Nature is able to catalyze the interconversion of protons, electrons, and hydrogen using enzymes known as the hydrogenases, of which there are two primary types: [FeFe]- and [NiFe]-hydrogenase. For many enzymes, both the oxidation of hydrogen to protons and electrons, and the reduction of protons to hydrogen occur at high rates.We are interested in functional models of the [FeFe]-hydrogenase active site. Here we present the first example of an [FeFe]-hydrogenase model capable of catalyzing both the oxidation of hydrogen and the reduction of protons. We have previously shown that [Fe2(adtBn)(CO)3(dppv)(FcP*)]2+ ([1  ]2+, adtBn = (SCH2)2NBn, dppv = cis-1,2-bis(diphenylphosphino)ethylene, FcP* = Et2PCH2C5Me4FeCp*, Cp* = C5Me5) functions as a catalyst for hydrogen oxidation in the presence of excess oxidant and base. Preliminary studies suggested that 1   would also evolve hydrogen in acidic solution.  We now report that in the presence of excess acid, 1   is able to reduce protons to yield 50% hydrogen, a process that becomes catalytic when excess reducing agent is employed.  The related, but non-redox complemented complex Fe2(adtBn)(CO)3(dppv)(PMe3)] (2  ) also functions as a catalyst in the presence of excess decamethylferrocene (Fc*, Fc* = Fe(Cp*)2 and acid.

Catalytic hydrogen evolution from redox complemented [FeFe]-hydrogenase models

246th National Meeting (2013)

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