Potentiometric study of the kinetics and equilibria of formation of chloroglycinate palladium(II) complexes from bis-glycinato palladium(II) complexes

摘要

The equilibria and kinetics of the reaction of Pd(gly)(2) complexes with hydrogen ions and chloride ions has been studied by a potentiometric method. The underlying idea of the method is the measurement of solution pH as a function of reaction time t using a glass electrode. The solutions used had the following initial compositions: xM Pd(gly)(2), xM Hgly, and 1 M NaCl with x = 1 x 10(-4), 5 x 10(-4), and 1 x 10(-3); initial pH(0) was from similar to 3.5 to similar to 4.4. The experimentally determined pH versus t dependences and the rate equation for a pseudo-second-order reaction were used to determine the equilibrium constant of formation of Pd(gly)(Hgly)Cl complexes from Pd(gly)(2) complexes and the observed rate constant for this reaction, k (obs). The dependence of k (obs) on the pH of the acid solutions studied was assigned to a change in the sequence of the reactions of addition of a hydrogen ion and a chloride ion to the complex Pd(gly)(2).