Optimizing Photocatalytic H 2 Production by Introduction of Pyrazinyls to WRCs and a New tris-Rhenium Photosensitizer.

The replacement of pyridyl by pyrazinyl in ligands of polypyridyl-based cobalt water reducing catalysts (WRC) shifts reduction potentials anodically. Together with a new, trinuclear Re I photosensitizer, these WRCs show strongly improved photocatalytic performances in turnover numbers (TONs) and maximal H 2 evolution rate. Depending on the catalyst structure, up to 65 kTONs at 1 μM WRC concentration were reached. Under electrocatalytic conditions in both DMF and H 2 O, one of the reported WRCs displays remarkable stability, producing H 2 steadily over 21 and 14 d, respectively.