Novel redox behavior of [5]radialenes substituted with 1,3-dithiol groups

Only one pair of reversible waves involving a net four-electron transfer has been observed in the redox process of pentakis(1,3-benzodithiol-2-ylidene)cyclopentane (1a), a potent electron-donating molecule. This is the first case of a single-wave four-electron transfer with only one macroscopic redox site in organic redox systems. Normal explicit difference digital simulation analysis assuming Nernstian response has been carried out to elucidate the detailed redox process of 1a. Our studies have shown that 1a mainly follows a two-step two-electron transfer and is converted to the tetracation (1a 4+ ) via the dication (1a 4+ ). The estimated redox potentials for the 1a/1a 2+ and 1a 2+ /1a 4+ couples are 0.394±0.003 and 0.386±0.003 V vs SCE, respectively