Some New Unsymmetrical Diimino Tetradentate Schiff Base Derived from 3,4-Diaminobenzophenone: Synthesis, Characterization and the Formation Constant of Ni(II) and Cu(II) Complexes

Some new unsymmetrical diimino tetradentate Schiff bases derived from 3,4-diaminobenzophenone, (N-salicyliden-N'-5-OMe.salycyliden)-3,4-diaminobenzophenone (H2sal-5-OMe.sal.dabp) (H2L1), (H2sal-5-Br.sal.dabp) (H2L2), (H2sal-5-Cl.sal.dabp) (H2L3) and (H2sal-5-NO2.sal.dabp) (H2L4) and their Ni(II) and Cu(II) complexes were synthesized and characterized by elemental analysis, IR, 1H NMR, UV-Vis spectra and mass spectra. The thermodynamic formation constants of the complexes were determined spectrophotometrically at constant ionic strength (0.1 M NaClO4) at 25 �°C in DMF and their free energies of formation were calculated at 25 �°C.