Recent aspects of single ion transfer properties
Gibbs energies, entropies and enthalpies of transfer for several cations and anions from acetonitrile into various solvents formed the basis for investigations on general trends in the interactions of solvent molecules with positively and negatively charged ions. Gibbs energies of transfer for Na+, K+, Rb+, Cs+, Cuff T1+ and Ag+ obtained from different assumptions, experimental techniques and research groups together with a large number of recen ly pu lishe energies of transfer for Li+, Ba2+, Cu", Zn9+, Cd9+,GiHbgb5+ and Pb2+ based on the bis (bipheny1)chromium assumption - were employed to study the interactions of hard and soft donor solvents with hard, soft and borderline cations. Solvent effects on anions were deduced from the Gibbs energies of transfer for Cl', Br-, I- and SCN-. Parameters proposed to account for hard and soft donor properties or for acceptor properties of the solvents were compared with the Gibbs energies of transfer. Parameters representing hard donor properties of solvents correlated with Gibbs energies of transfers for cations into hard solvents, but transfer properties of soft and borderline cations into soft solvents called for a different solvent parameter. The Gibbs energies of transfer for anions related to such solvent parameters that characterized acceptor properties. The solvent induced changes in the Gibbs energies of transfer of hard and soft cations as well as the respective data for anions were explained within the framework of a donor-acceptor model of ion-solvent interactions, including the principle of hard and soft acids and bases. The current status on enthalpies and entropies of transfer is discussed.