Synthesis, characterization and X-ray crystal structures of copper(II) and nickel(II) complexes with potentially hexadentate Schiff base ligands

• Published in: Inorganica Chimica Acta 2005-07, Vol.358 (11), p.3211-3217
• Main Authors: Khandar, Ali Akbar, Hosseini-Yazdi, Seyed Abolfazl, Zarei, Seyed Amir
• Format: Article
• Language: English
• Subjects: 5-Phenylazo salicylaldehyde; Conductivity; Copper(II) complexes; Cyclic voltammetry; Nickel(II) complexes; Schiff base; X-ray structure
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2005.04.028

Copper(II) and nickel(II) complexes of potentially N 2O 4 Schiff base ligands were synthesized and characterized by a variety of physio-chemical techniques. In this work, emphasis has been given to the examination of structural relationships in the complexation behavior. We also assume that increasing the length of alkyl linkage may induces a distortion of the coordination geometry from square-planar to octahedral. Copper(II) and nickel(II) complexes of potentially N 2O 4 Schiff base ligands 2-({[2-(2-{2-[(1-{2-hydroxy-5-[2-phenyl-1-diazenyl]phenyl}methylidene)amino] phenoxy}ethoxy) phenyl]imino}methyl)4-[2-phenyl-1-diazenyl]phenol (H 2L 1) and 2-({[2-(4-{2-[(1-{2-hydroxy-5-[2-phenyl-1-diazenyl]phenyl}methylidene)amino] phenoxy}butoxy) phenyl]imino}methyl)4-[2-phenyl-1-diazenyl]phenol (H 2L 2) prepared of 5-phenylazo salicylaldehyde ( 1) and two various diamines 2-[2-(2-aminophenoxy)ethoxy]aniline ( 2) and 2-[4-(2-aminophenoxy)butoxy]aniline ( 3) were synthesized and characterized by a variety of physico-chemical techniques. The single-crystal X-ray diffractions are reported for CuL 1 and NiL 2. The CuL 1 complex contains copper(II) in a near square-planar environment of N 2O 2 donors. The NiL 2 complex contains nickel(II) in a distorted octahedral geometry coordination of N 2O 4 donors. In all complexes, H 2L 1 behaves as a tetradentate and H 2L 2 acts as a hexadentate ligand. Cyclic voltammetry of copper(II) complexes indicate a quasi-reversible redox wave in the negative potential range.