Speciation of Rare-Earth Metal Complexes in Ionic Liquids: A Multiple-Technique Approach

Autor: Ben Thijs, Christiane Görller-Walrand, John E. Daniels, Peter Nockemann, Koen Binnemans, Christoph Hennig, Sergey I. Nikitenko, Kristof Van Hecke, Rik Van Deun, Tatjana N. Parac-Vogt, Luc Van Meervelt, Kyra Lunstroot
Rok vydání: 2009
Předmět:
Zdroj: Chemistry-A European Journal 15(2009), 1449-1461
ISSN: 1521-3765
0947-6539
DOI: 10.1002/chem.200801418
Popis: 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][Tf(2)N]) is able to dissolve stoichiometric amounts of the oxides of the rare-earth elements. The crystal structures of the compounds [Eu(2)(bet)(8)(H(2)O)(4)][Tf(2)N](6), [Eu(2)(bet)(8)(H(2)O)(2)][Tf(2)N](6) x 2 H(2)O, and [Y(2)(bet)(6)(H(2)O)(4)][Tf(2)N](6) were found to consist of dimers. These rare-earth complexes are well soluble in the ionic liquids [Hbet][Tf(2)N] and [C(4)mim][Tf(2)N] (C(4)mim = 1-butyl-3-methylimidazolium). The speciation of the metal complexes after dissolution in these ionic liquids was investigated by luminescence spectroscopy, (1)H, (13)C, and (89)Y 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.
Databáze: OpenAIRE
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