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首页> 外文期刊>Organometallics >Di- and Trinuclear Complexes of Pd(0) and Pt(0) with Bridging Silylene Ligands: Structures with a Coordinatively Unsaturated Metal Center and Their Reactions with Alkynes
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Di- and Trinuclear Complexes of Pd(0) and Pt(0) with Bridging Silylene Ligands: Structures with a Coordinatively Unsaturated Metal Center and Their Reactions with Alkynes

机译：Di- and Trinuclear Complexes of Pd(0) and Pt(0) with Bridging Silylene Ligands: Structures with a Coordinatively Unsaturated Metal Center and Their Reactions with Alkynes

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摘要

Reactions of Et2NSiPh2B(pin) with [Pd(PCy3)(2)] and [Pt(PCy3)(2)] produce dinuclear Pd(0) and Pt(0) complexes bearing a bridging diphenylsilylene ligand, [{M-1(PCy3)}-{M-2(PCy3)(2)}(mu-SiPh2)] (1-Pd-2, M-1 = M-2 = Pd; 1-PdPt, M-1 = Pd, M-2 = Pt; 1-Pt-2, M-1 = M-2 = Pt), and a trinuclear Pd complex, [{Pd(PCy3)}(3)(mu-SiPh2)(mu(3)-SiPh2)] (2), depending on the con-ditions used. X-ray crystallographic studies of 1-Pd2, 1-PdPt, and 1-Pt-2 show that the molecules contain an almost linear P-M-M- P arrangement with P-M-M angles in the range of 157-168 degrees. The distance between two metal centers decreased in the order of 1-Pd-2 > 1-PdPt > 1-Pt-2. Complex 2 is composed of a bent Pd-3 backbone with a Pd-Pd-Pd angle of 110 degrees. All Pd atoms are bridged by a SiPh2 ligand, while two of them are bridged by another SiPh2 ligand. Complex 1-Pd-2 catalyzes the 1:2 cycloaddition of Et2NSiPh2B(pin) with HCCPh to form 2,4-and 3,4-disubstituted siloles. A similar reaction with HC (CBu)-Bu-t afforded a mixture of the corresponding siloles and alkynyl(alkenyl)diphenylsilane, ((BuC)-Bu-t C)((BuCH)-Bu-t CH)SiPh2 (5c). The yields and selectivities of the products are lower than those obtained in the previously reported reactions catalyzed by the Pd-PPh3 catalytic system. The stoichiometric reactions of HC (CBu)-Bu-t and HC CSiMe3 with 1-Pt-2 trigger a C-H(sp) bond activation process to occur to form complexes with the alkynyl ligand, [{PtH(PCy3)}{Pt(PCy3)}(mu-SiPh2)(mu-eta(1),eta(2)-C CR)] (6b, R = Bu-t; 6c, R = SiMe3) at room temperature. Complex 6c reacts with alkynes at 70 degrees C to form complexes bearing the bridging alkenylsilyl ligand, [{Pt(PCy3)}(2){mu-eta(1),eta(2)-SiPh2C(SiMe3)=CH2}(mu-eta(1),eta(2)-C CR)] (7b, R = Bu-t; 7c, R = SiMe3). Complex 7c undergoes reductive elimination of alkynyl(alkenyl)diphenylsilane upon the addition of a diphosphine ligand. The reaction of dimethyl acetylenedicarboxylate with 1-Pt2 gives a diplatinum complex with a silaplatinacyclohexadiene structure, [{(Cy3P)(PCy3)}(mu-eta(1),eta(2)-CZ CZ)] (8, Z = CO2Me). The mechanisms of the stoichiometric and catalytic reactions are discussed based on our experimental results.

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