Influence of the nature of an organic solvent on the kinetic parameters of the thermal homolysis of five-coordinate complexes of alkylcobalt

By the spectrophotometric method in solvents of different natures a study was made of the kinetics of the homolytic breakage of the axial cobalt-carbon bond in five-coordinate complexes with dianionic tetradentate equatorial ligands. The negative values obtained for the activation entropies of the processes investigated are explained by the existence of interaction between the components of the primary radical pair and the solvent molecules. The kinetic parameters of the redox-interaction reactions of some macrocyclic complexes of cobalt(II) with chloroform and carbon tetrachloride were determined. A scheme in which the autocatalytic homolysis of the Co-CH ₃ bond in the presence of chlorine-containing solvents is proposed.L. V. Pisarzhevskii Institute of Physical Chemistry, Ukrainian Academy of Sciences, Kiev 252028. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 838–844, April, 1992.