Vinylmetalloids. IV. Intramolecular bond-forming reaction of vinylsilanes upon electron impact

The behavior of a number of alpha-substituted vinylsilanes upon electron impact in the mass spectrometer is reported. All such compounds exhibit fragment ions which can be understood by a process involving prior loss of a radical fragment from the molecular ion followed by bond formation between the alpha-substituent and the silicon center with loss of the remaining portion of the vinyl moiety. Using the alpha-deuterated vinyltrimethylsilane, this process was shown to be an important one which had not been previously considered for such systems. MIKE ** data were also obtained on alpha bromovinyltrimethylsilane to add support for such a process.