Abstract

The copper(II) and nickel(II) complexes of the potentially pentadentate ligand (acpn) derived from the Schiff base condensation of 4-azaoctane-1,8-diamine and 5-chloro-2-hydroxybenzophenone have been synthesized and their crystal structures and magnetic and spectral properties determined. The ligands act as pentadentates, in contrast with the coordination reported for some analogous Schiff base ligands. The metal environments are intermediate between square pyramidal and trigonal bipyramidal, with that of [Cu(acpn)] being closer to square pyramidal. The apical bond in the square-pyramidal representation of [Cu(acpn)] is elongated (2.291 Å), though to a markedly smaller degree than in the related complex [Cu(smpn)] (2.374 Å) and the thioether analogue [Cu(scps)] (2.686Å). The crystal structures were determined from full-matrix least-squares refinement of counter data: [Cu(acpn)], space group C2/c,Z 4, a 11.065(4), b 18.481(6), c 14.019(3) Å, β 93.53(3)º, R 3.4% for 2198 reflections; [Ni(acpn)], space group C2/c, Z 4, a 11.084(2), b 18.224(6), c 14.197(6) Å, β 92.57 (3)º, R 3.0% for 1820 reflections.