Abstract
The kinetics of the reaction between 1,4,8,11‐tetraazacyclotetradecane (Cy) and Ni^2+^ in the presence of series of ligands L = fluoride, acetate, glycolate, oxalate, malonate, succinate, methanetriacetate, 1,3,5‐cyclohexanetriacetate, tricarballylate, picolinate, glycinate, iminodiacetate, nitrilotriacetate. N,N′ ‐ethylenediiminodiacetate, ammonia, pyridine, ethylenediamine, 1,3‐propanediamine and diethylenetriamine were studied by pH‐static and spectrophotometric methods at 25° and I = 0.5. By analysis of the log k/log [L] and/or log k/pH profiles the resolved bimolecular rate constants K (Table 3) were determined using a non‐linear least‐square fitting procedure. Practically for all systems the rate constant K, describing the reaction between the 1:1 Ni^2+^ complex and the monoprotonated form of the macrocycle, was obtained. In some cases, however, also K and K were found. Since the experimental conditions were choosen so that NiL was mainly formed, the reactivity of NiL~2~ was generally not measurable. The effect of the number of coordinated donor groups in NiL and of the charge of NiL on K is discussed. Both effects seem to indicate that for the reaction between NiL and CyH^+^ first bond formation is not the rate‐determining step.