Mechanically-induced solvent-less synthesis of cobalt and nickel complexes of cimetidine

Solvent-less synthesis of [Co[(CIM).sub.2]](S[O.sub.4]) and [Ni[(CIM).sub.2]][(OAC).sub.2] by grinding of CoS[O.sub.4] and Ni[(C[H.sub.3]COO).sub.2].4[H.sub.2]O with cimetidine without any solvent is described. The complexes have been characterized by elemental analysis, melting point, AAS, conductivity measurements, TLC, infrared and UV-Vis spectroscopies as well as X-ray powder diffraction. Cimetidine was found to be bidentate or tridentate ligand. Cobalt ion coordinate with cimetidine through the sulphur atom in the thiol group, nitrogen atom of imidazole ring and the nitrogen atom of the secondary amine to give an octahedral geometry with ligand acting as tridentate whereas nickel ion coordinates through the sulphur atom in the thiol group, nitrogen atom of imidazole ring to give tetrahedral structure with ligand acting as bidentate. X-Ray diffraction patterns of the complex were different from that of the ligand suggesting formation of coordination compounds. The method is quick and gives a quantatively yield, without the need for solvents or external heating. Clearly, it can present higher efficiency in terms of materials, energy and time compared to classical solution phase synthesis. Keywords: solvent-less synthesis; cimetidine; X-Ray diffraction pattern; mechanochemistry; green chemistry