Synthesis, characterization and thermal studies of magnesium (II) complexes of ortho and para-aminobenzoic acids

Abstract

The reaction of magnesium carbonate with ortho or para-aminobenzoic acid results in the formation of the complexes [Mg(H2O)(6)](X)(2).2H(2)O (X=2-aminobenzoate (2-aba) 1 and X=4-aminobenzoate (4-aba) 2). The 2-aminobenzoate complex 1 has been characterised by metal analysis, isothermal weight loss studies, infrared, UV-Vis, H-1 and C-13 NMR spectra and X-ray powder diffraction. The 2-aba complex is relatively unstable as compared to the corresponding 4-aba analogue and slowly decomposes to [Mg(2-aba)(2)] with the loss of water molecules. This irreversible change is attributed to the disposition of the -NH2 group with respect to the carboxylate group in the six-membered ring.