Article | Published:

Ammonia formation by a thiolate-bridged diiron amide complex as a nitrogenase mimic

Nature Chemistry volume 5, pages 320326 (2013) | Download Citation

Abstract

Although nitrogenase enzymes routinely convert molecular nitrogen into ammonia under ambient temperature and pressure, this reaction is currently carried out industrially using the Haber–Bosch process, which requires extreme temperatures and pressures to activate dinitrogen. Biological fixation occurs through dinitrogen and reduced NxHy species at multi-iron centres of compounds bearing sulfur ligands, but it is difficult to elucidate the mechanistic details and to obtain stable model intermediate complexes for further investigation. Metal-based synthetic models have been applied to reveal partial details, although most models involve a mononuclear system. Here, we report a diiron complex bridged by a bidentate thiolate ligand that can accommodate HN=NH. Following reductions and protonations, HN=NH is converted to NH3 through pivotal intermediate complexes bridged by N2H3 and NH2 species. Notably, the final ammonia release was effected with water as the proton source. Density functional theory calculations were carried out, and a pathway of biological nitrogen fixation is proposed.

  • Compound C26H34Fe2S2

    Bis(η5-pentamethylcyclopentadienyl)-(μ-η24- benzene-1,2-dithiolate)diiron

  • Compound C26H36Fe2N2S2

    Bis(η5-pentamethylcyclopentadienyl)-(μ-η22-benzenedithiolate)-(μ-η11-diazene)diiron

  • Compound C27H38Fe2N2S2

    Bis(η5-pentamethylcyclopentadienyl)-(μ-η22-benzenedithiolate)-(μ-η11-methyldiazene)diiron

  • Compound C26H36F6Fe2N2PS2

    Bis(η5-pentamethylcyclopentadienyl)-(μ-η22-benzenedithiolate)-(μ-η11-diazene)diiron hexafluorophosphate

  • Compound C27H38F6Fe2N2PS2

    Bis(η5-pentamethylcyclopentadienyl)-(μ-η22-benzenedithiolate)-(μ-η11-methyldiazene)diiron hexafluorophosphate

  • Compound C50H57BFe2N2S2

    Bis(η5-pentamethylcyclopentadienyl)-(μ-η12-benzenedithiolate)-(μ-η12-hydrazido)diiron tetraphenylborate

  • Compound C51H59BFe2N2S2

    Bis(η5-pentamethylcyclopentadienyl)-(μ-η12-benzenedithiolate)-(μ-η12-methylhydrazido)diiron tetraphenylborate

  • Compound C58H49BF24Fe2N2S2

    Bis(η5-pentamethylcyclopentadienyl)-(μ-η12-benzenedithiolate)-(μ-η12-hydrazido)diiron tetrakis(3,5-bis(trifluoromethyl)phenyl)borate

  • Compound C50H56BFe2NS2

    Bis(η5-pentamethylcyclopentadienyl)-(μ-η22-benzenedithiolate)-(μ-amide)diiron tetraphenylborate

  • Compound C51H58BFe2NS2

    Bis(η5-pentamethylcyclopentadienyl)-(μ-η22-benzenedithiolate)-(μ-methylamide)diiron tetraphenylborate

  • Compound C51H56BFe2NOS2

    Carbonyl bis(η5-pentamethylcyclopentadienyl)-(μ-η12-benzenedithiolate)-(μ-amide)diiron tetraphenylborate

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Acknowledgements

This work was supported by the National Natural Science Foundation of China (nos 21231003, 21174023, 21104008, 21076037, 21028001, 20972022) and the ‘111’ project of the Ministry of Education of China. The authors also thank the Network and Information Center of Dalian University of Technology for providing some of the computational resources.

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Author notes

    • Yang Li
    •  & Ying Li

    These authors contributed equally to this work

Affiliations

  1. State Key Laboratory of Fine Chemicals, School of Pharmaceutical Science and Technology, Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, 2 Linggong Road, Dalian 116024, China

    • Yang Li
    • , Ying Li
    • , Baomin Wang
    • , Yi Luo
    • , Dawei Yang
    • , Peng Tong
    • , Jinfeng Zhao
    • , Lun Luo
    • , Yuhan Zhou
    • , Si Chen
    • , Fang Cheng
    •  & Jingping Qu

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Contributions

J.Q. and B.W. supervised the project. J.Q. and Ya.L. conceived and designed the experiments. Ya.L., Yi.L., D.Y. and P.T. performed the experiments. Y.Lu., L.L. and S.C. performed the computational studies. J.Q., Ya.L., B.W. and F.C. co-wrote the paper. J.Z. and Y.Z. analysed the data. All authors discussed the results and commented on the manuscript.

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The authors declare no competing financial interests.

Corresponding author

Correspondence to Jingping Qu.

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    Crystallographic data for compound 1

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    Crystallographic data for compound 2a[PF6]

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    Crystallographic data for compound 2b

  4. 4.

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    Crystallographic data for compound 2b[PF6]

  5. 5.

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    Crystallographic data for compound 3a[BAr(F)4]

  6. 6.

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    Crystallographic data for compound 3b[BPh4]

  7. 7.

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    Crystallographic data for compound 4a[BPh4]

  8. 8.

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DOI

https://doi.org/10.1038/nchem.1594

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