Solvolysis of the [Cr(NCS)4(benztriazole)2]- ion in ethanol-water mixtures

Measuring the concentration of the free thiocyanate ion and the nontransformed [Cr(NCS)(4)(benztriazole)(2)](-) ion, the rate constants of the solvolysis process have been calculated. The solvolysis includes two parallel reactions - the substitution of thiocyanate ions and of benztriazole molecules. The first stage of the solvolysis is the substitution of a single SCN-; this reaction is of first order with regard to the complex ion. This reaction is followed by the very fast substitution of the second SCN-. The parallel benztriazole substitution reaction seems to be a third order one, first order with regard to the complex ion and second order with regard to ethanol. The influence of the acidity has been studied.