Manganese (II)-imidazole complexes of the non-steroidal anti-inflammatory drug mefenamic acid: Synthesis, and structural studies

Two new complexes of Mn(II) have been synthesized with a non-steroidal anti-inflammatory drug, mefenamic acid, 2-[(2,3-dimethylphenyl)amino]benzoic acid (mef) and the nitrogen donor ligands; imidazole (imi) and 2-methylimidazole (mei), viz. [Mn(mef)(2)(imi)(2)(EtOH)(2)]; M-1 and [Mn(mef)(2)(mei)(2)(EtOH)(2)]; M-2. Also, when mefenamic acid interacted with MnCl2 center dot 4H(2)O in the presence of 2-aminopyridine (apy), a salt of ((mef)(apy) (H2O)); M-3 was isolated. The complexes were characterized using elemental analysis, FTIR, UV-Visible (M-1 and M-2), and single-crystal X-ray diffraction studies. Monodentate coordination of the mefenamate ligand in M-1 and M-2 was confirmed from the FTIR studies. The X-ray structural analysis shows that the two Mn(II) complexes and one salt crystallize in the triclinic space group P-1. M-1 consists of monomeric Mn(II) in hexacoordination with two monodentate mefenamate, two imidazoles, and two ethanol solvent ligands. M-2 consists of monomeric Mn(II) complex in octahedral geometry and coordinated to two each of monodentate mefenamate, 2-methylimidazole, and two ethanol solvent ligands. M-3 consists of salt of mefenamate anion linked to an aminopyridinium cation, with a hydrogen-bonded water molecule present in the crystal lattice which connects the cation and anion via intermolecular O-H center dot center dot center dot O and N-H center dot center dot center dot O interactions.