Synthesis, crystal structures and catalytic activity of oxidovanadium(V) complexes with tridentate ONO aroylhydrazone ligands

Abstract

Two oxidovanadium(V) complexes, [VOL1(OEt)] (1) and [V2O2(L2)2(OEt)2] (2), where L1 and L2 are the anions of 2-amino-N′-(2-hydroxybenzylidene)benzohydrazide (H2L1) and N′-(2-hydroxybenzylidene)-4-hydroxybenzohydrazide (H2L2), respectively, 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 atom in the mononuclear complex 1 is in square pyramidal coordination, and those in the dinuclear complex 2 are in octahedral coordination. Both aroylhydrazone ligands coordinate to the V atoms through the phenolate O, imino N, and enolate O atoms. The ethanol ligand in complex 1 is in terminal coordination mode, while that in complex 2 is in bridging coordination mode. The complexes function as effective olefin epoxidation catalysts with hydrogen peroxide as terminal oxidant and sodium hydrogen carbonate as a co-catalyst.