Abstract
The kinetics of oxidation of the ternary complexes [Co-II(ADA)(L)(H2O)](2-) (ADA = N-(2-acetamido)iminodiacetate, L = maleic acid) by periodate has been investigated spectrophotometrically in aqueous medium over 30-50 degrees C range, pH 3.72-4.99 and I=0.2 mol dm(-3). The reaction was carried out under pseudo-first order conditions by using a tenfold excess of [IO4-] over [Coll(ADA)(L)(H2O)(2-). The kinetics of oxidation of [Co-II(ADA)(L)(H2O)](2-) obeyed the rate law:
d[Co-III]/dt = [Co-II(ADA)(L)(H2O)(2-)] [H5IO6] {k(4)K(5) + (k(5)K(6)K(2)/[H+])}.
The system was studied at different concentrations of acetate ion over a temperatures range (25-40)degrees C and the kinetics of oxidation of [Co-II(ADA)(L)(H2O)](2-)obeyed the rate law:
d[Co-III]/dt ={k(8)K(8) + k(9)K(7)K(9)[CH3CO2-} [Co-II(ADA)(L)(H2O)(2-)] [IO4-.
The initial Co(III) products were slowly converted to the final products, fitting an inner-sphere mechanism. Thermodynamic activation parameters were calculated using the transition state theory equation.