Structure of concentrated aqueous solutions of indium chloride and bromide. Modelling of the structure of electrolyte solutions

Concentrated aqueous solutions of indium bromide (3.06 mol dm^-3 ) and chloride (3.22 mol dm^-3 ) were investigated by x-ray diffraction. In order to interpret the profile of the diffraction patterns, the existence of positional correlations between cation complexes and between cation complexes and (free) anions extending to distances beyond 7 Å is discussed. These complexes are constituted by the coordination around the indium cation of two anions, bromide or chloride, and five (six? for the bromide solutions) water molecules. The structure of these complexes was previously investigated by Raman spectroscopy and by EXAFS. Results of these and of other investigations are compared with those recently obtained.