Synthesis, characterization and antitumour activity of iron(II) and iron(IlI) complexes of 3- and 5-substituted salicylaldehyde benzoyl hydrazones

Abstract

Iron(II) and iron(III) complexes of tridentate ligands derived from various substituted salicylaldehydes and benzoyl hydrazones have been prepared and characterized by elemental analysis, conductance measurements, magnetic susceptibilities (from room temperature down to liquid N 2 temperature), and Mössbauer, electronic and infrared spectral studies. On the basis of these studies the following structures are suggested: monomeric, high-spin, five-coordinate for Fe(XSBH)SO 4·H 2O (XSBH = substituted salicylaldehyde benzoyl hydrazone, X = H, 3-CH 3O, 3-NO 2, 5-Cl, 5-Br, 5-CH 3 or 5-NO 2); dimeric, high-spin, phenoxide bridged, five-coordinate for Fe(H-SBH)Cl (H-SBH = salicylaldehyde benzoyl hydrazone); and monomeric, high-spin, six-coordinate for Fe(XSBH) Cl 2·H 2O (X = 3-CH 3O, 3-NO 2, 5-Cl, 5-Br, 5-CH 3 or 5-NO 2). Intermolecular antiferromagnetic exchange interaction is present in the dimeric Fe(XSBH)Cl complex, where the exchange parameter is −7.3 cm −1. The complex exhibits an asymmetrical quadrupole-split doublet in its 57Fe Mössbauer spectra. The asymmetry is found to be temperature dependent with a relatively symmetrical doublet at low temperature. All these complexes have been screened for their antitumour activity against the P388 lymphocytic leukaemia test system in mice and have been found to possess no significant activity at the dosages employed.