Stability Constants of Lanthanide Complexes with some Structurally Related Organic Ligands

Abstract

The stability constants of the complexes formed between trivalent lanthanide ions and related carboxyphenylhydrazo-B-diketones ligands are repoted, at 30 °C and at constant ionic strength (0.1 KN03), in 75 % dioxane-water. The affinity of different ligands for complexation with lanthanide ions reaches its highest value with ortho-carboxyphenylhydrazo-benzoylacetone, while the lowest affinity is attained in the case of m-carboxyphenylhydrazo-diethyl malonate ligand. The relation between the overall stability constants "Bz" of chelate compounds and both the atomic number of the lanthanide elements and SpKi + pK; of the ligands were investigated.