Metastable ion study of organosilicon compounds part II—hexamethyldisiloxane

Abstract

Abstract Unimolecular reactions of the metastable silicenium ion (CH 3 ) 3 SiOSi(CH 3 ) 2 + generated by dissociative ionization of bexamethyldisiloxane were investigated by mass‐analysed ion kinetic energy (PUKE) Spectrometry. The characteristic fragmentations observed were losses of CH 4 and (CH 3 ) 2 SiO molecules. Complete scrambling of all methyl groups prior to these reactions was found by investigating the MIKE spectra of deuterium labelled analogues (CD 3 ) 3 SiOSi(CH 3 ) 2 + and (CH 3 ) 3 SiOSi(CD 3 ) 3 + . The loss of methane was accompanied by a large kinetic energy release ( T 0.5 = 482 meV). The MIKE spectra of silicenium ions were compared with those of their carbon analogues. The most predominant reaction of metastable (CH 3 ) 3 COC(CH 3 ) 3 + ion was the loss of CH 2 C(C H 3 ) 2 leading to protonated acetone. Significant differences between the ion fragmention characteristics of silicon and carbon compounds were found.