Stereoelectronic effects in the reactivity of electrogenerated cation radicals of arylselenides

The role of stereoelectronic effects in the electrochemical oxidation of ar ylselenides Se-substituted by a trimethylsilylmethyl group and those with s ubstituents bearing a carbonyl group have been considered. Although the HOM O of these compounds is formed of p(z)-type electrons of the ArSe moiety, t he predominant contribution from the lone pair of Se makes the heteroatom m ore susceptible to direct electronic effects than to effects transmitted th rough the aromatic ring. The sigma -p hyperconjugation and the interaction through space were shown to lower the charge localization on the reaction c enter and to stabilize cation radicals of these compounds, thus changing th e control of the potential-determining reaction and promoting second order reactions. (C) 2000 Elsevier Science B.V. All rights reserved.