Reversible Redox Chemistry of Anionic Imidazole-2-thione-Fused 1,4-Dihydro-1,4-diphosphinines.

Anionic 1,4-dihydro-1,4-diphosphinines were synthesized from tricyclic 1,4-diphosphinines and isolated as blue powdery salts M[ 2a - 2c ]. Reaction of solutions of these monoanions with iodomethane led to P -methylated compounds 3a - 3c . An oxidation/reduction cycle was examined, starting from solutions of K[ 2a ] via P-P coupled product 4a and back to K[ 2a ], and the recyclability and redox chemistry of this cycle were confirmed by experimental and simulated cyclic voltammetry analysis, which is proposed as a potential 2-electron cathode for rechargeable cells. TD-DFT studies were used to examine species that might be involved in the process.