Synthesis, Characterization and Kinetic Studies of Nickel (Ii) Complex of Dibenzoyl Methane and It’s Adduct

Abstract

Nickel (II) Complex of dibenzoylmethane and the 1, 10 phenantroline adduct were synthesized using Nickel (II) acetate tetrahydrate in aqueous methanol. The resulting green Ni²⁺ compounds were characterized by elemental analysis, magnetic moments, IR and UV spectroscopy. The kinetics of the reaction for the formation of the complex   was conducted. The complex and adduct were identified by coupled vibrations of Ni-O + Ni-N which were conspicuously absent in the neat ligand .The elemental and metal analysis indicates 1:2 Metal-Ligand ratio in both complex and adduct. The electronic spectral and magnetic susceptibility studies are consistent with the adoption of an octahedral geometry for the adduct.  Results of the kinetic study showed that the formation of the nickel complex occurs at a rate of 1.7 x 10³ – 9.2 x 10³ moldm^-3 in a 2^nd order  reversible reaction, which involved both the metal and the ligand with equilibrium constant K_eq ranging from 2.0 x 10⁴ – 1.5 x 10⁶. The observed rate is at variance with the rate of solvent exchange, this being typical of a tautomeric ligand.

Keywords: 1, 10-phenantroline, Dibenzoylmethane, Kinetics, Solvent-exchange.