Two-electon-transfer redox systems: Part 6. Two-electron oxidation of hexakis(benzylthio)benzene—a study by electrolysis and cyclic voltammetry

The anodic oxidation of the oligo-thioether hexakis(benzylthio)benzene in a dichloromethane+NBu4PF6 electrolyte is investigated by several complementary techniques: cyclic voltammetry, ESR spectroscopy, and macroscopic electrolysis (including fractional electrolysis in combination with the determination of open circuit potentials, i.e. ‘potentiometric titration’). While ESR spectroscopy proves the formation of a π-delocalized radical cation, the electrochemical techniques indicate further oxidation to a dicationic stage, which undergoes follow-up reactions. Analysis of fractional electrolysis results clearly shows strong potential compression for the two electron transfer steps with a difference of formal potentials ΔE°=23 mV. This value is succesfully used to simulate the cyclic voltammograms of the starting compound.