Collision-Induced Dissociations of Negative-Ions Formed by Reaction of HO^- With Alkyl and Aryl Silanes. The Formation of Multiple Bonds to Silicon

Abstract

Collisional activation of alkyl and aryl siloxide ions produces a variety of ions and neutrals containing double bonds to silicon. Sila enolate ions and sila acyl ions RSi =O are common features of the spectra of alkylsiloxide ions; ab initio calculations suggest these ions to have considerable multiple bond character. It is proposed that most reactions proceed through ion complex intermediates. Specific proton transfer reactions often occur for ions Me₃SiCHR (R = C₃H₅, C₃H₃ or Ph), i.e. Me₃SiCHR → ^-CH₂(Me)₂SiCH₂R. In the particular case of the formation of PhCH₂^- from Me₃SiCHPh, i.e. Me₃SiCHPh → ^-CH₂(Me)₂SiCH₂Ph → PhCH₂^- +Me₂Si=CH₂, the proton transfer competes with scrambling of all hydrogens in the decomposing ion.