Heterolytic Cleavage of Hydrogen by an Iron Hydrogenase Model: An Fe‐H⋅⋅⋅H‐N Dihydrogen Bond Characterized by Neutron Diffraction |
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Authors: | Dr Tianbiao Liu Dr Xiaoping Wang Dr Christina Hoffmann Dr Daniel L DuBois Dr R Morris Bullock |
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Institution: | 1. Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (USA);2. Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (USA) |
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Abstract: | Hydrogenase enzymes in nature use hydrogen as a fuel, but the heterolytic cleavage of H? H bonds cannot be readily observed in enzymes. Here we show that an iron complex with pendant amines in the diphosphine ligand cleaves hydrogen heterolytically. The product has a strong Fe‐H???H‐N dihydrogen bond. The structure was determined by single‐crystal neutron diffraction, and has a remarkably short H???H distance of 1.489(10) Å between the protic N‐Hδ+ and hydridic Fe‐Hδ? part. The structural data for CpFe H (PtBu2NtBu2 H )]+ provide a glimpse of how the H? H bond is oxidized or generated in hydrogenase enzymes. These results now provide a full picture for the first time, illustrating structures and reactivity of the dihydrogen complex and the product of the heterolytic cleavage of H2 in a functional model of the active site of the FeFe] hydrogenase enzyme. |
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Keywords: | enzyme models hydrogen hydrogenases iron neutron diffraction |
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