Structure and reactivity of ion hydration complexes in solution

Hydration complexes, long an object of study in the coordination chemistry field, can now be studied more directly by new and powerful methods. Among the new experimental methods are the refined neutron scattering methods developed by J. E. Enderby, G. Neilson and co-workers. Another is the study of ion-solvent clusters in molecular beams, especially by spectroscopic techniques. Some important new theoretical studies begin with calculating the Born-Oppenheimer potential surfaces for very small ion-water clusters. Then one of the available statistical mechanical techniques is applied to generate solvent-averaged ion-ion pair potentials from which measurable equilibrium solution properties can be calculated. In another new development, the same solvent-averaged models are dressed with bare ionic self diffusion coefficients and with the ion-ion hydrodynamic interactions. From such models one can calculate some of the solution transport coefficients for comparison with real systems. Illustrations of both consistencies and contradictions are found.