Studies of the EE mechanism. Evidence for reversible dimer formation in electrochemical oxidation of a cyclic dithioether

Abstract

The electrochemical oxidation of 1,5-dithiacyclooctane (DTCO) in acetonitrile has been shown to result in two closely spaced (AI3 = 20 mV) reversible one-electron-transfer steps. A reversible second-order chemical reaction is observed to follow production of the cation radical thus resulting in dimer formation. As the dimer is not electroactive at the potential of the initial process, its further oxidation or reduction must be preceded by dissociation. These conclusions are supported by cyclic voltammetry, controlled potential electrolysis, rotating disk electrode studies, and semiintegral analysis. The unusual ease of the second electron-transfer step is attributed to interactions between the two mesocyclic sulfur atoms.