Structure and Thermodynamics of Lanthanide and Actinide Complexes in Solution

Abstract

Several questions of importance in the study of lanthanide and actinide coordination compounds are revieed. There is considerable evidence that in aqueous solution the primary coordination number is nine for the ions La(m) through Nd(III) and eight for the ions heavier than Gd(III). hile it seems that some degree of covalency exists in the metal-ligand bonding a model of electrostatic bonding seems satisfactory for explaining the structure and formation of the complexes. The dehydration of the lanthanide ions upon complexation largely determines the enthalpy and entropy data. Hoever, there seems to be a compensation effect in the hydration parts of those terms such that the free energy changes seem to reflect the metal—ligand reaction unobscured by hydration factors. A number of individual inorganic and organic ligand systems are revieed from these viepoints. © 1971, Walter de Gruyter. All rights reserved.