Synthesis, structural characterization and spectroscopy studies of new oxovanadium(IV, V) complexes with hydrazone ligands

The reaction of vanadyl acetoacetonate, VO(acac)2, with 2-hydroxybenzaldehyde hydrazone in ethanol gave the mononuclear oxovanadium(IV) complex [VO(salh1)2] (1). However, when the hydrazides 3-hydroxy-2-naphthoic acid hydrazide (h2) and 5-phenylisoxazole-3-carboxylicacidhydrazide (h3) were used, the mononuclear oxoethoxovanadium(V) complexes [VO(acanh2)(OEt)] (2) and [VO(acanh3)(OEt)] (3) were isolated, respectively. The reaction with benzene-1,4-dicarbohydrazide (h4) in a water–ethanol solution gave polynuclear {[VO(μ-EtO)2](μ-acanh4)}n (4). The complexes were characterized by elemental analysis, IR, UV–Vis and 51V NMR spectra. Magnetic susceptibility measurements indicated the +5 vanadium oxidation state in 2, 3 and 4 and +4 in 1. X-ray single crystal diffraction studies revealed that the vanadium(V) center has a distorted square pyramidal geometry in 2 and 3, and a distorted octahedral geometry in 4, with an O3N coordination environment around the V(V) acceptor center. Complex 4 is a polymeric compound with dihydrazide ligand as a linker and each two vanadium ions are connected via two μ-ethoxo bridges.

Four vanadium complexes with hydrazone ligands were characterized by IR, UV–Vis, NMR, cyclic voltammetry and magnetic susceptibility measurements. X-ray crystal structures of two monomeric and one polymeric compound are described.Figure optionsDownload as PowerPoint slide