Synthesis, X-Ray Crystal Structures and Catalytic Epoxidation of Oxidovanadium(V) Complexes Derived from N’-(5-Chloro-2-Hydroxybenzylidene)-3-Methylbenzohydrazide

An aroylhydrazone compound N’-(5-chloro-2-hydroxybenzylidene)-3-methylbenzohydrazide (H₂L) has been synthesized and characterized by elemental analysis, infrared and electronic spectra, and ¹H NMR spectrum. With the aroylhydrazone and maltol (HL^a) or ethyl maltol (HL^b) as ligands, two oxidovanadium(V) complexes, [VOLL^a] (1) and [VOLL^b] (2), have been synthesized and characterized by elemental analysis, infrared and electronic spectra, and ¹H NMR spectra. 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 L, OO donor atoms of maltolate (L^a) or ethyl maltolate (L^b) 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.