CHEMISTRY OF ALKALI METAL-UNSATURATED HYDROCARBON ADDUCTS .10. ELECTRON-TRANSFER REACTIONS OF ALPHA,BETA-UNSATURATED ORGANOSILANES

The chemical behavior of alkali metal adducts of α,β-unsaturated organosilanes was investigated by generating the adducts with lithium or potassium metal in donor solvents at -78°C and studying the ensuing reduction, bimolecular coupling, cleavage and isomerization processes. Chosen for study were the triphenylvinyl derivatives of silicon, germanium and tin, as well as other vinyl-, phenyl-, allyl-, 1,3-alkadienyl-, 1-alkynyl- and cyclopropyl-silanes. By assessing gradations in substituent reactivity toward alkali metal, an empirical ordering of electron affinity for these substituents on silicon was determined: 1,3-alkadienyl > 1-alkynyl > 1-alkenyl > phenyl > > 2-alkenyl or cyclopropyl. Where available, ESR data were used to explain the reactivity and the reaction pathway observed for radical anion intermediates. Where such information was unobtainable, the behavior of unstable radical anions was ascribed to variations in pπ → dπ stabilization. © 1979.