Kinetics of ternary complex formation between nickel(II) species and pyridine-2-azo-p-dimethylaniline

Abstract

The stopped-flow and temperature-jump relaxation methods have been used to measure the rate constants and activation parameters for the formation and the dissociation of the 1 : 1 complex between nickel(II) and pyridine-2-azo-p-dimethylaniline (PADA) and of the ternary complexes between PADA and the nickel(II)-polytriphosphate, -iminodiacetate, -N-methyliminodiacetate, -nitrilotriacetate, -diethylenetriamine, -triethylenetetramine and -2,2′,2″-triaminotriethylamine complexes. The rate constants at 25°C for the reaction between the Ni(II) complex of 1,4,8,11-tetra-azaundecane(2,3,2-tet) and NH₃ are also reported. The series provides further evidence that the number of binding nitrogen atoms on the first ligand has a larger influence on ternary complex formation than its charge.