Synthesis and characterization of a series of acylpyrazolone transition metal complexes: Crystal structures and catalytic performance in the epoxidation of cyclooctene

A series of transition metal complexes of 4-acetyl-3-methyl-1-phenyl-2-pyrazoline-5-one with Ni(II), Cu(II), Fe (III) and Mn (II) central metal ions have been synthesized and characterized by X-ray crystallography, UV-Vis and FTIR spectroscopy, and elemental analysis. The complexes were used as a catalyst for epoxidation of cyclooctene with tert-butylhydroperoxide. Various parameters, including catalyst type and amount, solvent type and amount, oxidant/substrate ratio and time, have been optimized. The highest catalytic activity was found for Cu(II) complex at the optimized conditions. Very high selectivity for the epoxide product (cyclooctene oxide) was also obtained.