Chelates of certain rare earths with mixed ligands. La(3), Pr(3), Nd(3)-N-hydroxyethylethylenediamine-N,N1,N2-triacetic acid-hydroxy acids

Determined are the constants of complex formation with mixed metal ligands [La(3), Pr(3), Nd(3)]-N-oxiethyl-ethylendiamine-N,N1,N2-triacetic acid-ligand (glycolic, malic, lactic acids). The values of complex formation constants with mixed ligands are lower than that of binar complex formation (1:1) constants which can be accounted for taking into consideration electrostatic attraction and basicity of the participating ligands. For all the investigated systems the complex formation constants with mixed ligands are arranged in a raw: La(3)<Pr(3)<Nd(3)