Reductive Behavior of [Fe2(CO)42-dmpe){μ-(SCH2)2NBn}]: Effect of Symmetrization on the Rotated Conformation in FeI-FeI Models of [2Fe]H Subsite of [Fe-Fe]­H2ases

Authors

  • Luca De Gioia,

    1. Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy, http://www.unimib.it
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  • Catherine Elleouet,

    Corresponding author
    1. Université de Bretagne Occidentale; CNRS, UMR 6521 “Chimie, Electrochimie Moléculaires et Chimie Analytique”, CS 93837, 29238 Brest-Cedex 3, France, http://www.univ-brest.fr/
    • Catherine Elleouet, Université de Bretagne Occidentale; CNRS, UMR 6521 “Chimie, Electrochimie Moléculaires et Chimie Analytique”, CS 93837, 29238 Brest-Cedex 3, France===

      Philippe Schollhammer, Université de Bretagne Occidentale; CNRS, UMR 6521 “Chimie, Electrochimie Moléculaires et Chimie Analytique”, CS 93837, 29238 Brest-Cedex 3, France===

      Giuseppe Zampella, Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy===

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  • Sabrina Munery,

    1. Université de Bretagne Occidentale; CNRS, UMR 6521 “Chimie, Electrochimie Moléculaires et Chimie Analytique”, CS 93837, 29238 Brest-Cedex 3, France, http://www.univ-brest.fr/
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  • François Y. Pétillon,

    1. Université de Bretagne Occidentale; CNRS, UMR 6521 “Chimie, Electrochimie Moléculaires et Chimie Analytique”, CS 93837, 29238 Brest-Cedex 3, France, http://www.univ-brest.fr/
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  • Philippe Schollhammer,

    Corresponding author
    1. Université de Bretagne Occidentale; CNRS, UMR 6521 “Chimie, Electrochimie Moléculaires et Chimie Analytique”, CS 93837, 29238 Brest-Cedex 3, France, http://www.univ-brest.fr/
    • Catherine Elleouet, Université de Bretagne Occidentale; CNRS, UMR 6521 “Chimie, Electrochimie Moléculaires et Chimie Analytique”, CS 93837, 29238 Brest-Cedex 3, France===

      Philippe Schollhammer, Université de Bretagne Occidentale; CNRS, UMR 6521 “Chimie, Electrochimie Moléculaires et Chimie Analytique”, CS 93837, 29238 Brest-Cedex 3, France===

      Giuseppe Zampella, Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy===

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  • Jean Talarmin,

    1. Université de Bretagne Occidentale; CNRS, UMR 6521 “Chimie, Electrochimie Moléculaires et Chimie Analytique”, CS 93837, 29238 Brest-Cedex 3, France, http://www.univ-brest.fr/
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  • Giuseppe Zampella

    Corresponding author
    1. Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy, http://www.unimib.it
    • Catherine Elleouet, Université de Bretagne Occidentale; CNRS, UMR 6521 “Chimie, Electrochimie Moléculaires et Chimie Analytique”, CS 93837, 29238 Brest-Cedex 3, France===

      Philippe Schollhammer, Université de Bretagne Occidentale; CNRS, UMR 6521 “Chimie, Electrochimie Moléculaires et Chimie Analytique”, CS 93837, 29238 Brest-Cedex 3, France===

      Giuseppe Zampella, Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy===

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  • dmpe = 1,2-bis(dimethylphosphino)ethane, (CH3)2PCH2CH2P(CH3)2.

Abstract

The reduction of the compound [Fe2(CO)42-dmpe){μ-(SCH2)2NBn}] [dmpe = 1,2-bis(dimethylphosphino)ethane], which is considered as an FeI-FeI model of the [2Fe]H subsite of [Fe-Fe]H2ases with a rotated conformation in the solid state, was investigated by cyclic voltammetry. Under reductive conditions, [Fe2(CO)42-dmpe){μ-(SCH2)2NBn}] undergoes electron-transfer-catalyzed isomerization to afford an isomer featuring a bridging diphosphine [Fe2(CO)4(μ-dmpe){μ-(SCH2)2NBn}]. Comparison of the crystallographic structures of the two isomers affords unique and direct experimental evidence that dissymmetrical coordination of the chelate ligand is required to promote the rotated conformation at one iron atom in this compound. DFT calculations were performed to rationalize this isomerization process and the slightly distorted structure of [Fe2(CO)4(μ-dmpe){μ-(SCH2)2NBn}]. The symmetrization of the coordination sphere results in the disruption of the agostic interaction that stabilized the rotated isomer.

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