Coordination numbers of ions, interparticle distances, and types of ion pairs in nickel chloride aqueous solutions are determined in a wide range of concentrations under standard conditions using a model approach to X-ray diffraction data. It is established that the structure of the saturated nickel chloride solution is determined by the set of contact ion pairs and independently hydrated ions. As a result of dilution, ion pairs get broken, while the number of solvent molecules in the immediate environment of ions increases. The Ni2+ coordination number in dilute solutions increases up to six. The number of water molecules in the second coordination spheres of cations and in the immediate environment of anions increases with decreasing concentration.
Смирнов et al. (Wed,) studied this question.