3248 Organometallics, Vol. 18, No. 16, 1999
Notes
Ph-Ct), 130.00 (s, 2 C, Ph-C4), 133.41 (d, J PC ) 12.10 Hz, 4 C,
Si(OMe)4 in the reaction of 1 with HSi(OMe)3 is probably
a consequence of the presence of the hemilabile ligand
at platinum. It should be pointed out, however, that Si-
(OMe)4 is not formed by decomposition of the bis(silyl)
complex 3, because the latter is stable after completion
of the reaction. As a consequence, Si(OMe)4 is probably
formed from one of the presumed Pt(IV) intermediates.
The routes leading to the small amounts of the two
disiloxanes are still debatable. We cannot completely
exclude that a portion of the Pt-Si bonds was oxidized
to Pt-O-Si bonds by small amounts of oxygen which
diffused into the reaction vessel. However, the observa-
tion that the composition of the reaction mixture does
not change significantly in the deliberate presence of
air contradicts this assumption. A more likely rational-
ization may therefore be the involvement of a competing
H3C-OSi oxidative addition. A few examples of oxida-
tive addition reactions of unstrained Calkyl-O bonds are
known in the literature, mainly for alkyl aryl ethers
(where the alkyl-O bond is added to the metal instead
of the aryl-O bond) or esters.
When the corresponding bisphosphine complex (dppe)-
Pt(CH3)2 (dppe ) Ph2PCH2CH2PPh2) was analogously
reacted under the same reaction conditions, no reaction
was observed within 60 h, and the starting compounds
were recovered in 95% yield. Thus, the reaction pre-
sented in this Communication shows that incorporation
of a P,N-chelating ligand strongly enhances the pro-
pensity of dialkylplatinum(II) complexes for alkyl/silyl
exchange by oxidative addition/reductive elimination
reactions compared to the corresponding bisphosphine
complexes. We attribute this to the activating effect of
the hemilabile P,N-chelating ligand. There is even
evidence for the addition of C-O bonds of alkoxysilyl
groups to the metal center and the promotion of reac-
tions involving silicon substituents. No products result-
ing from a Si-Si reductive elimination reaction were
observed under the conditions applied.
1
Ph-Ct), Ph-C1 not observed. H NMR (C6D6): δ ) 1.21 (d with
2
3
Pt satellites, J PtCH ) 66.53 Hz, J PPtCH ) 7.93 Hz, 3 H, trans-
PtCH3),20 1.48 (d with Pt satellites, J PtCH ) 90.34 Hz, J PPtCH
2
3
) 7.33 Hz, 3 H, cis-PtCH3),20 1.60-1.90 (m, 4 H, CH2CH2),
3
2.24 (s with Pt satellites, J PtNCH ) 18.01 Hz, 6 H, N(CH3)2),
6.90-7.10 (m, 6 H, Ph-H), 7.60-7.80 (m, 4 H, Ph-H). MS (70
eV): m/z ) 482 (M+, 1), 467 (M+ - CH3, 38), 452 (M+ - 2CH3,
100), 422 (M+ - 4CH3, 45), 405 (M+ - C6H5, 3), 345 (M+
4CH3 - C6H5, 10), 328 (M+ - 2C6H5, 5).
