Substitution Reactions of Lead(II) Complexes of 3, 6-Dioxaoctane-1, 8-diamine-N, N, N', N'-tetraacetate with Copper(II), Cadmium(II) and Nickel(II) Ions

Abstract

Kinetics of the substitution reactions of lead On complexes of 3, 6-dioxaoctane-1, 8-diamine N, N', N'-tetraacetate with copper(II), cadmium (11) and nickel (II) ions were studied at 20 ° C in the pH range of 3.0-4.8 and at an ionic strength of O.1, in the presence of excess lead(I) ions ((0.05-1.0) x 10-3mol. dm^-3). The reverse reactions were kinetically studied in the presence of excess copper(I), cadmium(II) and nickel(I) ions (1.0 x 10-9-1.0 x 10-1mo'. dm^-9), respectively, in a similar way to the above study.
The initial rate equations for the forward and reverse reactions were obtained from the measurement of change in absorbance at wavelengths of 260 and 235 nm by stoppe-flow method. The rate constants for the formation of CuHX-, CdHX- and NiHX- where X4- denotes the completely-deprotonated ligand anion, were estimated to be (9.6 0.5) x 109, (3.4 0.2) x 109 and (2.6 0.7) X 105dm3. mol-lec-, respectively.