REDOX ACTIVATION OF ORGANOMETALLICS - THE ELECTROCHEMICAL INITIATION OF THE ISOMERIZATION-REACTIONS OF ORGANOMETALLIC PI-COMPLEXES

Basic principles governing redox activation of the 18-electron complex es of transition metals are considered. In essence, this process conve rts the above complexes to 17-electron or 19-electron radical-ions via the abstraction or addition of an electron, respectively. The latter radical-ions exhibit significantly enhanced reactivity. The feasibilit y of the electrochemical initiation of the isomerization reactions for complexes with polydentate ligands, which occur concomitant with a ch ange in the metal coordination site, is shown using sandwich and semis andwich pi-complexes of transition metals. Particular emphasis is plac ed on examining reactions of inter-ring haptotropic isomerization for pi-complexes of metals with polycyclic aromatic ligands that are induc ed by electron transfer. The isomerization involves migration of the m etal from one ring to another along the plane of the nn-electron syste m of the ligand.