Electrochemical reduction of aromatic thiocarbonyls to the corresponding radical anions

Abstract

Evidence for the presence of radical anions from electrochemical reduction of aromatic thiocarbonyl derivatives has been obtained by means of e.s.r. spectroscopy. A linear dependence between the electromotive force for reducing such a class of compound and that for the corresponding carbonyl derivatives has been observed. Computer-simulated spectral analyses allowed the determination of the proton hyperfine splitting constants. The a_N value for the nitrogen splitting in the 4,4′-dinitro-substituted derivative could be estimated by using a deuterio-substituted compound.

Sets of Coulomb and resonance integrals for double-bonded sulphur have been discussed and a pair of values suggested for the calculation of the spin density distribution. The latter values lead to a qualitative agreement between the energy values of the lowest antibonding orbitals and the experimental reduction potentials.