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

Abstract

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. A terminal uranium(VI)–nitride has been shown to be accessible and isolable by a redox strategy whereas a photochemical approach resulted in decomposition. Computational analyses suggest that the U≡N triple bonds are surprisingly comparable to analogous group 6 transition metal nitrides, with a covalent character dominated by 5f rather than 6d contributions.

Cite this article

King, D., Tuna, F., McInnes, E. et al. Isolation and characterization of a uranium(VI)–nitride triple bond. Nature Chem 5, 482–488 (2013). https://doi.org/10.1038/nchem.1642

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