Structural studies of lanthanide (III) complexes with oxydiacetic acid and iminodiacetic acid in aqueous solution by EXAFS.

The local structure of the trivalent lanthanide (Ln(III)) complexes with oxydiacetic acid (ODA) and iminodiacetic acid (IDA) in aqueous solution was investigated by EXAFS spectroscopy. The coordination number and the bond distance were obtained by the detailed EXAFS analysis. The coordination number of Ln(III) in both the Ln-ODA and -IDA systems decreases from nine for lighter Ln(III) to eight for heavier Ln(III). The bond distances of ether O atoms from Ln(III) in the Ln(ODA)(3)3- complexes are shorter than those of N atoms in the Ln(IDA)(3)3- ones.