Der Pharma Chemica
Journal for Medicinal Chemistry, Pharmaceutical Chemistry, Pharmaceutical Sciences and Computational Chemistry


Comparative Solvation Behaviour of Li+ and Na+ ions in Acetonitrile and Nitromethane Binary Mixtures at 298.15 K

Author(s): Hardeep Anand, Narender Singh

Molar conductance of lithium perchlorate (LiClO4), sodium perchlorate (NaClO4), sodium tetraphenylborate (NaBPh4), tetrabutylammonium perchlorate (Bu4NClO4) and tetrabutylammonium tetraphenylborate (Bu4NBPh4) have been measured in the range 0.005-0.2 mol kg-1 in binary mixtures of acetonitrile (AN) and nitromethane ( NM) containing 0, 10, 20, 40, 60, 80 and 100 mol% of NM in AN at 298.15 K. The experimental data of conductance has been analyzed using Shedlovsky method to evaluate limiting molar conductance (Ʌo) of these electrolytes which were further split to obtain limiting ionic conductances (±o) of various ions present in salts. The ionic radii (ri) of ions in solutions were calculated using a modified form of Stoke’s law and were analyzed in the aspects of ion-solvent interactions. The solvated radii (ri) of Li+ and Na+ ions were found to be greater than rest of the ions in the entire solvent composition range which indicates strong solvation of the ions. Bu4N+ and Ph4B- ions were found to show poor solvation due to solvophobic interaction. Solvated radii (ri) values indicate preferential solvation of Li+ and Na+ ions in the intermediate solvent composition range than in pure AN and NM. Li+, however, is found to be better solvated than Na+ in AN+ NM binary mixtures at all compositions.