Mechanisms of pyrolysis and bond dissociation energies in trimethylsilane

Abstract

A non-chain mechanism is suggested for the pyrolysis of trimethylsilane in the gas phase at low pressure in a stirred-flow system between 943 and 1031 K. Arrhenius parameters for the unimolecular dissociations Me₃SiH → Me₂SiH + Me· and Me₃SiH → Me₃Si·+ H· are given respectively by log k₁/s^–1= 15·9 ± 0·7 – 320 ± 2/2·303 RT and log k₂/s^–1= 15·6 ± 0·7 – 336 ± 2/2·303RT(activation energies in kJ mol^–1). The stability of α-silylalkyl radicals is confirmed, and evidence is advanced for radical disproportionations leading ultimately to disilacyclobutanes.