Studies On Synthesis, Characterization And Catalytic Properties Of Transition Metal Complexes With Schiff Base

Three ligands and their transition metal complexes were synthesized and characterized by elemental analysis, molar conductance, IR, UV-Vis, ¹HNMR, XPS, TG-DTA analysis in the paper. The possible structure of the complexes was proposed. From the results it can be found that the ligand was attached to the metal ion by oxygen and nitrogen atoms and all these complexes were four or six coordinated and 1:1 or 1:2 (metal: schiff base) stoichiometry, these three ligands and their twelve complexes were anhydrous. The catalysis of these three ligands and their complexes in decomposition of hydrogen peroxide were also studied.(1) The Chiral Schiff base I derived from o-Toluidine and D-Camohor-P-Sulfonate and its copper (II), cobalt (II), nickel (II) and zinc (II) complexes were synthesized and characterized by elemental analysis, infrared spectra. The results indicated that the composition of new coordination and its compounds were C₁₇H₂₂NSO₃Na (NaL) and M(C₁₇H₂₂NSO₃)₂(M=Cu²⁺, Co²⁺, Ni²⁺, Zn²⁺)(ML₂), respectively;it was found that NaL acted as N O ligand and all these complexes were six coordinated with 1:2 (metal:schiff base) stoichiometry. The possible coordination pattern of the complexes was also proposed.(2) The Schiff base II derived from salicylaldehycle and o-toluidine and its copper (II), cobalt (II), nickel (II) and zinc (II) complexes were synthesized and characterized by elemental analysis, IR spectra, UV-visible spectra, ¹HNMR, ¹³CNMR and TG-DTA analysis. The possible structure of the complexes was proposed. It can be concluded that the composition of new coordination and its compounds were C₁₄H₁₃NO(L) and M(C₁₄H₁₃NOCl)₂(M=Cu²⁺, Co²⁺, Ni²⁺, Zn²⁺) (ML₂Cl₂), respectively;the ligand was attached to the metal ion by oxygen and nitrogen atoms and all these complexes were six coordinated and 1:2 (metal: schif base) stoichiometry.(3) The unsymmetrical tetradentate Schiff base ligand III and its copper(II), cobalt (II), nickel(II) and zinc(II) complexes were synthesized from the reaction of ethylenediamine, acetylacetone and salicylaldehyde and characterized by elemental analysis, IR, UV-Vis and XPS. The results indicated that the ligand was attached to the metal ion by oxygen and nitrogen atoms. A four-coordinated enol model and 1:2(metal :schif base) stoichiometry were proposed for these complexes, the composition of new coordination and its compounds were CnHig^C^CtbL) and MCi4Hi6N2C>2(M=Cu, Co, Ni, Zn), respectively.(4) The catalysis of these three ligands and their complexes in decomposition of hydrogen peroxide were also studied. Catalytic activity of different complexes in the same condition was tested using the complexes as catalyst and H2O2 as substrate. It can be concluded from the result that catalytic activity of the transition metal complexes were better than that of the transition metal salts;catalytic activity of the transition metal complexes of III were better than that of transition metal complexes of I and II. The difference in the reactivity of the hydrogen peroxide can be explained by unsymmetrical structure of the ligand III;It was found that the catalytic activity of Cu(II) complex was higher than that of other three complexes for the same ligand, such a difference in catalyst efficiency may be related to the property of Cu(II) iron. It was also found that the twelve complexes could be used as effective catalysts for decomposition of hydrogen peroxide.