Preparation and properties of compounds containing platinum–silicon bonds

Three methods are described for the preparation of silylplatinous complexes, viz. (a) reaction of R31SiLi compounds with cis-[PtCl2(PR23)2] and [PtCl2(Ph2PCH2CH2PPh2)] to give cis-[Pt(SiR13)2(PR23)2](R13Si = MePh2Si, R23P = Me2PhP or R13Si = Me2PhSi, R23P = MePh2P) and [Pt(SiR13)2(Ph2PCH2CH2PPh2)](R13Si = MePh2Si), respectively; (b) reaction of trichlorosilane or triarylsilanes, R3SiH, with trans-[PtHCl(PMe2Ph)2] to give trans-[PtCl(SiR3)(PMe2Ph)2](R = Cl, C6F5, or XC6H4 where X = H, p-OMe, p-NMe2, m-CF3, p-CF3, m-F, p-F, p-Cl, p-Me); (c) reaction of triarylsilanes, R3SiH, with [PtX2(QMe2Ph)2] compounds, where X = Cl or Br and Q = P or As, in benzene–triethylamine to give trans-[PtX(SiR3)(QMe2Ph)2] derivatives (e.g., R3Si = MePh2Si or R = XC6H4, where X = H, p-OMe, p-NMe2, and m- or p-F, -Cl, -CF3, and -Me). Triphenylgermane behaves analogously in reactions (b) and (c), and triethylstannane in reaction (b).Features of the n.m.r. and i.r. spectra are discussed, and the very low values of ν(Pt–Cl) and ν(Pt–Br) in the trans-[PtX(SiR13)(PR23)2] compounds are ascribed to the large inductive trans-effect of silicon. The cleavages of the Pt–Si bonds in some of these compounds by halogen, hydrogen chloride, methyl iodide, thiophenol, and hydrogen are described.