CYCLIC VOLTAMMETRY AND SPECTROELECTROCHEMISTRY OF RHODIUM PHTHALOCYANINES

The electrochemistry of Rh(III)(pc) (pc = phthalocyanine dianion) comp lexes containing chloride, pyridine, dimethyl sulfoxide (dmso) and cya nide as axial ligands was investigated by cyclic voltammetry and UV/VI S spectroelectrochemistry. The compounds were K[Rh(pc)(CN)2], [Rh(pc)( Cl)(py)] and [Rh(pc)CI(dmso)]. For all of these the first oxidation oc curs at the phthalocyanine ligand with the formation of a pi-cation ra dical species. The addition of one electron to the complexes leads to one of two different reduction products depending on the nature of the axial ligands. The first reduction of [Rh(pc)Cl(py)] and [Rh(pc)Cl(dm so)] occurs at the metal, followed by rapid dimerization of the reduce d species. The first and subsequent reductions of K[Rh(pc)(CN)2] occur at the ring.