A new unsymmetrical tridentate NNS Schiff base ligand, 2-(2-nitrophenylthio)-N-((pyridine-2-yl) methylene)benzenamine (L), and its Mn(II), Ni(II), Cu(II), and Zn(II) complexes were synthesized. These compounds were characterized by different physicochemical and spectroscopic techniques. The molecular structure of [NiL 2 ](ClO 4 ) 2 was determined by single-crystal X-ray diffraction. In this complex, two ligands coordinate through azomethine-N, pyridine-N, and thioether-S, forming a mononuclear 6-coordinate distorted octahedral geometry about a nickel.