Speciation of Rare‐Earth Metal Complexes in Ionic Liquids: A Multiple‐Technique Approach |
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| Authors: | Peter Nockemann Dr. Ben Thijs Dr. Kyra Lunstroot Dr. Tatjana N. Parac‐Vogt Prof. Dr. Christiane Görller‐Walrand Prof. Dr. Koen Binnemans Prof. Dr. Kristof Van Hecke Dr. Luc Van Meervelt Prof. Dr. Sergey Nikitenko John Daniels Dr. Christoph Hennig Dr. Rik Van Deun Prof. Dr. |
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| Affiliation: | 1. Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F bus 2404, 3001 Leuven (Belgium), Fax: (+32)?16‐327992;2. Netherlands Organization for Scientific Research (NWO), DUBBLE@ESRF, 6 rue Jules Horowitz, 38043 Grenoble CEDEX (France);3. High Energy Scattering Beamline ID15, European Synchrotron Radiation Facility, 6 rue Jules Horowitz, 38043 Grenoble CEDEX (France);4. Institute of Radiochemistry, Forschungszentrum Dresden‐Rossendorf, P.O. Box 510119, 01314 Dresden (Germany);5. Department of Inorganic and Physical Chemistry, Universiteit Gent, Krijgslaan 281 Building S3, 9000 Gent (Belgium), Fax: (+32)?9‐264‐49‐83 |
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| Abstract: | The dissolution process of metal complexes in ionic liquids was investigated by a multiple‐technique approach to reveal the solvate species of the metal in solution. The task‐specific ionic liquid betainium bis(trifluoromethylsulfonyl)imide ([Hbet][Tf2N]) is able to dissolve stoichiometric amounts of the oxides of the rare‐earth elements. The crystal structures of the compounds [Eu2(bet)8(H2O)4][Tf2N]6, [Eu2(bet)8(H2O)2][Tf2N]6?2H2O, and [Y2(bet)6(H2O)4][Tf2N]6 were found to consist of dimers. These rare‐earth complexes are well soluble in the ionic liquids [Hbet][Tf2N] and [C4mim][Tf2N] (C4mim=1‐butyl‐3‐methylimidazolium). The speciation of the metal complexes after dissolution in these ionic liquids was investigated by luminescence spectroscopy, 1H, 13C, and 89Y NMR spectroscopy, and by the synchrotron techniques EXAFS (extended X‐ray absorption fine structure) and HEXS (high‐energy X‐ray scattering). The combination of these complementary analytical techniques reveals that the cationic dimers decompose into monomers after dissolution of the complexes in the ionic liquids. Deeper insight into the solution processes of metal compounds is desirable for applications of ionic liquids in the field of electrochemistry, catalysis, and materials chemistry. |
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| Keywords: | EXAFS spectroscopy HEXS (high‐energy X‐ray scattering) ionic liquids rare earths UV/Vis spectroscopy |
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