DISSOCIATION KINETICS OF TMDTA AND TMEDTA COMPLEXES OF LANTHANIDES

The dissociation kinetics of TMDTA (trimethylenedinitrilotetraacetic acid) and TMEDTA (tetramethyl-enedinitrilotetraacetic acid) complexes of Ce(111) Eu(1II) and Yb(111) ions have been studied in aqueous solution using Cu(II) ions as the scavenger in acetate buffer (1 = 0.1 M) at 25°C. All the complexes exhibit acid-dependent and acid-independent pathways in a manner similar to LnDCTA- complexes. The buffer concentration dependence of the rate of dissociation has also been investigated. The rates of dissociation of LnTMDTA- and LnTMEDTA- complexes are much faster than those of LnEDTA- complexes. The chelate ring size effect is discussed by comparing the rate constants to those of analogous EDTA and DCTA systems. © 1991, Taylor & Francis Group, LLC. All rights reserved.