The kinetics of aquation of nitropentamminecobalt perchlorate

Abstract

The kinetics of aquation of [Co(NH₃)₅NO₂]²⁺ have been studied in the range 60–97° by following, spectrophotometrically, the rate of disappearance of the complex ion at various concentrations of perchloric acid. Pseudo-first-order spontaneous and acid-catalysed aquations occur simultaneously. Arrhenius parameters have been determined for both reactions. The pre-exponential term of the Arrhenius equation of the acid-catalysed reaction is of the same order of magnitude as that of the reaction with hydroxyl ions. The high values can be explaned by mechanisms involving pre-equilibria.