Synthesis of 1‐(1‐H‐Benzotriazolyl‐1‐acetyl)‐5‐hydroxy‐3‐trifluoromethyl‐5‐(2‐thienyl)‐2‐pyrazoline and Its Transition Metal Complexes

Abstract 1‐(1H‐Benzotriazol‐1‐acetyl)‐5‐hydroxy‐3‐trifluoromethyl‐5‐(2‐thienyl)‐2‐pyrazoline (H2L) has been synthesized by condensing 1H‐benzotriazol‐1‐acetic acid hydrazide with 1‐(2‐thienyl)‐4,4,4‐trifluoro‐1,3‐butanedione. Complexes of the composition [ML]2 [M = Zn(II), Cu(II), Ni(II)] and [ML(H2O)]2 [M = Co(II)] have been prepared by refluxing the pyrazoline and metal acetate hydrates in ethanol. The ligand and its complexes have been characterized by elemental analyses, IR, 1H NMR, magnetic susceptibility measurements, and thermogravimetric analysis (TGA). The spectra show that the ligand H2L coordinates as tridentate ligand through the enolic oxygens and the nitrogen of the azomethine group. For the complex [ML(H2O)]2, the S atom of the thienyl group also coordinates with the metal.