Mechanism of the Reaction between the Aqua Complexes of Palladium(II) and Iron(II) in a Solution of HClO4

The kinetics of the reaction of an aqua complex of iron(II) with a tetraaqua complex of palladium(II) in a perchloric acid solution was studied over the temperature range 20–55°C, and a reaction mechanism was proposed. It was found that the reaction is autocatalytic, and it occurs by a two-step one-electron transfer mechanism with the formation of iron(III) and palladium black. Based on the kinetic data, the nature of the autocatalysis in the test reaction was hypothesized.