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A [FeFe]-hydrogenase model (1) containing a chelating diphosphine ligand with a pendant amine was readily oxidized by Fc⁺ (Fc = Cp₂Fe) to a Fe^IIFe^I complex ([1]⁺), which was isolated at room temperature. The structure of [1]⁺ with a semibridging CO and a vacant apical site was determined by X-ray crystallography. Complex [1]⁺ catalytically activates H₂ at 1 atm at 25 °C in the presence of excess Fc⁺ and P(o-tol)₃. More interestingly, the catalytic activity of [1]⁺ for H₂ oxidation remains unchanged in the presence of ca. 2% CO. A computational study of the reaction mechanism showed that the most favorable activation free energy involves a rotation of the bridging CO to an apical position followed by activation of H₂ with the help of the internal amine to give a bridging hydride intermediate.