Kinetics and Mechanism of Ligand Substitution Reaction ofTetraamine Macrocyclic Ligand with Tridentate Schiff Basein Copper(II) Complexes

The kinetics of the substitution reaction in the culxcomplexes, where l is the salicylaldehyde semicarbazone tridentateschiff base ligand and x = no3, br and clo4 with n4h2∙2clo4macrocyclic (n4h2∙2clo4 is 5,7,7,12,14,14-hexaniethyl-1,4,8,11-tetraazacyclo tetradeca-4,11-diene dihydrogen perchlorate) were studiedspectrophotometrically in dmf solvent at 25  0.1 °c and an ionicstrength of 0.5 m nano3. the rate constants for ligand exchangereactions were obtained under the pseudo-first-order by measuring theabsorbance changes at 700 nm, where equal to the greatest change inmolar absorptivity between reactants and products. under theseconditions, the overall process is biphasic reaction. therefore, two rateconstants kobs (1) and kobs (2) were obtained. the kobs (1), was fast anddepended on n4h2∙2clo4 concentration and the kobs (2) was notsignificantly affected by the concentration of n4h2∙2clo4 ligand. based on the results, a mechanism for the ligand substitution reaction isproposed.