Close contact distance between hexacyanometallate ions in the course of electron transfer

On the basis of rate constants of redox reactions and stability constants of anion pairs, the contact distances between hexacyanometallate ions in the course of electron transfer were estimated as 6.7–7.1 Å, these values are comparable with the contact anion–anion distances in solids and subtantially lower than the sum of radii of nonhydrated ions.