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

New Schiff base complexes of Mn-II, Cu-II and Zn-II of the type [M(HL)CH3COO(H2O)]center dot 2H(2)O (M = Mn), [M(HL)CH3COO(H2O)] (M = Cu or Zn), H2L = N-(4-carboxyphenyl)salicylaidimine, 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 : 1. 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 Mn-II and Zn-II complexes are essentially tetrahedral. Thermal study indicate that Cu-II and Zn-II complexes are thermally stable up to a temperature of ca. 150 degrees C, whereas manganese(II) complex undergo loss of two molecules of lattice water between 120-125 degrees C, followed by the loss of coordinated water molecule between 190200 degrees C. Mn-II complex has demonstrated its catalytic potential in oxidizing the selective organic substrate viz. benzyl alcohol by H2O2 as the oxidant.