Activity coefficients of single complexes and coordination equilibria in three-component systems of the type MX2+ solvent + diluent. Systems involving CoCl2, ZnCl2, CuCl2, pyridine, benzene, chlorobenzene and o-dichlorobenzene

Abstract

Solubility isotherms for CoCl₂, ZnCl₂ and CuCl₂ in mixtures of pyridine with benzene and o-dichlorobenzene, and the visible absorption spectra of the solutions containing CoCl₂, have been determined. The results are analysed in terms of the nature of complexes existing in the liquid phases, their activity coefficients and the equilibrium constant of the reaction [CoCl₂py₄]⇌[CoCl₂py₂]+ 2py. Taking into account the regularities controlling the activity coefficients, the single complex existing in solutions of CuCl₂ is shown to be pentacoordinate [CuCl₂py₃].