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It has been suggested that Hg2+-promoted reaction of a series of cis-[Co(en)2(L)Cl]2+ (en = 1,2-diaminoethane) with L = NH3, NH2CH3, glyOC2H5, glyOCH3, dl-alaOC2H5, NH2CH2CONH2, and NH2CH2CN proceeds by dissociative interchange(Id) mechanism from kinetic data, circular dichroism spectra, analyses of products, and the values of m(Grunwald-Winstein plot) using Y (solvent ionizing power) in aqueous solution and in mixed aqueous-organic solvent. It has been found that chloride replacement by water (aquation) for the series with L = NH3 and NH2CH3 and chelation of ligand L to Co(Ⅲ) for the series with L = glyOC2H5, glyOCH3, dl-alaOC2H5, NH2CH2CONH2, and NH2CH2CN occurs, respectively. The rate constants on Hg2+-induced reaction of the series except cis-[Co(en)2(NH2CH2CN)Cl]2+ were increased with increasing the contents of ethanol in mixed water-ethanol solvents. In mixed water-30% organic solvents, the rate constants of the series except cis-[Co(en)2(NH2CH2CN)Cl]2+ have also been measured in the order 30% 2-propanol-water > 30% ethanol-water > water. However, the rate constants of cis-[Co(en)2(NH2CH2CN)Cl]2+ were reversed. The rate constants of the series with L= NH3 and NH2CH3 were related to ligand field parameter (△), but those of the series with L = glyOC2H5, glyOCH3, dl-alaOC2H5, NH2CH2CONH2, NH2CH2CN were not. The reaction between the series and Hg2+ in aqueous media containing NO3- has been investigated. The results for the reaction do not alter the mechanism, but the rate only was altered.
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