Synthesis, characterization and antitumor activity of some metal complexes of 3- and 5-substituted salicylaldehyde o-hydroxybenzoylhydrazones

Abstract

Complexes of Mn(II), Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and Pt(II) with 3- and 5-substituted salicylaldehyde o-hydroxybenzoylhydrazones (XSBH, X = H, 3-NO 2, 3-CH 3O, 5-Cl, 5-Br, 5-CH 3 or 5-NO 2) have been prepared and characterized by elemental analysis, conductance measurements, magnetic susceptibilities (from room temperature down to liquid nitrogen temperature) and spectral studies. These studies indicate the following structures: monomeric, high-spin, distorted octahedral for Mn(XSBH) 2; monomeric, high-spin, five-coordinate for Fe(XSBH)SO 4·H 2O; dimeric, high-spin phenoxide bridged, five-coordinate for Fe(XSBH)Cl; dimeric, high-spin five-coordinate for Co(XSBH)Cl·2H 2O; dimeric low-spin, five-coordinate for Ni(XSBH)Cl·2H 2O; dimeric, four-coordinate for Zn(XSBH); and a square-planar structure for M(XSBH)Cl·H 2O (M = Cu(II) or Pt(II). Intermolecular antiferromagnetic exchange interactions are present in Fe(III) complexes, where the exchange parameter ( J) is ca. −8.0 cm −1 for these complexes. The Fe(III) complexes exhibit asymmetric quadrupole split doublets in their 57Fe Mössbauer spectra. The asymmetry is found to be temperature dependent with relatively symmetrical doublets seen at low temperature. The polycrystalline ESR spectra of Cu(II) complexes are isotropic and indicate a d x 2−y 2 ground state in square-planar stereo-chemistry. All these metal complexes have been screened for their antitumor activity against the P 388 lymphocytic leukaemia test system in mice and enhanced antitumor activity relative to the free ligand was found but no significant activity at the dosages used.