The kinetics of the oxidation of nickel (II) hexaaza and nickel (II) pentaaza macrocycles by the peroxydisulphate anion, S2O82−, were studied in aqueous media. Effect of pH on reaction rate was also studied. The rate increases with increase of S2O82− concentration. Rates are almost independent of acid betweenpH 4 and 2, giving overall a relatively simple second-order rate law followed by oxidation within the ion pair solvent shell. Using rate =+1/2 d[Ni(L)3+]/dt =k[Ni(L)2+][S2O82−], oxidation rate constants were determined.
