A new class of efficient electrocatalysts for the reduction of protons into hydrogen based on the [Mo2O2S2]2+ building block

Oxothiomolybdenum wheels represent a new family of efficient electrocatalysts for the reduction of protons into hydrogen. The present study focuses on the complex [Mo₈S₈O₈(OH) ₈(Ox)]^2- (1) as a lithium salt (Ox^2- = oxalate), which exhibits an electrocatalytic reduction wave of protons in the presence of perchloric acid at about -1.00 V versus SCE in DMF. Efficiency of this new electrocatalyst was evidenced by cyclic voltammetry and coulometry. DFT calculations were reported and bring about data of the protonated state of the catalyst, the first step of the postulated mechanism in the catalytic reaction. Other weak acids such as p-toluenesulfonic acid, trifluoroacetic acid, and acetic acid in DMF were tested and found to be efficient for the reduction of protons. The complex [Mo₁₂S₁₂O₁₂(OH) ₁₂(Trim)]^3- (2) behaves also as an electrocatalyst, functioning at a very low overpotential. Finally, the biomimetic behaviors of this new class of efficient electrocatalysts for hydrogen production mimic those of hydrogenases and compare favorably with their performances.