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Isolation and characterization of a uranium(VI)–nitride triple bond

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The nature and extent of covalency in uranium bonding is still unclear compared with that of transition metals, and there is great interest in studying uranium–ligand multiple bonds. Although U=O and U=NR double bonds (where R is an alkyl group) are well-known analogues to transition-metal oxo and imido complexes, the uranium(VI)–nitride triple bond has long remained a synthetic target in actinide chemistry. Here, we report the preparation of a uranium(VI)–nitride triple bond. We highlight the importance of (1) ancillary ligand design, (2) employing mild redox reactions instead of harsh photochemical methods that decompose transiently formed uranium(VI) nitrides, (3) an electrostatically stabilizing sodium ion during nitride installation, (4) selecting the right sodium sequestering reagent, (5) inner versus outer sphere oxidation and (6) stability with respect to the uranium oxidation state. Computational analyses suggest covalent contributions to U≡N triple bonds that are surprisingly comparable to those of their group 6 transition-metal nitride counterparts.

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Figure 1: Synthesis of compounds 59 from precursors 14.
Figure 2: Molecular structures of 7, 8, 12 and 13.
Figure 3: Mechanism for the photochemical conversion of 9 into 7 into 8.
Figure 4: Synthesis of compounds 1013 from precursors 2 and 3.
Figure 5: The top three occupied α-spin Kohn–Sham MOs of 7 (hydrogen atoms omitted for clarity).

Change history

  • 10 May 2013

    In the version of this Article originally published online, in the second paragraph of the section 'Synthetic considerations for preparing U≡N triple bonds', compound 7 was referred to instead of compound 12. The relevant text should have read 'The characterization data for 12 fully support its formulation (Supplementary Information). The crystal structure of 12 (Fig. 2c) reveals...' This has been corrected in the HTML and PDF versions of the Article.


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We are grateful to the European Research Council, the UK Engineering and Physical Sciences Research Council, including the National UK Electron Paramagnetic Resonance Facility at Manchester, the University of Nottingham and the UK National Nuclear Laboratory for generous funding and support, the Royal Society for the award of a University Research Fellowship (S.T.L.) and European Cooperation in Science and Technology (COST) Action CM1006 for support.

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D.M.K. synthesized and characterized the compounds. F.T. and E.J.L.M. recorded and analysed the electron paramagnetic resonance data. J.M. carried out and analysed the DFT calculations. W.L. and A.J.B. carried out the X-ray single-crystal structure analyses. S.T.L. originated the central idea, supervised the work, analysed the data and wrote the manuscript with contributions from all the co-authors.

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Correspondence to Stephen T. Liddle.

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King, D., Tuna, F., McInnes, E. et al. Isolation and characterization of a uranium(VI)–nitride triple bond. Nature Chem 5, 482–488 (2013).

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