Thermochemistry of arylselanyl radicals and the pertinent ions in acetonitrile.

Reduction and oxidation potentials of a series of parasubstituted phenylselanyl radicals, XC(6)H(4)Se(*), have been measured using photomodulated voltammetry in acetonitrile. The thermodynamic significance of these data was substantiated through a study of the oxidation process of the pertinent selenolates in linear sweep voltammetry. Both the reduction and the oxidation potentials correlate linearly with the Hammett substituent coefficients sigma and sigma(+) leading in the latter case to slopes, rho(+), of 2.