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Ammonia formation by metal–ligand cooperative hydrogenolysis of a nitrido ligand

Nature Chemistry volume 3, pages 532537 (2011) | Download Citation

Abstract

Bioinspired hydrogenation of N2 to ammonia at ambient conditions by stepwise nitrogen protonation/reduction with metal complexes in solution has experienced remarkable progress. In contrast, the highly desirable direct hydrogenation with H2 remains difficult. In analogy to the heterogeneously catalysed Haber–Bosch process, such a reaction is conceivable via metal-centred N2 splitting and unprecedented hydrogenolysis of the nitrido ligands to ammonia. We report the synthesis of a ruthenium(IV) nitrido complex. The high nucleophilicity of the nitrido ligand is demonstrated by unusual N–C coupling with π-acidic CO. Furthermore, the terminal nitrido ligand undergoes facile hydrogenolysis with H2 at ambient conditions to produce ammonia in high yield. Kinetic and quantum chemical examinations of this reaction suggest cooperative behaviour of a phosphorus–nitrogen–phosphorus pincer ligand in rate-determining heterolytic hydrogen splitting.

  • Compound C20H44N2P2Ru

    Nitrido(2-(di-tert-butylphosphino-κP-ethyl)amidoruthenium(IV)

  • Compound C22H44N2O2P2Ru

    Isocyanatocarbonyl(2-(di-tert-butylphosphino-κP-ethyl)amidoruthenium(II)

  • Compound C20H49NP2Ru

    Tetrahydrido(2-(di-tert-butylphosphino-κP-ethyl)amineruthenium(IV)

  • Compound C20H47NP2Ru

    Trihydrido(2-(di-tert-butylphosphino-κP-ethyl)amidoruthenium(IV)

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Acknowledgements

This work was partially funded by the Emmy Noether programme of the Deutsche Forschungsgemeinschaft (SCHN950/2-1). B.A. thanks the international graduate school NanoCat and the Technische Universität München Graduate School for support. The work in Frankfurt was supported by the Beilstein Institute as part of the NanoBiC research cooperative (project eNet). Computer time and excellent support, in particular by G. Laubender, was provided by the Center for Scientific Computing Frankfurt.

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Affiliations

  1. Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching b. München, Germany

    • Bjorn Askevold
    • , Jorge Torres Nieto
    •  & Eberhardt Herdtweck
  2. Department Chemie und Pharmazie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 1, 91058 Erlangen, Germany

    • Bjorn Askevold
    •  & Sven Schneider
  3. Insitut für Anorganische und Analytische Chemie, Goethe-Universität, Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany

    • Samat Tussupbayev
    • , Martin Diefenbach
    •  & Max C. Holthausen

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Contributions

B.A. and J.T.N. performed the synthetic work and spectrosopic examination, S.T. and M.D. the quantum chemical study and E.H. the crystallographic characterization, respectively. S.S. and M.C.H. designed and supervised the experimental and computational studies, respectively. The paper was written by B.A., S.T., M.D., M.C.H. and S.S. and all the authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Max C. Holthausen or Sven Schneider.

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https://doi.org/10.1038/nchem.1051

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