The spectroscopic and structural properties of copper(II) complexes of the novel tridentate (ONO) pyridine N-oxide ligand Hpoxap

A tridentate ligand (Hpoxap = 2-(o-hydroxyphenyliminomethyl)pyridine N-oxide) has been synthesised by the Schiff condensation of 2-pyridinecarboxaldehyde N-oxide with 2-aminophenol. A series of copper(H) complexes with this ONO-donor ligand has been prepared and their spectroscopic properties (electron, vibration, ESR) Were Studied. The Structures for two complexes have been determined by X-ray analysis. The structure of [Cu(poxap)(OAc)] consists of isolated neutral molecules in which the copper(H) atom is Situated in a slightly distorted square-planar surrounding. The structure of [Cu(poxap)(H2O)(NO3)] consists of neutral molecules which are interconnected by hydrogen bonds giving rise to a ladder structure of copper(II) ions with two different Cu...Cu distances of 5.27 and 7.41 Angstrom. The copper atoms are in a slightly distorted square-pyramidal environment with the tridentate ligand poxap(-) and the water molecule in the basal plane; the apical position being occupied by an oxygen atom of the nitrate anion. Magnetic Susceptibility Studies were undertaken and these confirm predominantly a dimeric character of the complex. (C) 2002 Elsevier science Ltd. All rights reserved.