The solute and aquaion structure in a concentrated aqueous solution of copper(II) chloride

Neutron diffraction experiments were carried out on isotopically labelled copper chloride (CuCl 2 ) salt in a 4 molal aqueous solution. The first- and second-order isotopic difference methods were used to obtain structural information on the hydration structure of the Cu 2+ and Cl - ions and to calculate the pair distribution functions g CuCl (r) and g ClCl (r) The results confirm the highly distorted nearest-neighbour coordination of Cu 2+ , and give direct evidence that Cu-Cl contacts exist over a range 2.3<or=r (AA)<or=3.5. Analysis of g ClCl (r) gives consistent information with that of g CuCl (r) and shows that direct contacts also exist between Cl - ions, over the range 2.8