Electron transfer reaction accompanied by a structural change. In the case of reaction with [Ru(NH3)(5)(butyl sulfoxide)](2+) and cis-[Ru(NH3)(4)(pyridine-4-carboxamide)(2)](3+)

The oxidation of [Ru(NH3)(5)(butyl sulfoxide)](2+) by cis-[Ru(NH3)(4)(pyridine-4-carboxamide)(2)](3+) has been studied as a case of an electron transfer reaction accompanied by a structural change. Even in an excess of one of the reaction partners, the reaction shows complex kinetic behavior. Treatment of the experimental data points to a mechanism in which the first step is an up-hill electron transfer between the complexes and in which the second step involves isomerization of the unstable sulfoxide complex produced in the first step.