Synthesis, spectral characterization and reactivity study of new Schiff base complexes of divalent manganese, copper and zinc

Department of Chemistry, Tripura University, Suryamaninagar-799 130, West Tripura, India E-mail : rndp@rediffmail.com Manuscript received 14 May 2008. revised 8 September 2008. accepted 17 September 2008 New Schiff base complexes of MnII , CuII and ZnII of the type [M(HL)CH3COO(H2O)]2H2O (M = Mn), [M(HL)CH3COO(H2O)] (M = Cu or Zn), H2L = N-(4-carboxyphenyl)salicylaldimine, have been synthesized from the reaction of the Schiff base ligand with the respective metal acetate in a methanolic solution maintaining the metal to ligand ratio as 1 : J. Complexes have been characterized on the basis of elemental analyses, FT-IR, NMR, ESR, electronic spectroscopy, room temperature magnetic moment measurements and by TGA/DTA studies. The results of above studies suggest that the newly synthesized complexes are tetra coordinated and Schiff base is acting as bidentate ligand, ligated to the metal center through its phenolic oxygen and azomethine nitrogen atoms respectively. Copper(II) complex appears to be square planar:- while MnII and ZnII complexes are essentially tetrahedral. Thermal study indicate that CuII and ZnII complexes are thermally stable up to a temperature of ca. 150°C, whereas manganese(ll) complex undergo loss of two molecules of lattice water between 120-125°C, followed by the loss of coordinated water molecule between 190- 200°C. MnII complex has demonstrated its catalytic potential in oxidizing the selective organic substrate viz. benzyl alcohol by H2O2 as the oxidant