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Reduction and selective oxo group silylation of the uranyl dication


Uranium occurs in the environment predominantly as the uranyl dication [UO2]2+. Its solubility renders this species a problematic contaminant1,2,3 which is, moreover, chemically extraordinarily robust owing to strongly covalent U–O bonds4. This feature manifests itself in the uranyl dication showing little propensity to partake in the many oxo group functionalizations and redox reactions typically seen with [CrO2]2+, [MoO2]2+ and other transition metal analogues5,6,7,8,9. As a result, only a few examples of [UO2]2+ with functionalized oxo groups are known. Similarly, it is only very recently that the isolation and characterization of the singly reduced, pentavalent uranyl cation [UO2]+ has been reported10,11,12. Here we show that placing the uranyl dication within a rigid and well-defined molecular framework while keeping the environment anaerobic allows simultaneous single-electron reduction and selective covalent bond formation at one of the two uranyl oxo groups. The product of this reaction is a pentavalent and monofunctionalized [O = U ... OR]+ cation that can be isolated in the presence of transition metal cations. This finding demonstrates that under appropriate reaction conditions, the uranyl oxo group will readily undergo radical reactions commonly associated only with transition metal oxo groups. We expect that this work might also prove useful in probing the chemistry of the related but highly radioactive plutonyl and neptunyl analogues found in nuclear waste.

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Figure 1: Reductive silylation of the uranyl dication.
Figure 2: X-ray crystal structures of [UO(OSi(CH3)3)(thf)Fe2I2(L)] and [UO(OSi(CH3)3)(thf)Zn2I2(L)].

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  1. Amme, M., Wiss, T., Thiele, H., Boulet, P. & Lang, H. Uranium secondary phase formation during anoxic hydrothermal leaching processes of UO2 nuclear fuel. J. Nucl. Mater. 341, 209–223 (2005)

    Article  CAS  ADS  Google Scholar 

  2. Lovley, D. R., Phillips, E. J. P., Gorby, Y. A. & Landa, E. R. Microbial reduction of uranium. Nature 350, 413–416 (1991)

    Article  CAS  ADS  Google Scholar 

  3. Suzuki, Y., Kelly, S. D., Kemner, K. M. & Banfield, J. F. Radionuclide contamination: Nanometre-size products of uranium bioreduction. Nature 419, 134 (2002)

    Article  CAS  ADS  Google Scholar 

  4. Denning, R. G. Electronic structure and bonding in actinyl ions and their analogs. J. Phys. Chem. A 111, 4125–4143 (2007)

    Article  CAS  Google Scholar 

  5. Kühn, F. E., Santos, A. M. & Abrantes, M. Mononuclear organomolybdenum(vi) dioxo complexes: Synthesis, reactivity, and catalytic applications. Chem. Rev. 106, 2455–2475 (2006)

    Article  Google Scholar 

  6. Nam, W. High-valent iron(iv)-oxo complexes of heme and non-heme ligands in oxygenation reactions. Acc. Chem. Res. 40, 522–531 (2007)

    Article  CAS  Google Scholar 

  7. Jin, N., Ibrahim, M., Spiro, T. G. & Groves, J. T. Trans-dioxo manganese(v) porphyrins. J. Am. Chem. Soc. 129, 12416–12417 (2007)

    Article  CAS  Google Scholar 

  8. Limberg, C. The role of radicals in metal-assisted oxygenation reactions. Angew. Chem. Int. Edn Engl. 42, 5932–5954 (2003)

    Article  CAS  Google Scholar 

  9. Mayer, J. M. Hydrogen atom abstraction by metal–oxo complexes: Understanding the analogy with organic radical reactions. Acc. Chem. Res. 31, 441–450 (1998)

    Article  CAS  Google Scholar 

  10. Burdet, F., Pecaut, J. & Mazzanti, M. Isolation of a tetrameric cation-cation complex of pentavalent uranyl. J. Am. Chem. Soc. 128, 16512–16513 (2006)

