Electron impact ionization of phenylsilane. Evidence for the formation of phenylsilyl and silacycloheptatrienyl cations

Since the original suggestion by Mayerson and co-workers that hydrogen atom loss from the molecular toluene cation results in the formation of the cycloheptatrienyl cation (Ia), a number of studies have attempted to elucidate the structure, energetics, and modes of formation of C_7H_7^+ isomers. It is now well understood that electron impact ionization of toluene yields both Ia and IIa. The relative yield of the two isomers is dependent on the internal energy content of the molecular toluene cation.