Structural and functional modelling of nickel-iron hydrogenases

Hydrogenases are enzymes able to efficiently catalyze the interconversion H2/2H+ + 2e- at potentials near the thermodynamic equilibrium. In the active site of nickel-iron hydrogenases, an iron atom has two cyanide ligands and a carbonyl ligand. The potential applications in the framework of a hydrogen economy and the originality of the structure of this active site make that the synthesis of structural and functional models is very important. Two new hetero bimetallic nickel-ruthenium models have then been prepared, this last ones being isoelectronic of iron. Their preparation, their structural and spectroscopic characterization are presented as well as a study of their catalytic reactivity for protons electroreduction revealing a cooperative catalytic effect between the two metals. (O.M.)