A ruthenium-based biomimetic hydrogen cluster for efficient photocatalytic hydrogen generation from formic acid

A ruthenium-based biomimetic hydrogen cluster, [Ru₂(CO)₆(μ-SCH₂CH₂CH₂S)] (1), has been synthesized and, in the presence of the P ligand tri(o-tolyl)phosphine, demonstrated efficient photocatalytic hydrogen generation from formic acid decomposition. Turnover frequencies (TOFs) of 5500 h^-1 and turnover numbers (TONs) over 24 700 were obtained with less than 50 ppm of the catalyst, thus representing the highest TOFs for ruthenium complexes as well as the best efficiency for photocatalytic hydrogen production from formic acid. Moreover, 1 showed high stability with no significant degradation of the photocatalyst observed after prolonged photoirradiation at 90 C. Chemical copycat: A diruthenium complex with efficient photocatalytic hydrogen evolution from formic acid decomposition was developed by mimicking an [FeFe]-based hydrogen cluster (see figure). The catalytic activities obtained with less than 50 ppm of the catalyst amount represented the highest turnover frequency for ruthenium complexes as well as the best efficiency for photocatalytic hydrogen production from formic acid.