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Pyrrole Ligands. III . The Stability of Dipyrromethenato Complexes of Cu (II) and Ni (II) in Aqueous Solutions
Author(s) -
Stünzi Hans,
Anderegg Giorgio
Publication year - 1979
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19790620130
Subject(s) - chemistry , protonation , aqueous solution , pyrrole , titration , ligand (biochemistry) , nitrogen atom , nitrogen , medicinal chemistry , inorganic chemistry , crystallography , group (periodic table) , ion , organic chemistry , biochemistry , receptor
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 (KNO 3 )). The p K values for the NH groups are 8.03 and 16.1 and logβ 2 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.