Kinetics of ternary complex formation with the (nitrilotriacetato)zinc(II) complex: the effect of buffers and pH

Abstract

The temperature-jump relaxation method has been used to measure rate constants for the formation (k_f) and dissociation of ternary complexes between 2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine and 5-nitrosalicylate (2–)(nsa^2–), respectively, and [Zn(nta)(H₂O)]^–[nta = nitrilotriacetate(3–)]; also for proton transfer between Hnsa^–/nsa^2– and various buffers. The effects of pH and buffer on the ternary complexation kinetics have been investigated, and independent equilibrium constants are reported for the formation of several [Zn(nta)B](B = buffer) complexes. Values of k_f for bipy and nsa^2– are similar to those for the corresponding reactions of cobalt(II).