Abstract

Kinetics and mechanism of oxidation of the ternary complex of cobalt(II) involving N-(2-acetamido) iminodiacetic acid and malonate by periodate in acetate medium

Author(s): Hassan A.Ewais, Mohamed R.Shehata, Mohammed A.Nagdy3, Ahmed A.Abdel-Khalek

The kinetics of the oxidation of [CoII(ADA)(M)(H2O)2]2- (ADA = N-(2- acetamido)iminodiacetic andM=Malonate) by periodate in acetatemedium have been investigated spectrophotometrically at 580 nmunder pseudo first order condition by taking large excess of oxidant (IO4 -) over the 15.0-35.0ï‚°C range at pH = 4.99 and I = 0.50M. The kinetics in acetatemediumobeyed the rate law: d[CoIII]/dt = (k2 + k3[CH3CO2 -])[CoII(ADA)(M)(H2O)2]2-[IO4 -]. The initial cobalt(III) products were formed and slowly converted to final products, fitting an inner-sphere mechanism. The enthalpy and the entropy of the activation were measured using the transition state theory equation