Some enzymes function by coupling substrate turnover with electron transfer from a redox cofactor such as ferredoxin. In the [FeFe]-hydrogenases, nature's fastest catalysts for the production and oxidation of H2, the one-electron redox by a ferredoxin complements the one-electron redox by the diiron active site. In this Article, we replicate the function of the ferredoxins with the redox-active ligand Cp*Fe(C5Me4CH2PEt2) (FcP*). FcP* oxidizes at mild potentials, in contrast to most ferrocene-based ligands, which suggests that it might be a useful mimic of ferredoxin cofactors. The specific model is Fe2[(SCH2)2NBn](CO)3(FcP*)(dppv) (1), which contains the three functional components of the active site: a reactive diiron centre, an amine as a proton relay and, for the first time, a one-electron redox module. By virtue of the synthetic redox cofactor, 2+ exhibits unique reactivity towards hydrogen and CO. In the presence of excess oxidant and base, H2 oxidation by 2+ is catalytic.
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This research was supported by the National Institutes of Health. The authors thank M. Nilges for assistance with EPR and M. Olsen for helpful discussions.
The authors declare no competing financial interests.
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Camara, J., Rauchfuss, T. Combining acid–base, redox and substrate binding functionalities to give a complete model for the [FeFe]-hydrogenase. Nature Chem 4, 26–30 (2012). https://doi.org/10.1038/nchem.1180
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