Kinetic studies of complex formation between Co(II) ion and 2,2 -bipyridine with UV-Vis and Stopped flow techniques

Macrocycle molecules are an interesting class of compounds that have attracted much attention in recent years. Specifically, the coordination chemistry community has been interested in the study of such compounds due to the increased kinetic inertness and thermodynamic stability of their metal complexes compared to their acyclic analogues [1,2]. In this project kinetics and mechanism of the reaction between cobalt(II) choloride and 2,2 -bipyridine as a bidentate ligand were investigated using UV-Vis spectrophotometry technique. The results indicated that reaction follows a second order reaction. Overall rate constants (kobs), activation energy (Ea) and other parameters (Δ?‡،Δ?‡,Δ?‡ )were reported. In addition, useful information were obtained on the rate of reaction from study of effects of temperature and solvent. Experimental data exhibited that second step of each reaction is a rate determining step (RDS). In addition, fast step of reaction was studied by Stopped – Flow method. Also determination of reaction stoichiometries was recognized by the Yoe and Jones method. The results indicated that the cobalt (II) and 2,2 -bipyridine stoichiometric ratio is 1: 3.