Title: Coordination environment of [UO2Br4](2-) in ionic liquids and crystal structure of [Bmim](2)[UO2Br4]
Authors: Sornein, Marie-Olga ×
Mendes, Mickael
Cannes, Celine
Le Naour, Claire
Nockemann, Peter
Van Hecke, Kristof
Van Meervelt, Luc
Berthet, Jean-Claude
Hennig, Christoph #
Issue Date: May-2009
Publisher: Pergamon-elsevier science ltd
Series Title: Polyhedron vol:28 issue:7 pages:1281-1286
Abstract: The complex formed by the reaction of the uranyl ion, UO22+, with bromide ions in the ionic liquids 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmiml[Tf2N]) and methyl-tributylammonium bis(trifluoromethylsulfonyl)imide ([MeBu3N][Tf2N]) has been investigated by UV-Vis and U L-III-edge EXAFS spectroscopy and compared to the crystal structure of [Bmim](2)[UO2Br4]. The solid state reveals a classical tetragonal bipyramid geometry for [UO2Br4](2-) with hydrogen bonds between the Bmim(+) and the coordinated bromides. The UV-Vis spectroscopy reveals the quantitative formation of [UO2Br4](2-) when a stoichiometric amount of bromide ions is added to UO2(CF3SO3)(2) in both Tf2N-based ionic liquids. The absorption spectrum also suggests a D-4h symmetry for [UO2Br4](2-) in ionic liquids, as previously observed for the [UO2Cl4](2-) congener. EXAFS analysis supports this conclusion and demonstrates that the [UO2Br4](2-) coordination polyhedron is maintained in the ionic liquids without any coordinating solvent or water molecules. The mean U-O and U-Br distances in the solutions, determined by EXAFS, are, respectively, 1.766(2) and 2.821(2)angstrom in [Bmim][Tf2N], and, respectively, 1.768(2) and 2.827(2) angstrom, in [MeBu3N][Tf2N]. Similar results are obtained in both ionic liquids indicating no significant influence of the ionic liquid cation either on the complexation reaction or on the structure of the uranyl species. (C) 2009 Elsevier Ltd. All rights reserved.
ISSN: 0277-5387
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Biochemistry, Molecular and Structural Biology Section
Chemistry - miscellaneous
× corresponding author
# (joint) last author

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