| Abstract: | The protonation and complex formation of the new ligand 3,3′, 5,5′-tetramethyl-dipyrromethene-4,4′-dicarboxylate in aqueous solutions was investigated by alkalimetric titrations and spectrophotometric measurements (25°, I = 1 (KNO3)). The pK values for the N? H groups are 8.03 and 16.1 and logβ2 of the complexes with Cu (II) and Ni (II) are 31.0 and 24.4, respectively. Comparison with other ligands shows that the dipyrromethenato group acts as a normal rigid aromatic dinitrogen ligand, despite the charge on one nitrogen atom. |
