Structural investigation of the catalytic activity of Fe(III) and Mn(III) Schiff base complexes

Abstract Two novel manganese (III) and iron (III) complexes of an N,N-bis(1-naphthalidimine)-o phenylene diamine ligand have been successfully synthesized and characterized by various analytical techniques including single crystal X-ray structure analysis. The ligand crystallizes in the monoclinic system with space group P21/c. The detailed analyses of Hirschfeld surface and fingerprint plots provide insight into the nature of non-covalent interactions in the ligand. Experimental data have been complemented and interpreted in the light of Density Functional Theory calculation was performed using the B3LYP method concerning molecular geometries, vibrational frequencies and electrochemical potentials. Cyclic voltammetry in dimethylformamide revealed reversible redox processes in both complexes, suggesting possible catalytic reactivity involving electron transfer process for these complexes. The catalytic efficiency and selectivity of manganese (III) and iron (III) complexes was tested in the oxidation of cyclohexene with molecular oxygen. The results show that the catalytic performance depends on the nature of metal, the most efficient catalyst in the presence of O2beingthe iron (III) complex. A plausible mechanism for cyclohexene oxidation by complexes is proposed and discussed hereafter.