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Organometallic neptunium(III) complexes

Nature Chemistry volume 8, pages 797–802 (2016)Cite this article

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Abstract

Studies of transuranic organometallic complexes provide a particularly valuable insight into covalent contributions to the metal–ligand bonding, in which the subtle differences between the transuranium actinide ions and their lighter lanthanide counterparts are of fundamental importance for the effective remediation of nuclear waste. Unlike the organometallic chemistry of uranium, which has focused strongly on UIII and has seen some spectacular advances, that of the transuranics is significantly technically more challenging and has remained dormant. In the case of neptunium, it is limited mainly to NpIV. Here we report the synthesis of three new NpIII organometallic compounds and the characterization of their molecular and electronic structures. These studies suggest that NpIII complexes could act as single-molecule magnets, and that the lower oxidation state of NpII is chemically accessible. In comparison with lanthanide analogues, significant d- and f-electron contributions to key NpIII orbitals are observed, which shows that fundamental neptunium organometallic chemistry can provide new insights into the behaviour of f-elements.

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Figure 1: Synthesis of mono- and dinuclear bis(arene)-bound Np(III) LAr complexes 1 and 2 from the spontaneous reduction of the NpIV starting material.
Figure 2: Molecular structures of the three organometallic NpIII complexes.
Figure 3: Reduction of 1 to form 3a.
Figure 4: Ratio between the imaginary part of the a.c. magnetic susceptibility and the static (d.c.) susceptibility measured for [(LAr)NpCl] (1) as a function of temperature and for different frequencies.
Figure 5: MO diagrams for 1c-MI (M = Sm, U, Np).

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Acknowledgements

Experiments were supported by the European FP7 TALISMAN project, under contract with the European Commission, the JRC ITU USERLAB programme, the University of Edinburgh, European Cooperation in Science and Technology action CM1006 and the Engineering and Physical Sciences Research Council EP/H004823/1 and EP/M010554/1. M.S.D. acknowledges the European Commission for support in the frame of the Training and Mobility of Researchers programme. We thank G. Nichol for help with the X-ray crystallography, A. Morgenstern for help with data collection and the Organometallic Chemistry Laboratory, CENT, University of Warsaw, for additional data collection. N.K. thanks the UCL High Performance Computing Facility (Legion@UCL), the University of Manchester's computational shared facility and associated support staff and services.

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Author notes

  1. Joy H. Farnaby

    Present address: Present address: Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK,

Authors and Affiliations

  1. EaStCHEM School of Chemistry, University of Edinburgh, The King's Buildings, Edinburgh, EH9 3FJ, UK

    Michał S. Dutkiewicz, Joy H. Farnaby, Jason B. Love & Polly L. Arnold

  2. European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, Karlsruhe, D-76125, Germany

    Michał S. Dutkiewicz, Christos Apostolidis, Eric Colineau, Olaf Walter, Nicola Magnani & Roberto Caciuffo

  3. School of Physical Sciences (Chemistry), University of Tasmania, Private Bag 75, Hobart, 7001, Tasmania, Australia

    Michael G. Gardiner

  4. Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK

    Nikolas Kaltsoyannis

  5. School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK

    Nikolas Kaltsoyannis

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Contributions

M.S.D. synthesized and purified the compounds and collected and analysed synthetic data; J.H.F. provided ligand samples and analysed synthetic data; C.A. collected and analysed synthetic data; E.C. collected and analysed magnetic data; O.W. collected and analysed crystallographic data; N.M. analysed magnetic data; M.G.G. provided ligand samples; J.B.L. designed the study, analysed the data and wrote the manuscript; N.K. designed the computational study, carried out and analysed the calculations and wrote the manuscript; R.C. designed the study, analysed the data and wrote the manuscript; P.L.A. designed the study, analysed the data and wrote the manuscript.

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Correspondence to Polly L. Arnold.

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The authors declare no competing financial interests.

Supplementary information

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Supplementary information (PDF 1751 kb)

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Crystallographic data for compound 1. (CIF 1408 kb)

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Crystallographic data for compound 2. (CIF 665 kb)

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Crystallographic data for compound 3. (CIF 280 kb)

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Dutkiewicz, M., Farnaby, J., Apostolidis, C. et al. Organometallic neptunium(III) complexes. Nature Chem 8, 797–802 (2016). https://doi.org/10.1038/nchem.2520

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