Synthesis of 1-benzotriazolylacetyl-5-hydroxy-3-methyl-5-phenyl-2-pyrazolines and their transition metal complexes

1-(1H-Benzotriazol-1-acetyl)-5-hydroxy-3-methyl-5-phenyl-2-pyrazoline (H2L1) and 1-(2H-benzotriazol-2-acetyl)-5-hydroxy-3-methyl-5-phenyl-2-pyrazoline (H2L2) have been synthesized by condensing 1H-benzotriazol-1-acetic acid hydrazide or 2H-benzotriazol-2-acetic acid hydrazide with 1-phenyl-1,3-butanedione. Complexes of the type [ML](2) and [M(HL)(AcO)] [M = Zn(II), Cu(II), Ni(II)] have been prepared by refluxing the pyrazolines with the metal acetate hydrates in ethanol. The ligands and their complexes have been characterized by elemental analyses, IR, H-1 NMR and MS spectra. The spectra show that the ligands H2L1 and H2L2 coordinate as tridentate ligands through the enolic oxygens and the nitrogen of the azomethine group with opening of the pyrazoline rings.