γ-Ray- and UV-induced generation of methyl(phenyl)silylene and silene species from heptamethyl-2-phenyltrisilane

Abstract

A benzene solution of heptamethyl-2-phenyltrisilane (1) has been irradiated with γ-rays in the presence of methanol. Hexamethyldisilane, methoxymethyl(phenyl)silane (2) and a 1-methoxytetramethyldisilanyl- and trimethylsilyl-substituted cyclohexadiene (3) were produced. The formation of 2 and 3 can be interpreted in terms of reactions of methanol with methyl(phenyl)silylene and a silicon–carbon double-bonded intermediate (silene), respectively. These intermediates are generated as follows. Benzene is first excited by γ-rays and by collisions the energy transfers to 1. Excited 1 decomposes to give methyl(phenyl)silylene or undergoes rearrangement to a silene intermediate as when 1 is excited by UV light. A kinetic study revealed that the energy transfer in the γ-irradiated system is the same as that in a UV-irradiated system.