Fumio Okada

Metastable ion study of organosilicon compounds. Part IX. CH3COOSi(CH3)3 and CF3COOSi(CH3)3

Abstract The unimolecular metastable dissociation of trimethylsilyl acetate, CH3COOSi(CH3)3 (1), and its fluorine analogue, trimethylsilyl trifluoroacetate, CF3COOSi(CH3)3 (2), upon electron impact have been investigated by means of a B/E linked scan, high resolution data, and D-labeling. The results are compared with those of the carbon analogue, tert-butyl acetate, CH3COOC(CH3)3 (3). No molecular ion of any of these compounds can be observed, but loss of CH3 occurs exclusively from the trimethylsilyl or tert-butyl groups. The fragmentation of 1+ is slightly different from that of 3+, and quite different from that of 2+, In the case of 3+, (CH3)2CO is eliminated from [3-CH3]+, giving rise to the peak at m z 43 , but the loss of (CH3)2SiO does not occur from [1-CH3]+. In the case of 2+·, an interesting fluorine atom (F) migration is observed.

Metastable ion study of organosilicon compounds VIII. Dimethoxydiphenylsilane

Abstract The spontaneous unimolecular dissociation reaction of the molecular ion of dimethoxydiphenylsilane (1) has been investigated by mass-analyzed ion kinetic energy spectroscopy, collision-induced dissociation, a D-labeling study and high resolution data. The results are compared with those of the corresponding carbon analogue, dimethoxydiphenylmethane (2). The fragmentation of the metastable 1.+ is more complex than that of 2.+. The latter eliminates the methoxy radical only, whereas the former eliminates methanol and benzene molecules, and C7H7 radical in addition to the formation of the molecular ion of biphenyl (3). The intensity of the [MC6H5]+ ion at m/z = 167 is much larger than that of [MOCH3]+ ion at m/z = 213 in the normal mass spectrum of 1. On the contrary, in the case of 2, the intensity of [MC6H5]+ ions is smaller than that of [MOCH3]3+ ions.