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

Abstract

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.