METASTABLE ION STUDY OF ORGANOSILICON COMPOUNDS .7. LOSSES OF C2H4 AND CH4 FROM THE METASTABLE DIMETHYLSILYL ION [(CH3)2SI+H]

The spontaneous unimolecular dissociative reactions of dimethylsilyl c ations (CH3)2Si+H (1+; m/z59) have been investigated by mass-analyzed ion kinetic energy (MIKE) spectrometry and deuterium-labelling studies . Excepting the losses of H and H-2, the ions 1+ mainly eliminate C2H4 and CH4 to produce product ions at m/z 31 and 43, respectively. Almos t complete hydrogen scrambling occurs prior to the C2H4 loss, but only a small degree of scrambling occurs in the CH4 loss. Predominantly, t he hydrogen atom bound to Si participates in the latter reaction, cont rary to the previously reported mechanism.