The pervasive solvent-separated sodium chloride ion pair in water-DMSO mixtures

Abstract

Sodium chloride exists as a contact ion pair (CIP) as well as a solventseparated ion pair (SSIP) in its solutions in water and in dimethyl sulphoxide (DMSO). In a mixture of these two solvents, the CIP is not formed in the two mixture compositions with χDMSO = 0'35 and 0-21 and the ions stay as the SSIP near an interionic distance of 5-0 Å. This has been shown by constructing the ion-ion potentials of mean force and by following the ion-pair trajectories initiated at various initial ion-pair separations in the two solvent mixtures. © Indian Academy of Sciences.