Visible light-driven electron transfer and hydrogen generation catalyzed by bioinspired [2Fe2S] complexes

Complexes [{(mu-SCH2)(2)NCH2C6H5){Fe(CO)(2)L-1){Fe(CO)(2)L-2}] (L-1 = CO, L-2 = P(Pyr)(3), 2; L-1 = L-2 = P(Pyr)(3), 3) were prepared, which have the lowest reduction potentials for the mono- and double-CO-displaced diiron complexes reported so far. Hydrogen evolution, driven by visible light, was successfully observed for a three-component system, consisting of a ruthenium polypyridine complex, the biomimetic model complex 2 or 3, and ascorbic acid as both electron and proton donor in CH3CN/H2O. The electron transfer from photogenerated Ru(bPY)(3)(+) to 2 or 3 was detected by laser flash photolysis. Under optimal conditions, the total turnover number for hydrogen evolution was 4.3 based on 2 and 86 based on Ru(bPY)(3)(2+) in a three-hour photolysis.