Reactivity of the hydrated electron with (ω-carboxylatoalkyl)ferricenium zwitterions. A radiation chemical study

Abstract

Rate constants have been determined for the reaction of the hydrated electron with the substituted ferricenum zwitterions obtained by one-electron oxidation of 3-ferrocenylpropanoate, 4-ferrocenylbutanoate and 5-ferrocenylpentanoate anions. These values are all close to 3 × 10¹⁰ dm³ mol^–1 s^–1 and since, on the basis of the equation of von Smoluchowski, this implies that reaction occurs when the centres of the reactants are at a separation of at least 7 Å, it would appear that these reactions are diffusion-controlled. Thus the sandwiching of the iron atom between two cyclopentadienyl groups does not appreciably alter the high reactivity towards the hydrated electron of the ferric part, whose complexes with inorganic ligands are known to react at the diffusion-controlled limit.