The Kinetics of the Oxidation of Lysine by μ-Peroxo-Bridged Binuclear Cobalt (III) Complex of Succinimide in Aqueous Hydrochloric Acid Medium

Abstract

Abstract Kinetics of oxidation of Lysine (Lys) and mechanisms by μ-peroxo bis[bis(ethylenediamine)succinimidato-dicobalt(III)]dinitratedihydrate; [LCo(μ-O2)CoL](NO3)2.2H2O (L = suc(en)2), hereafter the complex, was investigated at 420 nm wavelength of maximum absorption of the complex under the conditions hydrogen ions concentration = 1.8 × 10−2 mol dm−3, temperature = 24 ± 1 °C, [LCo(μ-O2)CoL2+] = 1.4 × 10−4 mol dm−3 and ionic strength = 0.5 mol dm−3. First order in [LCo(μ-O2)CoL2+] and [Lys] were obtained but inverse first order in [H+]. The proposed overall rate equation is as shown: Rate = ( k 1 k 2 + K 1 k 3 k 4 1 [ H + ] ) [ LCo ( μ O 2 ) CoL 2 + ] [ Lys ] $$Rate = ({{k_1 } \over {k_2 }} + {{K_1 k_3 } \over {k_4 }}{1 \over {[H^ + ]}})[LCo(\mu O_2 )CoL^{2 + } ][Lys]$$ Rate of the reaction decreases when hydrogen ions concentration increase and exhibited converse effect with increase in concentration of ionic strength from 0.1 – 1.3 mol dm−3. Added cations and anions affected the reaction rate and the Michaelis-Menten plot passed through the origin indicating no absence of intermediate complex in the electron transfer processes. Putting all the results obtained together, the most probable reaction mechanism is in favour of outer-sphere and an appropriate rate law is established using steady state approximation.