Reaction of N, N1-phenylenebis(salicyalideneiminato)cobalt(III) and l-cysteine in mixed aqueous medium: kinetics and mechanism

Abstract

The redox kinetics involving the reaction of N, N′-phenylenebis(salicyalideneiminato)cobalt(III) ([CoSalophen]+) and l-cysteine (LSH) was studied using pseudo-first order approach under the following conditions, [H+] = 1.0 × 10−3 mol/dm3, μ = 0.1 C2 mol/dm3 (NaCl), λmax = 470 nm and T = 27 ± 1 °C in DMSO: H2O; 1:4 v: v medium. The redox reaction was 1st order in both [CoSalophen+] and [LSH], with the overall 2nd order. Hydrogen ion concentration effect revealed the activeness of both the protonated and deprotonated form of the reductant, positive Brønsted-Debye salt effect and was also ion catalyzed. There was no evidence suggesting an intermediate complex of significant stability in the reaction. Free radical was detected to take part and as such the reasonable mechanistic pathway for the reaction is suggested to be outer-sphere, hence proposed.

Keywords

• Inorganic chemistry
• Kinetics
• Mechanisms
• N,N′-phenylenebis(salicyalideneiminato)cobalt(III)
• l-Cysteine
• Mixed aqueous medium