Mechanisms of pyrolysis and bond dissociation energies in trimethylsilane

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.