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

Abstract

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.