-
Rea ction of 1 w ith HSi(OMe)3. An amount of 0.1 mmol
(0.0482 g) of 1 was dissolved in 0.5 mL of argon-saturated
benzene-d6 (dried over CaH2) in an NMR tube equipped with
a PTFE liner at room temperature, followed by addition of 0.35
mmol (0.0427 g) of trimethoxysilane. All operations were
performed under an atmosphere of dry argon. Data for 2. 31P-
1
{1H} NMR: δ ) 48.66 (d with Pt and Si satellites, J PtP
)
2037.35 Hz, 2J SiPtP ) 12.2 Hz). 29Si NMR (INEPT): δ ) -43.66
(d with Pt satellites, 1J PtSi ) 2478.9 Hz, 2J PPtSi ) 12.2 Hz). 13C-
{1H} NMR: δ 4.62 (d, 2J PPtC ) 89.65 Hz, PtCH3), 32.10 (d, 1J PC
) 25.76 Hz, PCH2), 47.15 (s, N(CH3)2), 50.02 (s, Si(OCH3)3),
2
1
62.46 (d, J PCC ) 8.25 Hz, NCH2). H NMR: δ ) 0.87 (d with
Pt satellites, 2J PtCH ) 53.21 Hz, 3J PPtCH ) 7.45 Hz, 3 H, PtCH3),
1.85-2.09 (m, 4 H, 2 × -CH2-), 2.13 (s with Pt satellites,
3J PtNCH ) 12.30 Hz, 6 H, N(CH3)2), 3.71 (s, 9 H, O(CH3)3). Data
for 3. 31P{1H} NMR: δ ) 59.32 (d with Pt and Si satellites,
1J PtP ) 1424.56 Hz, 2J SiPtP ) 7.32 Hz, 2J SiPtP
) 268.6 Hz).
cis
trans
1
29Si NMR (INEPT): δ ) -44.94 (d with Pt satellites, J PtSi
)
2
2225.7 Hz, J PPtSi ) 7.32 Hz, cis-Si(OCH3)3), -3.41 (d with Pt
1
2
satellites, J PtSi ) 2308.0 Hz, J PPtSi ) 268.6 Hz, trans-Si-
(OCH3)3). 13C{1H} NMR: δ ) 33.29 (d, 1J PC ) 22.24 Hz, PCH2),
49.73 (s, N(CH3)2), 49.87 (s, trans-Si(OCH3)3), 50.16 (s, cis-Si-
(OCH3)3), 63.59 (d, J PCC ) 9.86 Hz, NCH2). 1H NMR: δ )
2
1.85-2.09 (m, 4 H, 2 × -CH2-), 2.79 (s with Pt satellites,
3J PtNCH ) 18.39 Hz, 6 H, N(CH3)2), 3.62 (s, 9 H, cis-Si(OCH3)3),
3.98 (s, 9 H, trans-Si(OCH3)3). The hydrogen and carbon atoms
of the phenyl groups could not be assigned due to overlapping
signals.
P r ep a r a tion of d -1. Reaction of (nbd)PtCl2 with 2.2 molar
equiv of CD3MgI (1 M solution in Et2O) according to ref 10 led
to formation of (nbd)Pt(CD3)2 in 89% yield. 13C{1H} NMR
1
(C6D6): δ ) 5.71 (sept, J DC ) 19.35 Hz, Pt(CD3)2, the Pt
satellites could not be observed), 49.80 (s with Pt satellites,
J PtC ) 39.23 Hz), 73.01 (s with Pt satellites, J PtC ) 44.14, 2
C), 87.81 (s with Pt satellites, J PtC ) 48.5 Hz, η-Calkene). 1H
NMR (C6D6): δ ) 0.95 (b, 2 H), 3.23 (b, 2 H), 4.54 (s with Pt
satellites, J PtH ) 39.78 Hz, 4 H, η-HCalkene). Reaction of (nbd)-
Pt(CD3)2 with Me2NCH2CH2PPh2 according to ref 12 resulted
in the isolation of [(κ2-P, N)-Me2NCH2CH2PPh2]Pt(CD3)2 in
85% yield. 31P{1H} NMR (C6D6): δ ) 36.17 (s with Pt satellites,
1J PtP ) 2060.54 Hz). 13C {1H} NMR (C6D6): δ ) -25.66 (sept,
1J DC ) 18.47 Hz, cis-CD3, no coupling to P and Pt could be
Exp er im en ta l Section
Syn th esis of 1. An amount of 1 mmol (0.323 g) of (nbd)-
Pt(CH3)2 was dissolved in 10 mL of dry, argon-saturated
6
benzene. After addition of 1 mmol (0.257 g) of 2-(dimeth-
ylphosphino)ethyldimethylamine11 and stirring for 2 h at room
temperature, the solvent was concentrated at reduced pressure
to about 2 mL. An amount of 30 mL of petroleum ether (30/
50) was added, and the reaction mixture was stored at -30
°C for 24 h to complete precipitation. The product was filtered,
washed with 2 × 5 mL of petroleum ether, and dried under
reduced pressure. Yield 84% (0.405 g) of 1 as a colorless solid.
