Speciation of chloroindate(III) ionic liquids.

A range of chloroindate(iii) ionic liquid systems was prepared by mixing of 1-alkyl-3-methylimidazolium chloride with indium(iii) chloride in various ratios, expressed as the mol fraction of indium(iii) chloride, chi(InCl(3)). For chi(InCl(3))</= 0.50, the products were liquids, whereas for chi(InCl(3)) > 0.50, the products were biphasic (suspensions of a solid in an ionic liquid). Speciation of these chloroindate(iii) systems was carried out using a wide range of techniques: differential scanning calorimetry (DSC), polarised optical microscopy (POM), liquid-state and solid-state (115)In NMR spectroscopy, X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS). Ionic liquids prepared using an excess of the organic chloride (chi(InCl(3)) < 0.5) contained InCl(6), InCl(5) and InCl(4) anions, in proportions dependent on the chi(InCl(3)) value. Equimolar mixtures yielded single compounds: 1-alkyl-3-methylimidazolium tetrachloroindates(iii). Systems containing an excess of indium(iii) chloride (chi(InCl(3)) > 0.5) contained indium(iii) chloride powder suspended in a neutral tetrachloroindate ionic liquid.