also in the selective formation of complex 5; no
influence of the silane on the progress and the product
formation was observed by 31P{1H} NMR. FD-MS (m/z): 695
(calcd M+, 695; correct isotope pattern). Anal. Calcd for
Rea ction of Com p lex 2 w ith HSiR3 (R3 ) Et3, Me2Et,
Me2P h ) a t 100 °C.10 A colorless solution of complex 2 (36 mg,
0.050 mmol) and a 5-fold excess of HSiR3 in C6D6 (1.5 mL)
was heated using a pressure flask at 100 °C for 5 days.
Quantitative analysis of the gas phase by GC showed only
traces of CH4 (<4%). The product solution was analyzed by
1
1H, H{31P}, 31P{1H} NMR, IR, GC-MS, and FD-MS showing
the quantitative formation of complex 5 (vide infra) and
MeSiR3. 1H NMR and GC-MS analysis showed traces of Et4-
Si, HSiMe3, Me2SiPh2, Me3SiPh, and disiloxanes; formation
of the latter could be suppressed using silanized glassware.
C
32H53P2Pt: C, 55.32; H 7.69. Found: C, 55.21; H, 7.41. 1H
NMR (400.19 MHz; C6D6): δ -7.00 (br t, 2J PH ) 18.4 Hz, 2J PH
2
3
) 773.2 Hz, 1 H, PtH), 0.86 (dd, J PH ) 14.2 Hz, J PH ) 7.0
Hz, 6 H, PCH(CH3)2), 1.00-1.10 (m, 12 H, PCH(CH3)2), 1.15
(dd, 2J PH ) 13.9 Hz, 3J HH ) 7.0 Hz, 6 H, PCH(CH3)2), 1.66 (m,
1 H, PCH(CH3)2), 1.85 (m, 3 H, PCH(CH3)2), 2.13 (s, 3 H,
ArCH3), 2.18 (s, 3 H, ArCH3), 2.30 (s, 6 H, o-ArCH3), 2.44 (m,
partly overlapped, 2 H, ArCH2Pt), 2.46 (s, 3 H, ArCH3), 2.84
F or m a tion of th e tr a n s-Dih yd r id e 6. A colorless solution
of 2 (43 mg, 0.06 mmol) in benzene (10 mL) was loaded in a
Fischer-Porter and pressurized with 30 psi of H2. The
yellowish solution was stirred at 60 °C for 3 days. Quantita-
tive analysis of the gas phase by GC showed formation of 1
equiv of CH4. Subsequently, the solvent was removed in a
vacuum and the resulting brownish solid was recrystallized
from pentane to afford complex 6 (33 mg, 80%) as a colorless
crystalline powder. FD-MS (m/z): 697 (calcd M+, 697; correct
isotope pattern). Anal. Calcd for C32H55P2Pt: C, 55.24; H 7.82.
Found: C, 54.94; H, 7.42. 1H NMR (400.19 MHz; C6D6): δ
3
2
(m, J PtH ) 37.3 Hz, 2 H, ArCH2P), 3.26 (dd, J PH ) 3.2 Hz,
3J PtH ) 10.2 Hz, 2 H, ArCH2P), 6.70-6.80 (m, 4 H, ArH). 31P-
{1H} NMR (161.9 MHz; C6D6): δ 45.1 (d, 2J PP ) 392.8 Hz, 1J PPt
) 2992.1 Hz, 1 P), 89.2 (d, 2J PP ) 392.8 Hz, 1J PtP ) 3193.5 Hz,
1 P). IR (film): ν(Pt-H) ) 1964 cm-1
.
Ack n ow led gm en t. This work was supported by the
Israel Science Foundation, J erusalem, Israel, and by the
MINERVA foundation, Munich, Germany. J .O. thanks
the DAAD foundation for a fellowship. D.M. is the
holder of the Israel Matz Professorial Chair in Organic
Chemistry. We thank R. Fokkens (University of Am-
sterdam, Amsterdam, The Netherlands) for performing
the FD-MS experiments.
2
1
-3.15 (t, J PH ) 17.5 Hz, J PtH ) 796 Hz, 2 H, PtH), 1.05 (q,
3J HH ) 7.5 Hz, 12 H, PCH(CH3)2), 1.20 (vq, J HH ) 7.4 Hz, 12
3
H, PCH(CH3)2), 1.95 (m, 4 H, PCH(CH3)2), 2.14 (s, 6 H,
p-ArCH3), 2.48 (s, 12 H, o-ArCH3), 3.31 (vt, 2J PH ) 3.4 Hz, 3J PtH
) 36.2 Hz, 4 H, PCH2Ar), 6.79 (s, 4 H, ArH). 31P{1H} NMR
1
(161.9 MHz; C6D6): δ 53.7 (s, J PtP ) 2882.2 Hz). IR (film):
ν(Pt-H) ) 1744 cm-1
.
(24) Clark, H. C.; Manzer, L. E. J . Organomet. Chem. 1973, 59, 411.
OM9802818