Effect of reactant solvation on the stability of complexes of silver(I) with 18-crown-6 in ethanol-dimethyl sulfoxide mixtures

The effect of solvation on the stability of the complexes of silver(I) ion with 18-crown-6 ([Ag18C6](+)) upon the change of the solvent composition (EtOH -> (EtOH-DMSO)) was investigated. Gibbs energy of transfer of both silver(I) ion and the macrocyclic ligand employed (18-crown-6) from pure ethanol to ethanol-dimethyl sulfoxide mixtures (DMSO) were obtained by potentiometry and by determining the distribution between two immiscible phases at 25 degrees C, respectively. An increase of DMSO content in the binary mixture results in an increase of the differences in the solvation of the central ion and the complex. This shifts the equilibrium of complex formation towards the formation of products. We show that the relationship between changes in the stability of the coordination compound and changes in the solvate state of the reactants is sufficiently regular to allow for the prediction of changes in the stability of [Ag18C6](+) when a non-aqueous solvent is increasingly replaced by another non-aqueous solvent (C) 2018 Elsevier B.V. All rights reserved.