VO(IV), Fe(III), Co(II) AND Cd(II) COMPLEXES OF ASYMMETRIC SCHIFF BASE LIGANDS (N_2O_3). SYNTHESIS AND SPECTROSCOPIC STUDIES

摘要

New series of mononuclear VO(IV), Co(II) and Cd(II) complexes of the formula (HLVO(OH_2)).nH_2O, (HLCo).xH_2O and (HLCd).xH_2O and binuclear Fe(III) complexes of the formula (LFe_2Cl_2(H_2O)_3)Cl.H_2O have been synthesized. L stands for one of the five asymmetrical pentadentate (N_2O_3) Schiff base ligands H_3L~1-H_3L~5 prepared by the condensation of acetoacetylphenol and ethylenediamine in the molar ratio 1:1 to prepare a half-unit Schiff base which is further condensed with one of the following aldehydes and ketones: o-hydroxyacetohpenone, salicylaldehyde, naphthaldehyde, benzoylacetone or acetylacetone. These ligands possess two dissimilar coordination sites, an inner, four-coordinating N_2O_2 donor set and an outer, three-coordinating O_2O set. The complexes were characterized by IR, electronic, ESR and mass spectra as well as conductivity and magnetic measurements. The magnetic moments of the VO(IV) complexes at room temperature are higher than expected for a single electron due to orbital contributions, while antiferromagnetic interaction is observed in the binuclear Fe(III) complexes due to interaction between two adjacent Fe(III) ions. The mass spectra of the complexes show base peaks with m/e values corresponding to the molecular weights of the complexes. The coordination numbers for the vanadium and iron ions are six with octahedral geometries and the coordination numbers for the cobalt and cadmium ions are four with tetrahedral geometries.