Synthesis, Complexation and Characterization of 1-Phenyl-3-Methyl-4- (p-nitrobenzoyl) Pyrazolone-5(HNPz) and its complexes of Barium(II), Strontium(II) and Zinc(II)

Complexes of Ba(II), Sr(II) and Zn(II) with 1-phenyl-3-methyl-4- (p-nitrobenzoyl) pyrazolone-5(HNPz) have been synthesized and characterized. The HNPz was prepared from high grade p-nitrobenzoyl chloride and 1-phenyl-3-methyl-5-pyrazolone. The process involved benzoylation of 17.60 g (0.10 M) 1-phenyl-3-methyl-5-pyrazolone (HPMP) with 14.55 g (0.103 M) nitrobenzoylchloride. The complexes of Ba (II), Sr (II) and Zn (II) were prepared by dissolving 5 mmol of BaCl2.2H2O,SrCl2.6H2O and ZnSO4.7H2O respectively in 10 mmol of HNPz. The complexing agent and the metal complexes were characterized by elemental analysis, UV-visible and infrared spectroscopies. The results show the complexes to be dihydrated bischelates conforming to a general molecular formula, MLn.2H2O, where L is the 4-acylpyrazolonato ion and n is the ligand number or oxidation state of metal,M (Ba, Sr, Zn). The study also indicates the formation of octahedral complexes which are presumed to have been formed through the enolic and carbonyl oxygen atoms of the coordination reagent; in which water molecules complete the expected coordination numbers of Ba(II), Sr(II) and Zn(II).