ELECTROCHEMICAL REDUCTION OF NEW TETRADENTATE LIGANDS

The electrochemical reduction of a set of four tetradentate ligands, each containing one bipyridine and one pyridyl triazine as molecular subunits, was analysed on mercury electrodes in dimethylformamide as solvent. The diazo group of the triazine subunit is the first reduction site of these ligands. Despite their similar chemical composition, two out of the four ligands exhibited original redox characteristics. They contrasted with the two other ligands in this set, of which redox properties reflected directly those of the components. Substituents in alpha and beta position to the diazo groups, together with protic acidity, have significant effects on the first reduction step of the ligands. The proton-driven changes in the first reduction step do not alter the co-ordination capability of the ligands.