Proton and 13C nuclear magnetic resonance studies of some yttrium and lanthanum complexes in aqueous solutions

Abstract

Distinct proton and 13C resonance patterns are observed for saturated solutions of complexes of the formula KLa(edta)·8H 2O, K 2LnOH(edta)·4H 2O and K 3LnO 2(edta)·H 2 O (Ln  Y, La; edta  ethylenediaminetetraacetate) in deuterium oxide and are dependent upon the type of complex in the solid state. Proton and 13C chemical shifts are metal sensitive. The 13C spectra generally show three sharp single lines resulting from the resonance of carbon in the carboxylato, methylene-acetato and methylene backbone groups respectively. In comparison with the non-coordinated H 2edta 2− ion, all 13C chemical shifts are observed at higher frequencies for metal-coordinated edta, and carbons from both kinds of methylene groups display the metal- and the complex-type sensitivity. The proton spectra of yttrium complexes indicate that the presence of a peroxo group in the edta ligand sphere affects the lability of the Y—N bond in aqueous solution.