Cp* – ‐Ruthenium–Nickel‐Based H 2 ‐Evolving Electrocatalysts as Bio‐inspired Models of NiFe Hydrogenases

Three dinuclear nickel–ruthenium complexes [Ni(xbsms)RuCp*(L)](PF 6 ) [H 2 xbsms = 1,2‐bis(4‐mercapto‐3,3‐dimethyl‐2‐thiabutyl)benzene; Cp* = pentamethylcyclopentadienyl; L = CH 3 CN, CO and O 2 ] are reported that act as bio‐inspired mimics of NiFe hydrogenases. Because of an increased electron density at the metal centres in comparison with the previously described [Ni(xbsms)RuCp(L)](PF 6 ) (Cp = cyclopentadienyl) analogues, these compounds catalyze the evolution of hydrogen from Et 3 NH + in DMF with an overpotential reduced by around 50 mV, thereby corroborating a previously established structure–function relationship [ Eur. J. Inorg. Chem. 2007 , 18 , 2613–2626; Chem. Eur. J. 2009 , 1 5, 9350–9364]. In addition, the steric protection provided by the bulky Cp* – ligand results in an increased catalytic rate and stability upon cycling.