Transition metals as switches

In this article it is demonstrated that transition metals are among the best candidates for the role of molecular switches, on account of the following peculiar properties: (i) They can form couples of consecutive oxidation states, A and B, easily interconverted through a fast and reversible one-electron redox change. The relative stability of the two states (which is expressed exactly by the standard electrode potential associated with the half-reaction) can be modulated by properly varying the coordinative environment around the metal center. (ii) The one-electron change in most cases modifies drastically the properties of the metal center (stereochemical preferences, magnetism, electron-transfer tendencies, binding affinity toward a donor atom)