Kinetics and Mechanism of Substitution of Chloride Ion in trans-[Co(en)₂Cl₂]⁺ by Organic Bases in Dimethyl Acetamide Solution

M. Asadi* and K. Mohammadi

Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454, Iran 

(Received 8 June 2003, Accepted 29 September 2003)

      The kinetics of substitution of chloride ion in trans-dichlorobis(ethylenediamine) cobalt(III) cation by five organic bases (diethylamine, triethylamine, benzylamine, t-butylamine and n-propylamine) in dimethylacetamide (DMA) at ionic strength of 0.80 M NaClO₄ is reported. The activation parameters for the second-order path lie on a good isokinetic line. The linear plots of k_obs vs. [B], the large negative values of ÄS₂^‡ and the span of k₂ values signify an associative mechanism.

 Keywords: Kinetics, Mechanism, Substitution reaction, Organic bases