Solvation of monatomic cations by polar solvents and the mean spherical approximation

The Gibbs salvation free energy Delta G(solv)(i), for monatomic cations of alkali metals and alkaline earth metals with a charge z(i) in six protic and ten aprotic dipolar solvents were analyzed in terms of the simplified Fawcett's model based on the mean spherical approximation (MSA). Excellent linear relationships between -Z(i)(2)/Delta G(solv)(i) and the ion radius r(i) were found resulting in the determination of f(dd) and delta(s) correction terms from slopes and intercepts, respectively. It was shown that the f(dd) term increases with a dimensionless parameter describing dipole-dipole interactions and the delta(s) term decreases with the empirical solvent parameter beta describing the hydrogen-bond acceptor basicity. The role of these terms and their mutual relations are discussed. (C) 2014 Elsevier B.V. All rights reserved.