Anal. Calcd for C18H26NPPt (482.46): C, 44.81; H, 5.43; N, 2.90.
Found: C, 45.03; H, 5.35; N, 2.81. 31P{1H} NMR (C6D6): δ )
1
2
observed), 3.34 (dsept, J DC ) 18.47 Hz, J PPtC ) 112.43 Hz,
trans-CD3, the Pt satellites could not be observed), 29.75 (d,
2
1J PC ) 26.1 Hz, PCH2), 49.52 (s, N(CH3)2), 64.84 (d, J PCC
)
2
9.23 Hz, NCH2), 128-135 (Ar-C). H NMR (C6H6:C6D6 ) 20:
1): δ ) 0.41 (d, J PPtCD ) 0.92 Hz, 3 D, CD3), 0.66 (d with Pt
satellites, J PtCD ) 14.08 Hz, J PPtCD ) 0.91 Hz, 3 D, CD3). H
NMR (C6D6): 1.5-1.7 (m, 2 H, CH2), 1.75-2.00 (m, 2 H, CH2),
2.26 (s with Pt satellites, J PtNCH ) 18.0 Hz, N(CH3)2), 6.90-
3
1
35.93 (s with Pt satellites, J PtP ) 2071.53 Hz). 13C{1H} NMR
2
3
1
1
(C6D6): δ ) -24.69 (d with Pt satellites, J PtC ) 748.74 Hz,
2J PPtC ) 4.21 Hz, 1 C, cis-PtCH3), 14.45 (d with Pt satellites,
1J PtC ) 709.80 Hz, 2J PPtC ) 113.48 Hz, 1 C, trans-PtCH3), 29.56
3
1
7.15 (m, 6 H, Ar-H), 7.5-7.7 (m, 4 H, Ar-H).
(d, J PC ) 25.78, 1 C, PCH2), 49.19 (s, 2 C, N(CH3)2), 64.44 (d,
2J PCC ) 9.47 Hz, 1 C, NCH2), 128.62 (d, J PC ) 9.47 Hz, 4 C,
Ack n ow led gm en t. Financial support by the Fonds
zur Fo¨rderung der wissenschaftlichen Forschung, Aus-
tria, is gratefully acknowledged. We also thank Wacker-
Chemie GmbH for gifts of chemicals.
Su p p or tin g In for m a tion Ava ila ble: NMR spectra of 1,
d-1, and taken from the reaction mixture after 20 h. This
material is available free of charge via the Internet at
http://pubs.acs.org.
(18) (a) Chang, L. S.; J ohnson, M. P.; Fink, M. Organometallics 1991,
10, 1219. (b) Pestana, D. C.; Koloski, T. S.; Berry, D. H. Organome-
tallics 1994, 13, 4173. (c) Figge, L. K.; Carroll, P. J .; Berry, D. H.
Organometallics 1996, 15, 209. (d) Yamashita, H.; Tanaka, M.; Goto,
M. Organometallics 1992, 11, 3227. (e) Curtis, M. D.; Epstein, P. S.
Adv. Organomet. Chem. 1981, 19, 213.
(19) Mitchell, G. P.; Tilley, T. D. Angew. Chem., Int. Ed. Engl. 1998,
39, 2524.
(20) The assignment of the PtCH3 protons was based on a CH-
COSY experiment.
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