Title: Speciation of Copper(II) Complexes in an Ionic Liquid Based on Choline Chloride and in Choline Chloride/Water Mixtures
Authors: De Vreese, Peter
Brooks, Neil
Van Hecke, Kristof
Van Meervelt, Luc
Matthijs, Edward
Binnemans, Koen ×
Van Deun, Rik #
Issue Date: 2012
Publisher: American Chemical Society
Series Title: Inorganic Chemistry vol:51 issue:9 pages:4972-4981
Abstract: A deep-eutectic solvent with the properties of an ionic liquid is formed when choline chloride is mixed with copper(II) chloride dihydrate in a 1:2 molar ratio. EXAFS and UV-vis-near-IR optical absorption spectroscopy have been used to compare the coordination sphere of the cupric ion in this ionic liquid with that of the cupric ion in solutions of 0.1 M of CuCl2 center dot 2H(2)O in solvents with varying molar ratios of choline chloride and water. The EXAFS data show that species with three chloride ions and one water molecule coordinated to the cupric ion as well as species with two chloride molecules and two water molecules coordinated to the cupric ion are present in the ionic liquid. On the other hand, a fully hydrated copper(II) ion is formed in an aqueous solution free of choline chloride, and the tetrachlorocuprate(II) complex forms in aqueous choline chloride solutions with more than 50 wt % of choline chloride. In solutions with between 0 and 50 wt % of choline chloride, mixed chloro aquo complexes occur. Upon standing at room temperature, crystals of CuCl2 center dot 2H(2)O and of Cu(choline)Cl-3 formed in the ionic liquid. Cu(choline)Cl-3 is the first example of a choline cation coordinating to a transition-metal ion. Crystals of [choline](3)[CuCl4][Cl] and of [choline](4)[Cu4Cl10O] were also synthesized from molecular or ionic liquid solvents, and their crystal structures were determined.
ISSN: 0020-1669
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular Design and Synthesis
KU Leuven, Technology Campuses Ghent and Aalst
× corresponding author
# (joint) last author

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