Microsolvatación de cationes en disolución. Desarrollo del modelo de ion hidratado intercambiable y su aplicación a la química de cationes radiactivos

Abstract

Aqua ions, of general formula [M(H2O)n ] m+, are the most common structures adopted by metal cations, Mm+, when chemical conditions inhibit the formation of hydrolyzed and polymerized derivatives. 1 The implicit net charge, m+, and the polar and polarizable character of water lead to electrostatic effects so strong that the perturbation exerted on the solvent goes beyond the formation of these coordination complexes or aqua ions, defining different solvation shells which surround the central metal cation. This picture of the hydration structure was firstly proposed by Frank and Evans and is named as the concentric shells model 2 (see Fig. 1). In a global sense the formation of the aqua ion is not enough to describe the behavior of an ion in solution, and the condensed medium effect has to be taken into account through different solvation shells and/or the bulk.