| Abstract: | Unimolecular reactions of the metastable silicenium ion (CH3)3SiOSi(CH3)2 + generated by dissociative ionization of bexamethyldisiloxane were investigated by mass-analysed ion kinetic energy (PUKE) Spectrometry. The characteristic fragmentations observed were losses of CH4 and (CH3)2Si?O molecules. Complete scrambling of all methyl groups prior to these reactions was found by investigating the MIKE spectra of deuterium labelled analogues (CD3)3SiOSi(CH3)2+ and (CH3)3SiOSi(CD3)3+. The loss of methane was accompanied by a large kinetic energy release (T0.5 = 482 meV). The MIKE spectra of silicenium ions were compared with those of their carbon analogues. The most predominant reaction of metastable (CH3)3COC(CH3)3+ ion was the loss of CH2?C(C H3)2 leading to protonated acetone. Significant differences between the ion fragmention characteristics of silicon and carbon compounds were found. |
