Accumulation of Four Electrons on a Terphenyl (Bis)disulfide

Abstract

The activation of N2, CO2 or H2O to energy‐rich products relies on multi‐electron transfer reactions, and consequently it seems desirable to understand the basics of light‐driven accumulation of multiple redox equivalents. Most of the previously reported molecular acceptors merely allow the storage of up to two electrons. We report on a terphenyl compound including two disulfide bridges, which undergoes four‐electron reduction in two separate electrochemical steps, aided by a combination of potential compression and inversion. Under visible‐light irradiation using the organic super‐electron donor tetrakis(dimethylamino)ethylene, a cascade of light‐induced reaction steps is observed, leading to the cleavage of both disulfide bonds. Whereas one of them undergoes extrusion of sulfur to result in a thiophene, the other disulfide is converted to a dithiolate. These insights seem relevant to enhance the current fundamental understanding of photochemical energy storage.