    Article  CAS  Google Scholar 

  11. Natrajan, L., Burdet, F., Pecaut, J. & Mazzanti, M. Synthesis and structure of a stable pentavalent-uranyl coordination polymer. J. Am. Chem. Soc. 128, 7152–7153 (2006)

    Article  CAS  Google Scholar 

  12. Berthet, J. C., Siffredi, G., Thuery, P. & Ephritikhine, M. Easy access to stable pentavalent uranyl complexes. Chem. Commun.3184–3186 (2006)

  13. Burns, C. J. et al. A trigonal bipyramidal uranyl amido complex: Synthesis and structural characterization of Na(thf)2UO2{N(SiMe3)2}3 . Inorg. Chem. 39, 5464–5468 (2000)

    Article  CAS  Google Scholar 

  14. Sarsfield, M. J., Helliwell, M. & Raftery, J. Distorted equatorial coordination environments and weakening of U = O bonds in uranyl complexes containing NCN and NPN ligands. Inorg. Chem. 43, 3170–3179 (2004)

    Article  CAS  Google Scholar 

  15. Sarsfield, M. J. & Helliwell, M. Extending the chemistry of the uranyl ion: Lewis acid coordination to a U = O oxygen. J. Am. Chem. Soc. 126, 1036–1037 (2004)

    Article  CAS  Google Scholar 

  16. Kannan, S., Vaughn, A. E., Weis, E. M., Barnes, C. L. & Duval, P. B. Anhydrous photochemical uranyl(vi) reduction: Unprecedented retention of equatorial coordination accompanying reversible axial oxo/alkoxide exchange. J. Am. Chem. Soc. 128, 14024–14025 (2006)

    Article  CAS  Google Scholar 

  17. Arnold, P. L., Blake, A. J., Wilson, C. & Love, J. B. Uranyl complexation by a Schiff-base, polypyrrolic macrocycle. Inorg. Chem. 43, 8206–8208 (2004)

    Article  CAS  Google Scholar 

  18. Arnold, P. L., Patel, D., Blake, A. J., Wilson, C. & Love, J. B. Selective oxo functionalization of the uranyl ion with 3d metal cations. J. Am. Chem. Soc. 128, 9610–9611 (2006)

    Article  CAS  Google Scholar 

  19. Docrat, T. I. et al. X-ray absorption spectroscopy of tricarbonatodioxouranate(v), [UO2(CO3)3]5–, in aqueous solution. Inorg. Chem. 38, 1879–1882 (1999)

    Article  CAS  Google Scholar 

  20. Hay, P. J., Martin, R. L. & Schreckenbach, G. Theoretical studies of the properties and solution chemistry of AnO2 2+ and AnO2+ aquo complexes for An = U, Np, and Pu. J. Phys. Chem. A 104, 6259–6270 (2000)

    Article  CAS  Google Scholar 

  21. Wander, M. C. F., Kerisit, S., Rosso, K. M. & Schoonen, M. A. A. Kinetics of triscarbonato uranyl reduction by aqueous ferrous iron: A theoretical study. J. Phys. Chem. A 110, 9691–9701 (2006)

    Article  CAS  Google Scholar 

  22. Zi, G. et al. Preparation and reactions of base-free bis(1,2,4-tri-tert-butylcyclopentadienyl)uranium oxide, Cp'2UO. Organometallics 24, 4251–4264 (2005)

    Article  CAS  Google Scholar 

  23. Cotton, F. A., Marler, D. O. & Schwotzer, W. Dinuclear uranium alkoxides: preparation and structures of KU2(OCMe3)9, U2(OCMe3)9, and U2(OCHMe2)10, containing [U(iv),U(iv)], [U(iv),U(v)], and [U(v),U(v)], respectively. Inorg. Chem. 23, 4211–4215 (1984)

