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

Complexes of copper (II) with Schiff bases obtained by condensation of 5-ph enylazo salicylaldehyde with di-or tri-amines have been synthesized and cha racterized by their infrared spectra and elemental analysis. The copper(II) chelates investigated are [bis(5-phenylazo salicylaldehyde) ethylene diimi nato] copper(II) (Cu5PHAZOSALEN) (I), [bis(5-phenylazo salicylaldehyde) O-p henylene diiminato]copper(II) (Cu5PHAZOSALOPHEN) (II), [bis(5-phenylazo sal icylaldehyde) trimethylen diiminato] copper(II) (Cu5PHAZOSALTN) (III) and [ bis(5-phenylazo salicylaldehyde) diethylene triiminato] copper(II) (Cu5PHAZ OSALDETA) (IV). The single-crystal X-ray diffraction is reported for Cu5PHA ZOSALTN CHCl3. The copper atom lies in a near square-planar coordination wi th Cu-N bond lengths of 1.962(7) and 1.949(7) Angstrom and Cu-O lengths of 1.903(5) and 1.931(6) Angstrom. Cyclic voltammetry indicates that copper co mplexes 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 All rights reserved.