Synthesis and characterization of a series of copper(II) complexes with azo-linked salicylaldimine Schiff base ligands. Crystal structure of Cu5PHAZOSALTN·CHCl3

Article abstract of DOI:10.1016/S0277-5387(99)00380-0

Complexes of copper (II) with Schiff bases obtained by condensation of 5-phenylazo salicylaldehyde with di-or tri-amines have been synthesized and characterized by their infrared spectra and elemental analysis. The copper(II) chelates investigated are [bis(5-phenylazo salicylaldehyde)ethylene diiminato]copper(II) (Cu5PHAZOSALEN) (I), [bis(5-phenylazo salicylaldehyde)O-phenylene diiminato]-copper(II) (Cu5PHAZOSALOPHEN) (II), [bis(5-phenylazo salicylaldehyde)trimethylen diiminato]copper(II) (Cu5PHAZOSALTN) (III) and [bis(5-phenylazo salicylaldehyde)diethylene triiminato]copper(II) (Cu5PHAZOSALDETA) (IV). The single-crystal X-ray diffraction is reported for Cu5PHAZOSALTN·CHCl₃. The copper atom lies in a near square-planar coordination with Cu-N bond lengths of 1.962(7) and 1.949(7) A? and Cu-O lengths of 1.903(5) and 1.931(6) A?. Cyclic voltammetry indicates that copper complexes III and IV have a quasi-reversible redox behaviour and complexes I and II undergo irreversible and reversible reduction (at a scan rate 0.05 V s^-1), respectively, under the experimental conditions. (C) 2000 Elsevier Science Ltd.