Heavy Analogs of Carbenes: Silylenes, Germylenes, Stannylenes and Plumbylenes

Abstract

The Si-Si bonds of the oligo-or polysilanes chains can be cleaved upon photolysis in two ways, forming either silylenes or silyl radicals. 2 Thus, photolysis of both poly(di-nbutylsilane) and poly(di-n-hexylsilane) with shorter wavelength light [248 nm (pulsed) or 254 nm (CW)] resulted in both extrusion of silylenes R 2 Si • • (R = n-butyl or n-hexyl) trapped with Et 3 SiH and homolytic Si-Si bond cleavage, whereas only polysilyl radicals were observed upon irradiation with longer wavelength light (λ > 300 nm). 3 Among the most frequently used precursors for the photochemical generation of silylenes are trisilanes RR Si(SiMe 3 ) 2 , which readily eliminate hexamethyldisilane Me 3 Si-SiMe 3 to form the corresponding silylenes RR Si • •. Thus, diphenylsilylene Ph 2 Si • • was produced by irradiation of Ph 2 Si(SiMe 3 ) 2 along with the by-products formed from the isomeric silatriene (Scheme 4.1). 4