Structure and thermochemistry of β-silicon carbenium ions in the gas phase

Both protonation of trimethylvinylsilane and addition of Me3Si+ to ethylene in the gas phase produce the cation Me3Si(CH2CH2)+, with 39 kcal mol–1 stabilization energy relative to ethyl cation; however, chloride abstraction from Me3SiCHClCH3 yields a mixture of ions resulting from competing methyl and hydrogen shifts in the nascent silylcarbenium ion.