Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes

Abstract

Abstract Treatment of a variety of alkyl- and arylsilanes, R4-nSi(C≡C-R′)n, and -germanes, R4-nGe(C≡C-R′)n (1-7), with equimolar quantities of the dialkylmetal hydrides HMR″ 2 (M = Al, Ga; R″ = CMe3, CH2CHMe2) yielded by reduction of a single alkynyl group a series of mixed alkenyl-alkynyl compounds R4-nSi(C≡C-R′)n-1{C(MR″2) =CHR′} (n = 2, 3) and R2Ge(C≡C-R′){C[M(CMe3)2]=CHR′} (8-13). Reactions with two equivalents of the hydrides afforded the dialkenyl compounds R2E{C[(M(CMe3)2]=CHR′}2 (E = Si, Ge, 14-17), Ge(C≡C- CMe3)2{C[Ga(CMe3)2]=CH-CMe3}2 (18) and MeSi(C≡C-p-Tol){C[Ga(CMe3)2]=CH-p-Tol}2 (19) [R = Ph, Mes, Me, C6F5; R′ = CMe3, Ph). Most of the products were characterised by Xray crystallography which for the alkenyl-alkynyl derivatives revealed short intramolecular contacts between the coordinatively unsaturated metal atoms and the a-C atoms of unreacted ethynyl groups Cα≡C-R′.