Acid-Dissociation Behavior of para-Hydroxyl Group in the N,N,O-Terdentate Ligand, 4-(4-Methyl-2-pyridylazo)resorcinol, Coordinated to a Transition Metal Ion

The acid-dissociation behavior of 1:1 and 1:2 complexes of transition metals with an N,N,O-terdentate ligand, 4-(4-methyl-2-pyridylazo)resorcinol (4-Me PAR), is spectrophotometrically studied in ethanol at 25 °C. The values of apparent pKa of the p-hydroxyl group of the ligand in the metal complexes are found to be in the order, Pd(II)