Synthesis and Characterization of a New Unsymmetrical Potentially Pentadentate Schiff Base Ligand and Related Complexes with Manganese(II), Nickel(II), Copper(II), Zinc(II) and Cadmium(II)

New unsymmetric thioether Schiff base amine, 2-(2-aminoethylthio)-N-(thiophene-2-ylmethylene)aniline was prepared by reaction of 2-aminothiophenol with N-(2-bromoethyl)phthalimide and then by thiophene-2-carbaldehyde. Then, the phthalimide group converted to the amine by hydrazine hydrate. The new potentially pentadentate N₃S₂ donor unsymmetrical Schiff base ligand, 2-(2-(pyridine-2-ylmethyleneamino)ethylthio)-N-(thiophene-2-ylmethylene)aniline (L) was prepared via [1 + 1] condensation of pyridine-2-carbaldehyde with this amine. Manganese(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes of this ligand were prepared by adding metal salts to an ethanolic solution in this ligand. The thioether amine, ligand (L) and unsymmetric Schiff base complexes are characterized by the appropriate spectroscopic methods such as infrared (IR), UV-Vis, ¹H nuclear magnetic resonance (NMR), ¹³C NMR studies, X-ray, microanalysis and mass spectrometry.

Keywords:
N₃S₂ donor; pentadentate ligand; unsymmetrical ligand; Schiff base complexes; thioether ligand