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

The reaction of magnesium ca rbonate with orlilo or para-aminobenzoic acid results in the formation of the complexes I Mg(1-I 10)61(Xh,2 1-1 20 (X=2-aminobenzoate (2-aba) 1 and X=4-aminobenzoate (4-aba) 2). The 2-aminobenzoatc complex I has been characteri sed by metal analysis. isothermal weight loss studi es, infrared, UV-V is, 11-1 and I3C NMR spectra and xray powder diffraction. The 2-aba complex is relatively unstable as compared to the corresponding 4-aba anal ogue and slowly decomposes to I Mg(2-abahl with the loss of water molecules. This irreversible change is allributedto the disposit ion of the H ~ group with respect to the carboxy late group in the six-membered ring.