Gas phase studies of silacyclobutanes: Recent developments employing triple quadrupole detection

Four silacyclobutyl anions have been prepared and studied by gas phase ion-molecule chemistry using newly modified tandem flowing afterglow instrumentation. These silacyclobutyl anions, which include a pentacoordinate adduct of 1,1-dimethylsilacyclobutane and fluoride and an alpha-silylcarbanion, siloxide, and mercaptide corresponding to 1,1-dimethylsilacyclobutane, have been characterized by their chemical reactivity and collision-induced loss of ethylene under a variety of conditions. The C-H, O-H, and S-H gas phase acidities of 1,1-dimethylsilacyclobutane, 1-hydroxy-1-methylsilacyclobutane, and 1-mercapto-1-methylsilacyclobutane have been measured and show no effect of the silacyclobutyl attachment. The full capabilities of the newly modified instrumentation include the mass selection of ions, their chemical characterization, collision-induced dissociation of both mass selected ions and those prepared by chemical reactions, and triple quadrupole detection.