Redox reactions

This chapter analyses redox reactions. It explains that the oxidation–reduction reactions of transition metal complexes proceed via two primary mechanistic pathways: outer and inner sphere reactions. An outer sphere mechanism occurs when an electron is transferred between two coordination complexes in solution, both of the coordination spheres remain intact, and no ligand is transferred between them. The chapter notes that it is only possible to establish such a mechanism unambiguously when both of the coordination complexes are substitutionally inert. Finally, the chapter describes the inner sphere mechanism: the electron transfer is mediated by an ambidentate ligand which is capable of bridging the two metal centres in the transition state and is transferred from one complex to the second in the course of the reaction.