Evidence for the product of the viologen comproportionation reaction being a spin-paired radical cation dimer
Abstract
The mechanism of the bipyridylium comproportionation reaction has been determined using the redox states of methyl viologen (MV). The reaction, hitherto presumed to follow the stoichiometry MV2++ MV0→ 2 MV+, has been investigated using in situ electrochemical EPR and UV–VIS spectroscopy and been shown to proceed via an intermediate step forming a spin-paired radical cation dimer (MV)22+. Dimer dissociation occurs as a subsequent reaction stage.