Photolytic generation of radical anions and dianions and Group IVB organometallic adducts of β-diketones. An electron spin resonance study on the effects of fluorine substitution and crown ethers

Abstract

Using CF₃COCH₂COCF₃, 2-thienyl-COCH₂COCF₃ and model diketones, we have successfully demonstrated the formation and the observation of the e.s.r. of radical anions by photoreduction with amines and the radical dianions by photochemical reactions with THF and alkali-metal tetraphenylborates. The e.s.r. results shed some light on the reaction mechanisms of these photochemical processes. The chemical selectivity of different organometallic radicals towards the tautomers of CF₃COCH₂COCF₃ is further illustrated by having organosilyl radicals add mainly to the enol form while the organotin radicals co-ordinate only to the keto-form of the diketone.