Synthesis and Structural Studies of Nickel Complex Supported by-ONNO-Tetra Dentate Schiff-Base Ligand: Efficient Catalysts for Oxidation of Phenol

Abstract

Abstract:The free and polymer anchored complex of nickel [3-MHBdMBn-Ni and P-3-MHBdMBn-Ni], supported by -ONNO-tetradentate Schiff-base ligand are prepared by the reactions of nickel solution with one molar equivalent of unsupported 3-MHBdMBn (N, N'-bis (2-hydroxy-3-methylbenzaldehyde) 4-Methylbenzene-1,2-diamine) or polymer supported (P-3-MHBdMBn) Schiff-base ligands in methanol. The structural study reveal that nickel (II) complex of 3-MHBdMBn Schiff base is square planar in geometry. Complexation of nickel ion increased the thermal stability of 3-MHBdMBn Schiff base. The catalytic activity of nickel complex towards the oxidation of phenol is investigated in the presence of hydrogen peroxide. Experimental results indicate that the reactivity of P-3-MHBdMBn-Ni is dramatically affected by the polymer support over 3-MHBdMBn-Ni and the rate of oxidation (R p ) for unsupported one is 1.28 x 10 -6 mole dm -3 s -1 and for supported analogue is 1.99 x 10 -6 mole dm -3 s -1 .