Synthesis and Rearrangements of Tungsten Germyl Silyl Complexes

Abstract

Germyl silyl complexes Cp2W(SiMe3)(GeR3) have been synthesized by the reaction of the tungsten silene complex Cp2W(η2-Me2SiCH2) with germanes HGeR3 (GeR3 = GeMe3 (2), GeMe2H (3a), GetBu2H (3b), GePh2H (3c)). Chlorogermyl derivatives are synthesized by the reaction of 3a-c with CCl4 to yield Cp2W(SiMe3)(GeMe2Cl) (4a), Cp2W(SiMe3)(GetBu2Cl) (4b), and Cp2W(SiMe3)(GePh2Cl) (4c). Complex 4a has been structurally characterized by a single-crystal X-ray diffraction study. The corresponding triflate derivative, Cp2W(SiMe3)(GeMe2OTf) (5a), has been prepared by the reaction of 4a and trimethylsilyl triflate. Substitution of triflate for chloride in Cp2W(SiMe3)(GetBu2Cl) (4b) requires mild heating (80 °C) and is accompanied by concurrent redistribution of groups between silyl and germyl centers to yield the silyl triflate Cp2W(SiMe2OTf)(GetBu2Me) (6b). Under thermolytic conditions, germyl silyl complexes undergo intra- and intermolecular redistribution of substituents between the germyl and silyl ligands. This process is proposed to occur via a cationic germylene complex formed by triflate or chloride dissociation.