Aminocarboxylate Complexes Research Articles

ΔH – ΔS Relationships in Metal Complex Formation

A HIGHLY significant correlation between reaction enthalpies and entropies is often observed in different equilibrium and rate processes. Lumry and Rajender1 have suggested the existence of two forms of water and one of the important arguments for their hypothesis is a rough constancy of the slope (Tc) in plots of ΔH against ΔS for a wide variety of reaction systems, most Tc values being between 270 and 320 K. The aim of this article is to point out some aspects of solvation in complex formation in solution that may lead to an enthalpy-entropy “compensation” in other words, the enthalpy and entropy changes compensate each other, thus limiting the change in free enthalpy. Our approach is, in a sense, complementary to the Lumry-Rajender hypothesis, neither supporting nor contradicting it. We have limited our discussion to alkaline earth and lanthanide aminocarboxylate complexes.

Hydration and structure of some copper(II) ethylenediaminetetra-acetate and aminocarboxylate complexes in aqueous solution

Hydration and structure of some copper(II) ethylenediaminetetra-acetate and aminocarboxylate complexes in aqueous solution