Studies on Bis(Para Anisidine Acetylacetonato) Nickel (II) Complex

Abstract

Schiff base was prepared from the reaction of para anisidine and acetylacetone. Bis(para anisidineacetylacetonato)nickel(II) complex was synthesized by the reaction of the prepared para anisidineacetylacetone ligand and nickel(II) chloride. The prepared Schiff base is orange yellow, has a yield of 61.90% and melting point of 86^oC. The complex prepared is red, has a yield of 71% and decomposition temperature of 270^oC. The para anisidineacetylacetone ligand is soluble in water and most organic solvents, similarly, its nickel(II) complex compound is soluble in most solvents except water and methanol, in which it slightly soluble. The molar conductance of bis(para anisidineacetylacetonato)nickel (II) complex compound determined is 4.70 ohm^-1 cm²mol^-1, suggesting that the complex is non-electrolyte. The infra-red spectral data of para anisidine and acetylacetone base showed a medium size band in the range 1595 – 1630cm^-1, attributable to v(C=N) stretching vibrations, the same band is observable in the nickel(II) complex, indicating coordination of the ligand to the nickel(II) ion. The broad band in the range 3257 - 3420 cm^-1 observed in para anisidineacetylacetone ligand is assigned to v(O-H) stretching vibrations, which is absent in anisidineacetylacetonato)nickel(II) complex, as a result of deprotonation of the para anisidineacetylacetone on coordination to the nickel(II) ion. The dissociation constant (pKa) of para-anisidine acetylacetone determined is 12.66. The stability constant of anisidineacetylacetonato)nickel (II) complex compound determined is 1.29x106 and the corresponding Gibb’s free energy of complex is -3.48 x10⁴ KJ per mole. The average number of para anisidine ligand coordinated to nickel(II) ion determined using potentiometer is 2, suggesting a four coordinate complex compound.

Keywords: Anisidineacetylacetone, complex compound, stability constant, potentiometry.