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Harnessing redox activity for the formation of uranium tris(imido) compounds

Nature Chemistry volume 6, pages 919–926 (2014)Cite this article

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Abstract

Classically, late transition-metal organometallic compounds promote multielectron processes solely through the change in oxidation state of the metal centre. In contrast, uranium typically undergoes single-electron chemistry. However, using redox-active ligands can engage multielectron reactivity at this metal in analogy to transition metals. Here we show that a redox-flexible pyridine(diimine) ligand can stabilize a series of highly reduced uranium coordination complexes by storing one, two or three electrons in the ligand. These species reduce organoazides easily to form uranium–nitrogen multiple bonds with the release of dinitrogen. The extent of ligand reduction dictates the formation of uranium mono-, bis- and tris(imido) products. Spectroscopic and structural characterization of these compounds supports the idea that electrons are stored in the ligand framework and used in subsequent reactivity. Computational analyses of the uranium imido products probed their molecular and electronic structures, which facilitated a comparison between the bonding in the tris(imido) structure and its tris(oxo) analogue.

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Figure 1: Synthesis of compounds 1–7.
Figure 2: The molecular structures of complexes 2 through 7 with ellipsoids depicted at 30% probability, as determined by X-ray crystallography.
Figure 3: Visualization of the valence molecular orbitals of 7.
Figure 4: Visualization of the valence molecular orbitals of the trans-O–U–O unit of hypothetical tris-oxo uranium (9).

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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 through Grants DE-AC02-12ER16328 (S.C.B.) and USDOE/DESC002183 (L.G. and S.O.O.). E.J.S. gratefully acknowledges the National Science Foundation (CHE 1362854) for support. The Laboratory Directed Research and Development program of the Lawrence Livermore National Laboratory is acknowledged for support to J.R.W. S.C.B. and E.J.S. are Cottrell Scholars funded by the Research Corporation.

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Authors and Affiliations

  1. Department of Chemistry, H.C. Brown Laboratory, Purdue University, West Lafayette, 47907, Indiana, USA

    Nickolas H. Anderson, Brian A. Schaefer, John J. Kiernicki, Phillip E. Fanwick & Suzanne C. Bart

  2. Department of Chemistry, Supercomputing Institute, and Chemical Theory Centre, University of Minnesota, Minneapolis, 55455, Minnesota, USA

    Samuel O. Odoh, Yiyi Yao & Laura Gagliardi

  3. Department of Chemistry, P. Roy and Diana T. Vagelos Laboratories, University of Pennsylvania, Philadelphia, 19104, Pennsylvania, USA

    Ursula J. Williams, Andrew J. Lewis & Eric J. Schelter

  4. Department of Chemistry, University of Missouri, Columbia, 65211, Missouri, USA

    Mitchell D. Goshert & Justin R. Walensky

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Contributions

N.H.A. and S.C.B. conceived and designed the experiments. N.H.A. synthesized all the compounds. S.O.O., Y.Y., M.D.G., J.R.W. and L.G. performed the computations. U.J.W., A.J.L. and E.J.S. performed and interpreted the SQUID magnetometry. N.H.A., B.A.S., J.J.K. and P.E.F. performed the crystallographic analysis. N.H.A., S.O.O., E.J.S. and S.C.B. co-wrote the manuscript.

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Correspondence to Suzanne C. Bart.

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Supplementary information

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Supplementary information (PDF 3814 kb)

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Crystallographic data for compound 1 (CIF 1230 kb)

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Crystallographic data for compound 2 (CIF 35 kb)

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Crystallographic data for compound 3 (CIF 372 kb)

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Crystallographic data for compound 4 (CIF 369 kb)

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Crystallographic data for compound 5 (CIF 54 kb)

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Crystallographic data for compound 6 (CIF 65 kb)

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Crystallographic data for compound 7 (CIF 1319 kb)

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Crystallographic data for compound 8 (CIF 73 kb)

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Anderson, N., Odoh, S., Yao, Y. et al. Harnessing redox activity for the formation of uranium tris(imido) compounds. Nature Chem 6, 919–926 (2014). https://doi.org/10.1038/nchem.2009

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