Hydrodealkoxylation reactions of silyl ligands at platinum: reactivity of SiH3 and SiH2Me complexes

The platinum(II) complex [Pt(H)2(dcpe)] (1; dcpe = 1,2-bis(dicyclohexylphosphino)ethane) reacts with an excess of the dialkoxymethylsilanes (HSiMe(OR)2; R = Me, Et) to give the bis(silyl) complex [Pt(SiH2Me)2(dcpe)] (3) and trialkoxymethylsilanes by hydrodealkoxylation reactions. These rearrangements of the silyl ligands involve Si–O bond activations. The exchange of the alkoxy moieties against silicon-bound hydrogen atoms occurs stepwise. The intermediate complexes [Pt(H){SiMe(OEt)2}(dcpe)] (5), [Pt{SiMe(OEt)2}2(dcpe)] (6), [Pt{SiHMe(OEt)}2(dcpe)] (7) and [Pt{SiHMe(OMe)}2(dcpe)] (8) were detected. Treatment of the complex 1 with an excess of dichloromethylsilane yields the bis(silyl) complex [Pt(SiMeCl2)2(dcpe)] (9). The hydrido silyl complex [Pt(H)(SiMeCl2)(dcpe)] (10) was identified as an intermediate. The reactions of the complexes [Pt(SiH3)2(dcpe)] (2) and [Pt(SiH2Me)2(dcpe)] (3) with iodomethane lead to a transfer of the SiH3 and SiH2Me ligands. Methylsilane and dimethylsilane, respectively, as well as the platinum diiodo complex [Pt(I)2(dcpe)] (11) were identified as main products.