Stereoelectronic effects in the reactivity of electrogenerated cation radicals of arylselenides

The role of stereoelectronic effects in the electrochemical oxidation of arylselenides Se-substituted by a trimethylsilylmethyl group and those with substituents bearing a carbonyl group have been considered. Although the HOMO of these compounds is formed of pz-type electrons of the ArSe moiety, the predominant contribution from the lone pair of Se makes the heteroatom more susceptible to direct electronic effects than to effects transmitted through the aromatic ring. The σ-p hyperconjugation and the interaction through space were shown to lower the charge localization on the reaction center and to stabilize cation radicals of these compounds, thus changing the control of the potential-determining reaction and promoting second order reactions.