Synthesis, characterization and the thermodynamic studies of some unsymmetrical tetradentate Schiff-base ligands and their Ni(II) and Cu(II) complexes

Some new unsymmetrical tetradentate Schiff-base ligands, (N-salicylidene-N'-pyrrolidene)-1,2-ethylenediamine(H(2)salpyren) (H2L1), (H(2)Mesalpyren) (H2L2), (H(2)phsalpyren) (H2L3), (N-salicylidene-N'-pyrrolidene)-1,3-propylenediamine (H(2)salpyrpd) (H2L4), (H(2)Mesalpyrpd) (H2L5), (H(2)phsalpyrpd) (H2L6) and their Ni(II) and Cu(II) complexes were synthesized and characterized by elemental analyses, IR, UV-Vis, 1H NMR and mass spectra and magnetic moments. Possible structures of these complexes have been proposed. The thermodynamic formation constants of the complexes were determined spectrophotometrically at constant ionic strength 0.1 M (NaClO4), at 25 degrees C in methanol.