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One-pot, room-temperature conversion of dinitrogen to ammonium chloride at a main-group element

Abstract

The industrial reduction of dinitrogen (N2) to ammonia is an energy-intensive process that consumes a considerable proportion of the global energy supply. As a consequence, species that can bind N2 and cleave its strong N–N bond under mild conditions have been sought for decades. Until recently, the only species known to support N2 fixation and functionalization were based on a handful of metals of the s and d blocks of the periodic table. Here we present one-pot binding, cleavage and reduction of N2 to ammonium by a main-group species. The reaction—a complex multiple reduction–protonation sequence—proceeds at room temperature in a single synthetic step through the use of solid-phase reductant and acid reagents. A simple acid quench of the mixture then provides ammonium, the protonated form of ammonia present in fertilizer. The elementary reaction steps in the process are elucidated, including the crucial N–N bond cleavage process, and all of the intermediates of the reaction are isolated.

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Fig. 1: A one-pot, borylene-mediated synthesis of ammonium chloride from N2, and elucidation of the individual reduction–protonation steps involved.
Fig. 2: Schematic of the overall mechanism of the borylene-mediated ammonium synthesis.

Data availability

Crystallographic data for the structures reported in this article have been deposited at the Cambridge Crystallographic Data Centre, under deposition numbers CCDC 1971191 (8), 1971192 (7), 1971193 (5) and 1971194 (6). Copies of the data can be obtained free of charge via https://www.ccdc.cam.ac.uk/structures/. Further data supporting the findings of this study are available from the corresponding author upon reasonable request.

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Acknowledgements

We thank the Deutsche Forschungsgemeinschaft for financial support. M.-A.L. thanks the Natural Sciences and Engineering Research Council of Canada for a postdoctoral fellowship. G.B.-C. thanks the Alexander von Humboldt Foundation for a postdoctoral fellowship.

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Authors

Contributions

Experiments were designed by M.-A.L., G.B.-C., R.D.D. and H.B. and performed by M.-A.L., M.R. and G.B.-C. Data analysis was performed by M.-A.L., G.B.-C. and the article was written by M.-A.L. and R.D.D. X-ray crystallography was performed by G.B.-C. The EPR investigation was performed by I.K. and the NMR experiments were performed by R.B. The project was overseen by H.B. All authors read and commented on the manuscript.

Corresponding author

Correspondence to Holger Braunschweig.

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The authors declare no competing interests.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–30.

Supplementary Data 1

CIF file for compound 5.

Supplementary Data 2

CIF file for compound 6.

Supplementary Data 3

CIF file for compound 7.

Supplementary Data 4

CIF file for compound 8.

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Légaré, MA., Bélanger-Chabot, G., Rang, M. et al. One-pot, room-temperature conversion of dinitrogen to ammonium chloride at a main-group element. Nat. Chem. 12, 1076–1080 (2020). https://doi.org/10.1038/s41557-020-0520-6

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