Heterolytic cleavage of hydrogen by an iron hydrogenase model: An Fe-H⋯H-N dihydrogen bond characterized by neutron diffraction

Tianbiao Liu, Xiaoping Wang, Christina Hoffmann, Daniel L. Dubois, R. Morris Bullock

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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 [Cp C 5F 4NFeH(PtBu2NtBu 2H)]+ 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. Caught in the act: The addition of H2 to a synthetic iron complex containing a pendant amine (a model complex for [FeFe] hydrogenase) leads to facile heterolytic cleavage of H2. Neutron diffraction indicates a very short H⋯H bond distance of 1.489(10) Å in the Fe-H⋯H-N complex, thus providing a glimpse of how the H-H bond is oxidized in hydrogenase enzymes.

Original languageEnglish
Pages (from-to)5300-5304
Number of pages5
JournalAngewandte Chemie - International Edition
Issue number21
Publication statusPublished - May 19 2014



  • enzyme models
  • hydrogen
  • hydrogenases
  • iron
  • neutron diffraction

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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