On the electroreduction mechanism of halobenzenes. Part I. A quantum chemical approach

The half-wave potentials of various halobenzene derivatives in aprotic solvents correlate with the charge on the halogen atom being reduced and with the energy of the first unoccuppied σ molecular orbital, calculated using the MNDO method. These correlations explain the ortho effect observed in the dihalogen derivatives. Open-shell calculations of the radical anions demonstrate their existence as metastable intermediates. Chlorobenzene has been chosen as a model in order to study the breaking of the CX bond by the reaction coordinate method. According to these results, two possible reduction mechanisms are discussed. © 1987.