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Keywords:

  • Hydrogen;
  • Biomimetic synthesis;
  • Enzyme models;
  • Metalloenzyme models;
  • Electrocatalysis;
  • Nickel;
  • Ruthenium

Abstract

Three dinuclear nickel–ruthenium complexes [Ni(xbsms)RuCp*(L)](PF6) [H2xbsms = 1,2-bis(4-mercapto-3,3-dimethyl-2-thiabutyl)benzene; Cp* = pentamethylcyclopentadienyl; L = CH3CN, CO and O2] 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)](PF6) (Cp = cyclopentadienyl) analogues, these compounds catalyze the evolution of hydrogen from Et3NH+ 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, 15, 9350–9364]. In addition, the steric protection provided by the bulky Cp* ligand results in an increased catalytic rate and stability upon cycling.