Unstable methoxycyclosiloxanes n (n = 2,3): Thermal generation and direct mass spectral studies

Article abstract of DOI:10.1016/0022-328X(90)80019-V

Direct evidence for formation of unstable methoxy cyclosiloxanes <(CH3O)2SIO>2 (1) and <(CH3O)2SIO>3 (2) in the gas phase has been obtained by a mass-spectral study of the vacuum pyrolysis of 3,3-dimethoxy-6-oxa-3-silabicyclo<3.1.0>hexane (4).Intermediates 1 and 2 have been detected in the mass spectra of the pyrolysis products of 4 as the corresponding molecular ions, and identified from their exact masses and compositions.The metastable transitions recorded by B/E scan show the fragmentation trends of 1, 2 and 4 under electron impact (70 eV).The ionization energies (IE), determined for 1 (8.81 +/- 0.1 eV) and 2 (8.50 +/- 0.1 eV) are considerably lower than the IE of linear methoxysubstituted silanes and alkenes.