Ion Association and Solvation Behaviour of Nickel(II) Complexes in Binary Mixtures of DMSO-H2O at Different Temperatures

Abstract

Electrical conductance and solvation behaviour of [Ni(HL)(bipy)(H2O)](NO3)(ClO4)(H2O) and [Ni(HL)(dien)](ClO4)2(H2O), where HL = 2-[(1)-pyridin-2-ylmethylidene]benzohydrazide in various compositions (0-100 %) of H2O + DMSO in the temperature range 288.15 to 308.15 K have been studied by conductance measurement. The conductance data have been analyzed by Shedlovsky equation. The limiting molar conductance Λο has been decreased with the increase in the percentage of DMSO in the mixed solvent. This is due to increase in solvent-solvent interaction and increase in the dielectric constant. Owing to their high viscosity and molecular measurements of DMSO in water, lower specific conductance has been observed in H2O + DMSO. The KA values have been increased on increasing the temperature and increasing the percentage of DMSO in the mixed solvent presenting endothermic character of ionic association in this system. Activation energy of the rate process and related thermodynamic parameters have been evaluated and reported. Applying viscosity of the solvent/solvent mixture, Walden product Λoηo and effective radius r (Å) have been obtained and discussed. The results have been interpreted in terms of ion-solvent interactions and solvent-solvent interactions.