Kinetic study of the base hydrolysis reaction of fluoropenta-amminechromium(III) cation

Abstract

The second-order rate constants for the base hydrolysis of Cr(NH₃)₅F²⁺ have been measured by use of a polarographic technique. The Arrhenius parameters for the reaction are compared with previously obtained data for the base hydrolysis of the corresponding chloro-, bromo-, and iodo-complexes. The results are in general agreement with an associative-type mechanism (l_a), similar to that previously proposed for the base hydrolysis of the other three halogeno-complexes.

The effect of added anions such as pyrophosphate, in decreasing the rate of base hydrolysis is discussed in terms of outer-sphere complex formation between the fluoro-complex and the added anions. This observed decrease in the rate of base hydrolysis is also in accordance with an associative-type process.