The Inner-sphere Activated Complex for the Electron Exchange of Iron(II) and the Monochloro Complex of Iron(III)

Abstract

The kinetics of the iron(II)-catalyzed dissociation of FeCl24 have been studied by the use of a flow technique. The rate constant for the dissociation is given by £<i = k¡ + k-i/{H+) + ^(Fe2*), where k, = 1.1 ± 0.2 sec.-1, k'2 = 3.4 ± 0.6 M sec. -1, and kt = 12.1 ± 1.6 M~x sec. -1 at 25.0°and ionic strength 3.0 M. The kinetics of the iron(II)-iron(III) electron exchange in the presence of chloride ions were studied using a radioactive tracer method. The rate constant for the electron exchange between FeCl2and Fe24" was found to be 57.6 ± 2 M~l sec.-1 at 25.0°and ionic strength 3.0 M. The results suggest that the electron exchange between FeCl2* and Fe2* proceeds mainly by a chloride-bridged inner-sphere activated complex.(1) Research performed under the auspices of the U. S. Atomic Energy Commission.(2) J.

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