Département de chimie moléculaire

Hydrogen prodn. through water splitting is one of the most promising solns. for the storage of renewable energy. [NiFe] hydrogenases are organometallic enzymes contg. nickel and iron centers that catalyze hydrogen evolution with performances that rival those of platinum. These enzymes provide inspiration for the design of new mol. catalysts that do not require precious metals. However, all heterodinuclear NiFe models reported so far do not reproduce the Ni-centered reactivity found at the active site of [NiFe] hydrogenases. Here, we report a structural and functional NiFe mimic that displays reactivity at the Ni site. This is shown by the detection of two catalytic intermediates that reproduce structural and electronic features of the Ni-L and Ni-R states of the enzyme during catalytic turnover. Under electrocatalytic conditions, this mimic displays high rates for H2 evolution (second-order rate const. of 2.5 × 104 M-1 s-1; turnover frequency of 250 s-1 at 10 mM H+ concn.) from mildly acidic solns. [on SciFinder(R)]