ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

New complexons. XXXI. Chelates of ethylenediamine-N,N'-dimalonic, ethylenediamine-N,N'-disuccinic, and ethylenediamine-N,N'-α,α'-diglutaric) acids with lanthanide(III) ions

E. Dvořáková, Z. Pikulíková, and J. Majer

Pharm. Fac., Komensky Univ., Bratislava

Abstract: Complexes of the title acids (EDDM, EDDS, and EDDG, resp.) with the lanthanide ions La(III) to Lu(III) except for Pm were studied in aq. solns. by potentiometry and paper electrophoresis. Neutralization curves and the 'tren' methods were used to evaluate the stability consts. of complexes for I = 0.10 (KNO₃) and t = 20°. Paper electrophoresis was employed to study the charge of complex particles and to confirm the compn. of complexes. Formation of 1:1 ML complexes was obsd.; with excess complexing agent in neutral or mild alkaline pH region, ML₂ complexes were formed. The formation of ML₂ is most marked with EDDM yielding the ML₂ complexes with all lanthanides. On the other hand, EDDS and EDDG form ML₂ complexes only with heavier lanthanides, esp. from Ho to Lu, whereas in the case of the 1st 4 (La-Nd) only 1:1 complexes were formed under the exptl. conditions. The formation of higher ML₂ complex is related to the lower donor ability of the complexons and the possibility of higher coordination no. of lanthanides. The formation of sparingly sol. compds. in mild acidic medium is characteristic of EDDM reacting with lanthanides. In the case of La, a compd. of compn. H₆La₂L₃·8H₂O was isolated.

Full paper in Portable Document Format: 291a44.pdf (in German)

Chemical Papers 29 (1) 44–51 (1975)