GAS-PHASE ION-MOLECULE CHEMISTRY OF METHOXY-SUBSTITUTED SILANES - COLLISION-INDUCED DECOMPOSITION OF SILOXIDE IONS LEADING TO ANIONS OF SILAACETALDEHYDE AND METHYL SILAFORMATE

Methoxy-substituted silanes react with hydroxide in a tandem flowing afterglow selected ion flow tube to give a number of siloxide ions. Five of these, (CH3)2(CH3O)SiO-, (CH3O)2(H)SiO-, (CH3O)3SiO-, CH3(CH3O)(H)SiO-, and CH3(CH3O)2SiO-, have been submitted to collision-induced decomposition (CID) conditions. Three of these siloxides are suitable precursor ions for CH3OSiO- and CH3SiO- as well as an isomer of CH3SiO- which is the enolate of silaacetaldehyde. The chemistry of the siloxide ions has been studied by using N2O, CO2, CS2, and COS as has that of many of the ions resulting from CID. The acidity of CH3OSiO- has been determined and compared with that of HSiO-. The reported revision of the acidity of silaacetone takes account of up-to-date reference acidities. © 1990, American Chemical Society. All rights reserved.