Synthesis, Crystal Structures and Catalytic Oxidation Property of Two Copper(II) Complexes Derived from 5-Bromo-2-((2-piperazin-1-ylethylimino)methyl)phenol

Abstract

Two new copper(II) complexes, [Cu(HL)(ONO₂)]NO₃ (1) and [CuCl(HL)]Cl∙H₂O (2), where HL is the zwitterionic form of the Schiff base 5-bromo-2-((2-piperazin-1-ylethylimino)methyl)phenol (HL), have been prepared. The Schiff base and two complexes were characterized by IR and UV-Vis spectroscopy. In addition, the free Schiff base was characterized by ¹H NMR spectroscopy. Structures of the complexes were further confirmed by single crystal X-ray diffraction. The Cu atoms in the complexes are in square planar coordination. Crystal structures of both copper complexes are stabilized by hydrogen bonds. The complexes have high catalytic activity for the epoxidation of styrene, with conversions and selectivity over 90%.