Collect. Czech. Chem. Commun. 1994, 59, 1077-1085

Kinetics and Mechanism of Ligand Substitutionin Triglycinatovanadium(III) by EDTA and NTA in Aqueous Solutions

Yasuhisa Ikedaa, Refat M. Hassanb, Moustafa M. Abd El-Fattahc, Yul Y. Parkc and Hiroshi Tomiyasuc

a Institute of Research and Innovation, Nuclear Chemistry and Chemical Engineering Center, 1301 Takada, Kashiwa, Chiba 277, Japan
b Chemistry Department, Faculty of Science, Assiut University, Assiut, Egypt 71516
c Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, O-Okayama, Meguro-Ku, Tokyo 152, Japan


The kinetics of ligand substitution reactions in triglycinatovanadium(III) by EDTA and NTA as multidentate ligands were investigated at a constant ionic strength of 2.5 mol dm-3 spectrophotometrically. The substitutions were second-order reactions, first order in both reactants. Their rate could be expressed in the form r = k [V(gly)3] [EDTA(NTA)] where k = 2.62 .10-2 and 6.96 .10-2 mol-1 dm3 s-1 at 25 °C for EDTA and NTA, respectively. The results obtained at different pH indicated that [H2edta]2- and [Hnta]2- ions were the most reactive species in the substitution. Kinetic parameters have been evaluated and a tentative mechanism of the reaction has been proposed.