Thermochemical properties of RE (Gly)4 Im (ClO4) 3 2H2O (RE = La, Pr, Nd, Sm, Eu)

Abstract

AbstractThe enthalpies of solution in water for five new light rare earth ternary complexes RE(Gly)4Im(ClO4)3 2H2O (RE = La, Pr, Nd, Sm, Eu; Gly‐glycine; Im‐imidazole) were measured by means of a Calvet microcalorimeter. The empirical formula of enthalpy of solution (ΔsolH), relative apparent molar enthalpy (πLi), relative partial molar enthalpy (Li) and enthalpy of dilution (ΔdllH1,2) were drawn up by the data of enthalpies of solution of these complexes. From three plots of the values of standard enthalpy of solution Δsol Hϕ, πLi, Li) versus the values of ionic radius (r) of the light rare earth elements, the grouping effect of lanthanide was observed, showing that the coordination bond between rare earth ion and ligand possesses a certain extent of the property of a covalent bond. The standard enthalpies of solution in water of similar complexes, Ce(Gly)4Im(ClO4)3.2H2O were estimated according to the plot of ΔsolHϕ, versus r.