Abstract
Actinyl species, [AnO2]2+, are well-known derivatives of the f-block because of their natural occurrence and essential roles in the nuclear fuel cycle. Along with their nitrogen analogues, [An(NR)2]2+, actinyls are characterized by their two strong trans-An–element multiple bonds, a consequence of the inverse trans influence. We report that these robust bonds can be weakened significantly by increasing the number of multiple bonds to uranium, as demonstrated by a family of uranium(VI) dianions bearing four U–N multiple bonds, [M]2[U(NR)4] (M = Li, Na, K, Rb, Cs). Their geometry is dictated by cation coordination and sterics rather than by electronic factors. Multiple bond weakening by the addition of strong π donors has the potential for applications in the processing of high-valent actinyls, commonly found in environmental pollutants and spent nuclear fuels.
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Acknowledgements
This work was funded by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences of the US Department of Energy (DOE) through Grants DE-SC0008479 (S.C.B.) and USDOE/DESC002183 (L.G., J.X. and D.R.). L.G. used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the US DOE under contract no. DE-AC02-05CH11231. The Prospector X-ray diffractometer was funded by NSF Grant DMR 1337296. We thank S. Odoh for useful discussion.
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N.H.A. and S.C.B. conceived and designed the experiments. N.H.A. synthesized all the compounds. J.X., D.R. and L.G. performed the computations. N.H.A. and M.Z. performed the crystallographic analysis. N.H.A., J.X. and S.C.B. co-wrote the manuscript.
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Crystallographic data for compound 2-Na (CIF 746 kb)
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Crystallographic data for compound 2-Rb (CIF 571 kb)
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Crystallographic data for compound 2-Cs (CIF 1111 kb)
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Crystallographic data for compound 2-K(crypt) (CIF 1308 kb)
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Crystallographic data for compound 2-K (CIF 4986 kb)
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Anderson, N., Xie, J., Ray, D. et al. Elucidating bonding preferences in tetrakis(imido)uranate(VI) dianions. Nature Chem 9, 850–855 (2017). https://doi.org/10.1038/nchem.2767
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DOI: https://doi.org/10.1038/nchem.2767
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