Nuclear magnetic resonance studies of preferential solvation. Part 6.—Application of Blander's coordinated cluster theory to the methanol–water solvent system

Abstract

A statistical-mechanical approach, the coordinated cluster theory (CCT), originally developed by Blander et al. for molten salts, has been applied to the solvation of ions in binary mixed solvents. The relations between CCT and the stepwise-equilibria model approach of Covington and Newman have been highlighted. The non-ideal mixing of solvent molecules in the solvation shell incorporated into CCT shows that partial compensation of non-ideality effects between bulk solvent and solvation shell occurs, as intuitively expected. The theory is applied to the methanol–water solvent system to compare electrochemically derived free energies of transfer with the sum of single-ion values calculated from spectroscopic studies and Born theory electrostatic contributions.