Synthesis, X-Ray Crystal Structures and Catalytic Epoxidation of Oxidovanadium(V) Complexes with Aroylhydrazone and Ethyl Maltolate Ligands

Abstract

Two oxidovanadium(V) complexes, [VOL¹L] (1) and [VOL²L] (2) (L = ethyl maltolate), derived from the aroylhydrazones 4-bromo-N’-(2-hydroxy-5-methylbenzylidene)benzohydrazide (H₂L¹) and N’-(3,5-dibromo-2-hydroxybenzylidene)-4-methoxybenzohydrazide (H₂L²), respectively, have been synthesized and characterized by elemental analysis, infrared and electronic spectroscopy. Structures of the complexes were further confirmed by single crystal X-ray determination. The V atoms in the complexes are coordinated by the ONO donor atoms of the aroylhydrazone ligand, OO donor atoms of the ethyl maltolate ligand, and one oxido O atom, forming octahedral coordination. The complexes function as effective olefin epoxidation catalysts with hydrogen peroxide as terminal oxidant and sodium hydrogen carbonate as a co-catalyst.