Synthesis, Characterization and Molecular Mechanics Potential Energy Evaluation of 4-Amino-2, 3-Dimethyl-1-Phenyl-3-Pyrazolin-5-One Ligand and its Transition Metal Complexes

4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one is a metabolite of aminopyrine with analgesic, antiinflammatory, and antipyretic properties. Cd(II), Co(II), Cu(I), Ni(II), Pt(II) and Zn(II) complexes of 4-amino- 2,3-dimethyl-1-phenyl-3-pyrazolin-5-one have been synthesized. The ligand and complexes were characterized based on electronic, infrared, ¹H NMR and ¹³C NMR spectroscopy. Spectroscopic investigation revealed that the ligand coordinated to the metal ions through the carbonyl and amino functional groups. 4-amino-2,3-dimethyl-1- phenyl-3-pyrazolin-5-one behaved as a bidentate ligand. Five membered ring chelates complexes were formed. Molecular mechanics potential energy evaluation showed that the most feasible position for 4-amino-2,3- dimethyl-1-phenyl-3-pyrazolin-5-one and its complexes to exhibit analgesic, anti-inflammatory and antipyretic activity was found to be in the range 56.75143626 - 82.65547188 kcal/mol.