An elusive vinyl radical isolated as an appended unit in a five-coordinate Co(iii)–bis(iminobenzosemiquinone) complex formed via ligand-centered C–S bond cleavage

Abstract

Redox-active ligand H₄Pra^edt(AP/AP) experienced C–S bond cleavage during complexation reaction with Co(OAc)₂·2H₂O in the presence of Et₃N in CH₃OH in air. Thus, formed complex 1 was composed of two iminobenzosemiquinone radicals in its coordination sphere and an unprecedented stable tethered-vinyl radical. The complex has been characterized by mass, X-ray single crystal, X-band EPR, variable-temperature magnetic moment measurements and DFT based computational study.