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Issue 11, 2013
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Biomimetic model for [FeFe]-hydrogenase: asymmetrically disubstituted diiron complex with a redox-active 2,2′-bipyridyl ligand

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Abstract

[FeFe]-hydrogenases feature a unique active site in which the primary catalytic unit is directly coordinated via a bridging cysteine thiolate to a secondary, redox active [4Fe4S] unit. The goal of this study was to evaluate the impact of a bidentate, redox non-innocent ligand on the electrocatalytic properties of the (μ-S(CH2)3S)Fe2(CO)4L2 family of [FeFe]-hydrogenase models as a proxy for the iron–sulfur cluster. Reaction of the redox non-innocent ligand 2,2′-bipyridyl (bpy) with (μ-S(CH2)3S)Fe2(CO)6 leads to substitution of two carbonyls to form the asymmetric complex (μ-S(CH2)3S)Fe2(CO)42-bpy) which was structurally characterized by single crystal X-ray crystallography. This complex can be protonated by HBF4·OEt2 to form a bridging hydride. Furthermore, electrochemical investigation shows that, at slow scan rates, the complex undergoes a two electron reduction at −2.06 V vs. Fc+/Fc that likely involves reduction of both the bpy ligand and the metal. Electrocatalytic reduction of protons is observed in the presence of three distinct acids of varying strengths: HBF4·OEt2, AcOH, and p-TsOH. The catalytic mechanism depends on the strength of the acid.

Graphical abstract: Biomimetic model for [FeFe]-hydrogenase: asymmetrically disubstituted diiron complex with a redox-active 2,2′-bipyridyl ligand

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Publication details

The article was received on 15 Oct 2012, accepted on 19 Dec 2012 and first published on 21 Dec 2012


Article type: Paper
DOI: 10.1039/C2DT32457A
Citation: Dalton Trans., 2013,42, 3843-3853
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    Biomimetic model for [FeFe]-hydrogenase: asymmetrically disubstituted diiron complex with a redox-active 2,2′-bipyridyl ligand

    S. Roy, T. L. Groy and A. K. Jones, Dalton Trans., 2013, 42, 3843
    DOI: 10.1039/C2DT32457A

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