Section 56
Chapter 55,868

Speciation of uranyl complexes in ionic liquids by optical spectroscopy

Nockemann, P.; Servaes, K.; Van Deun, R.; Van Hecke, K.; Van Meervelt, L.; Binnemans, K.; Görller-Walrand, C.

Inorganic Chemistry 46(26): 11335-11344


ISSN/ISBN: 0020-1669
PMID: 18044883
DOI: 10.1021/ic701752j
Accession: 055867617

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Uranyl complexes dissolved in room-temperature ionic liquids have diagnostic absorption and emission spectra which reflect the molecular symmetry and geometry. In particular, the characteristic vibrational fine structure of the absorption spectra allows identification of the molecular symmetry of a uranyl complex. The concept of speciation of uranyl complexes is illustrated for the hydrated uranyl ion, the tetrachloro complex [UO2Cl4]2-, the trinitrato complex [UO2(NO3)3]-, the triacetato complex [UO2(CH3COO)3]-, and the crown ether complex [UO2(18-crown-6)]2+ in imidazolium and pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids. The competition between 18-crown-6 and small inorganic ligands for coordination to the uranyl ion was investigated. The crystal structures of the hydrolysis product [(UO2)2(mu2-OH)2(H2O)6] [UO2Br4](18-crown-6)4 and imidazolium salt [C6mim]2[UO2Br4] are described.

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