Silyl-substituted alkylidenes: preparation of the novel complexes and mechanistic studies of their formation from reactions of alkylidenes with silanes and silyl-to-alkylidyne migration

Alkylidene complexes (Me3SiCH2)(3)Ta(PMe3)=CHSiMe3 (1) and Me3SiCH2Ta(PMe3)(2)(=CHSiMe3)(2) (3a) were found to react with phenylsilanes H2SiR'Ph (R' = Me, Ph) and (PhSiH2)(2)CH2 to give disilyl-substituted alkylidenes (Me3SiCH2)(3) Ta=C(SiMe3)(SiHR'Ph) (2) and novel metallasilacyclobutadiene and metalladisilacyclohexadiene complexes. Silyl-substituted alkylidene complex ((BuCH2)-C-t)(2)W(=O)[=C(Bu-t)(SiPh2But)] (5a) was prepared from the reaction of O-2 with an equilibrium mixture ((BuCH2)-C-t)W(=CHBut)(2)(SiPh2But) (4b) <----> (Bu-t CH2)(2)W(dropCBu(t))(SiPh2But) (4a). Our recent studies of the preparation of these complexes and mechanistic pathways in the formation of these silyl-substituted alkylidene complexes are summarized. (C) 2002 Elsevier Science B.V. All rights reserved

Reactions of d(0) alkylidene and amide complexes with silanes

Reactions of silanes with d(o) Ta alkylidene and Group 4 amide complexes were found to involve the initial attack on silicon atoms in the silanes by nucleophilic alkylidene carbon or amide nitrogen atoms. The reaction of (Me3SiCH2)(3)Ta(PMe3)[=CHSiMe3] (1) with H2SiR'Ph (R' = Me, Ph) gave (Me3SiCH2)(3)Ta[=C(SiMe3)SiHR'Ph] (2a-b). Similar reactions of these two silanes and (H2PhSi)(2)CH2 with (Me3SiCH2)Ta(PMe3)(2)[=CHR](2) (R = SiMe3, 3; CMe3, 4) yielded novel metallasilacyclobutadienes and a metalladisilacyclohexadiene, respectively. In comparison, the reactions between M(NMe2)(4) (M = Ti, Zr, Hf) and silanes were found to give aminosilanes and metal amide hydride species which were perhaps involved in the formation of titanium-silicon-nitride (Ti-Si-N) ternary materials