Phase and coordination equilibria in three-component systems of the type MBr2+ pyridine + chlorobenzene (M = Mn, Co, Ni, Cu and Zn)

Abstract

Solubility isotherms for MnBr₂, CoBr₂, NiBr₂, CuBr₂ and ZnBr₂ in pyridine + chlorobenzene mixtures of varying composition have been determined at 20 and 30°C. Changes in the visible spectra of CoBr₂, NiBr₂ and CuBr₂ with varying solvent composition have been followed. The results are analysed in terms of the nature of the solution complexes, their solvent-dependent activity coefficients and relative stabilities. The activity coefficients are found to be different functions of solvent composition for the [MBr₂py₂] and [MBr₂py₄] types of complexes but to a good approximation are independent of the nature of the central metal atom.