ELECTROCHEMISTRY OF IRIDIUM-BIS-(PHENANTHROLINE) COMPLEXES

Cyclic voltammetry data have been obtained for the bis(1,10-phenanthroline) (phen) and bis(5,6-dimethyl-1,10-phenanthroline) (5,6-Mephen) complexes of iridium(III) in acetonitrile. A reaction mechanism is proposed on the basis of the analysis of electrochemical and luminescence data. For these bis complexes the electron transfer sequence is interrupted at several steps by the elimination of chloride ion. Comparison of the voltammetry for the two bis Ir(III) complexes suggests that the adsorption interaction observed for the phen complex involves a Zeiss type interaction between the Pt electrode and the C5-C6 bond of a phen ligand. Although the luminescence of the phen and 5,6-Mephen complexes apparently is of different orbital origin (charge transfer and ligand localized), the redox orbitals deduced from the electron transfer sequences are the same for the two complexes. © 1979 American Chemical Society.