Homogeneous and Heterogeneous Electron Transfer to Benzyl Phenyl Sulfide

Article abstract of DOI:10.1021/j100286a041

The thermodynamic and kinetic parameters of the elctron transfer (ET) to benzyl phenyl sulfide in DMF have been determined by cyclic voltammetry.The heterogeneous ET has been studied at three different electrodes: Hg, Pt, and glassy carbon.The activation parameters, namely the standard rate constant and the transfer coefficient, corrected for the double-layer contribution, show no significant difference for the three materials.The rate constants for the homogeneous ET to benzyl phenyl sulfide from eight electrogenerated anion radicals have been determined and compared with the corresponding reaction free energies, according to the current theories of the ET process.The results indicate that the ET is an endergonic process driven by a fast bond breaking of the ET product.Both the homogeneous and the heterogeneous reactions are consistent with an outer-sphere adiabatic electron-exchange process, characterized by a relatively high activation free energy.To account for the latter, inner reorganization energies must be considered, together with solvent reorganization.This is an agreement with the easy breaking of the C-S bond in the primari ET product.