UNUSUAL COMPLEXING PROPERTIES OF 2-(2'-PYRIDYL)- AND 2-HYDRAZINO-8-HYDROXYQUINOLINE

The ligands 2-(2′-pyridyl)- and 2-hydrazino-8-hydroxyquinoline form terdentate complexes with a 5,5-bicyclic ring system, the stabilities being greater than those of the corresponding 8-hydroxyquinolinates. This study affords a more complete picture of the behaviour of terdentate 2-substituted 8-hydroxyquinolines. Solutions of these ligands and metal ions are complicated by formation of the protonated species MHL2+, M(HL)2+2 and MLHL+. The existence of the protonated species is dependent not only on pH and ligand:metal-ion molar ratio but also on the nature of the metal ion itself. © 1979.