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A new macrocyclic ligand 1,15,18-triaza-3,4;12,13-dibenzo-5,8,11-cycloeicosane (NdienOdienH4 = N3O3) has been synthesized and identified by element analysis, NMR and IR spectrophotometry. Stepwise protonation constants of ligand are determined by potentiometry in 95% methanol solution(I = 0.1 mol dm-3, Me4NCl). log K1;log K2;log K3 = 9.1;8.1;3.6.The kinetics of the acid-promoted dissociation reactions of complex cations of nickel(Ⅱ) and copper(Ⅲ) with NdienOdien and NdienOen macrocyclic ligands having, respectively, 17 and 20 ring members, have been studied spectrophotometrically in HClO4 NaClO4 aqueous solutions. From the temperature effect on kinetic constant (kobs), the parameters of activation(ΔH≠, ΔS≠) of dissociation reaction for ML2+ with H+ ion have been determined. We have proposed the possible mechanism of the reaction from the data obtained.
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