Kinetics of Ternary Complex- Formation Between Cobalt (II)sPECIES AND 5-Nitrosalicylic Acid - the Effect of Charge

The temperature-jump relaxation method has been used to measure rate constants and activation parameters for the formation and dissociation of a 1:1 complex between cobalt(II) and 5-nitrosalicylate(2-) (nsa(2-)), and of ternary complexes between nsa(2-) and cobalt(II)-nitrilotriacetate,-ethylenediamine N,N-diacetate,-ethylenediamine-N,N'-diacetate, and -triethylenetetramine; also rate constants for the formation and dissociation of ternary complexes between nsa and cobalt(II)-polytriphosphate,-iminodiacetate and -diethylenetriamine. Independently determined equilibrium constants are reported for [Co(nsa)] and for the ternary complexes involving polytriphosphate, nitrilotriacetate, ethylenediamine-N,N-diacetate and N,N'-diacetate. The rate parameters are compared with those for the corresponding nickel(II) reactions and for the corresponding reactions of both metals with the neutral ligand N,N-dimethyl (p-pyridin-2-ylazo)aniline. The results for nsa re only partly explicable in terms of the Fuoss equation.