    Article  CAS  Google Scholar 

  24. Donahue, J. P., Goldsmith, C. R., Nadiminti, U. & Holm, R. H. Synthesis, structures, and reactivity of bis(dithiolene)molybdenum(iv,vi) complexes related to the active sites of molybdoenzymes. J. Am. Chem. Soc. 120, 12869–12881 (1998)

    Article  CAS  Google Scholar 

  25. Lorber, C., Donahue, J. P., Goddard, C. A., Nordlander, E. & Holm, R. H. Synthesis, structures, and oxo transfer reactivity of bis(dithiolene)tungsten(iv, vi) complexes related to the active sites of tungstoenzymes. J. Am. Chem. Soc. 120, 8102–8112 (1998)

    Article  CAS  Google Scholar 

  26. O'Grady, E. & Kaltsoyannis, N. On the inverse trans influence. Density functional studies of [MOX5] n (M = Pa, n = 2; M = U, n = 1; M = Np, n = 0; X = F, Cl or Br). J. Chem. Soc., Dalton Trans.1233–1239 (2002)

  27. Costes, J. P., Dahan, F., Dupuis, A. & Laurent, J. P. Nature of the magnetic interaction in the (Cu2+, Ln3+) pairs: An empirical approach based on the comparison between homologous (Cu2+, Ln3+) and (NiLS 2+, Ln3+) complexes. Chem. Eur. J. 4, 1616–1620 (1998)

    Article  CAS  Google Scholar 

  28. Castro-Rodriguez, I., Olsen, K., Gantzel, P. & Meyer, K. Uranium tris-aryloxide derivatives supported by triazacyclononane: engendering U(iii) center with a single pocket for reactivity. J. Am. Chem. Soc. 125, 4565–4571 (2003)

    Article  CAS  Google Scholar 

  29. Rosen, R. K., Andersen, R. A. & Edelstein, N. M. A bimetallic molecule with antiferromagnetic coupling between the uranium centres. J. Am. Chem. Soc. 112, 4588–4590 (1990)

    Article  CAS  Google Scholar 

  30. Reilly, S. D. & Neu, M. P. Pu(vi) hydrolysis: further evidence for a dimeric plutonyl hydroxide and contrasts with U(vi) chemistry. Inorg. Chem. 45, 1839–1846 (2006)

    Article  CAS  Google Scholar 

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We thank the EPSRC (UK), the Royal Society, and the Universities of Edinburgh and Nottingham for support, J. Sanchez-Benitez and P. Anderson of Edinburgh University for help with magnetic susceptibility measurements and chloride analysis respectively, R. Edge and the EPSRC EPR service at the University of Manchester, and D. Leigh for his advice.

Author Contributions D.P. synthesized and characterized the compounds, and solved the crystal structure data. C.W. mounted the crystals, collected the single-crystal X-ray crystallographic data, modelled the disorder components in the structures, and checked the final structure solutions. P.L.A. and J.B.L. generated and managed the project, helped characterize the complexes, analysed the data and wrote the manuscript.

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Correspondence to Polly L. Arnold or Jason B. Love.

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X-ray crystallographic coordinates for 3 and 5 have been deposited at the Cambridge Crystallographic Database, numbers 649987 and 649988 respectively.

Supplementary information

Supplementary Information

This file contains Supplementary Methods, Supplementary Table S1, Supplementary Figures S1-S3 with Legends and additional references. The document describes general experimental procedures, synthetic and characterisation data for compounds 1 to 6, and additional reactivity studies. The Supplementary Figures show FTIR spectroscopic data (1), selected variable temperature magnetic susceptibility data (3), and preliminary EPR data (1) for complexes 1 to 6. Crystallographic details for 3 and 5. (PDF 865 kb)

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Arnold, P., Patel, D., Wilson, C. et al. Reduction and selective oxo group silylation of the uranyl dication. Nature 451, 315–317 (2008).

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