Complexation Behavior of Benzene-1,2-Diyldimethaniminedibenzoic Acid towards Divalent Metal Ions

New Schiff base ligand (benzene-1,2-diyldimethaniminedibenzoic acid) was prepared via condensation of o-phthaldehyde and 2-aminobenzoic acid in 1:2 ratio. Metal complexes were prepared and characterized using elemental analyses, IR, molar conductance, electronic spectra, ¹H NMR and ¹³CNMR. From the elemental analyses and spectra data, the complexes were proposed to have the general formulae [M(L₂)] (where M=Co(II), Ni(II), Cu(II) and Zn(II)). The molar conductance data revealed that all the metal chelates were non-electrolytes. IR spectra suggested coordination to the metal ions in a bi-negative tetradentate manner with NOON donor sites of the azomethine-N and carboxylate-O. The ¹H NMR spectral data indicate that the two carboxylate protons are also displaced during complexation. Formula determination using method of continuous variation gave metal:ligand ratio of 1:1. Based on spectra studies, a tetrahedral geometry have been proposed for the complexes.