Zinc(II) trinuclear complexes involving pyridine N-oxide ligands: distortion isomerism and magnetic properties of copper(II) analogues

The Schiff condensation of the 2-pyridinecarboxaldehyde N-oxide with 2-amin ophenol yielded a tridentate ligand, abbreviated as Hpoxap. This ligand is a base of a series of mononuclear complexes (M(poxap)(2)] and trinudear com plexes of the type [M(poxap)MX4M(poxap)], where X is an acetate or chloro b ridge. The X-ray structure of the complex [Zn(poxap)Zn(OAc)(4)Zn(poxap)]. H 2O has been determined. this complex forms a pair of distortion isomers dif fering slightly in bond lengths and bond angles within the chromophores. Th e copper(II) doping gave mixed crystals suitable for the ESR spectroscopy ( g(\\) = 2.282, g(perpendicular to) = 2.016, A(\\) = 135 G, A = 26 G)(.) The magnetic susceptibility of an analogous [Cu(poxap)CuCl4Cu(poxap)] trinucle ar complex at low temperature indicates a slight antiferromagnetic interact ion (J(Cu-Cu)/hc = - 5.2 cm(-1), g(Cu) = 2.285). (C) 2000 Elsevier Science S.A. All rights reserved.