A new oxidovanadium(IV) complex containing an O, N-bidentate Schiff base ligand: Synthesis, characterization, crystal structure determination, thermal study and catalytic activity for an oxidative bromination reaction

A new oxidovanadium(IV) schiff base complex (1) containing an ethyl bromide pendant group was synthesized by the reaction of the related bidentate O, N-Schiff base ligand and VO(acac)2 in a 2:1 ratio in methanol, under reflux conditions. The Schiff base ligand and its vanadyl Schiff base complex were characterized by 1H NMR and FT-IR spectra, and CHN analysis. The crystal structure of 1 was also determined by single crystal X-ray analysis. The vanadium center in this structure has a distorted tetragonal pyramidal N2O3 coordination sphere. The Schiff base ligand HL acts as a bidentate ligand by coordinating via the nitrogen atom of the imine group and the oxygen atom of the phenolic group, thereby forming a six-membered chelating ring. There are some non-classical inter- and intra-molecular hydrogen bonds of the type C–H⋯O and C–H⋯Br in 1. The catalytic activity of 1 was studied for the oxidative bromination of 2-nitrophenol as a model substrate. Different reaction parameters were studied in this reaction and the oxidative bromination of some organic compounds by a catalytic amount of 1 showed that it was an effective and selective catalyst under optimal conditions. Thermogravimeric analysis of 1 showed that it decomposed in two stages. In addition, complex 1 thermally decomposed in air at 660 °C and the XRD pattern of the obtained solid showed the formation of V2O5 nanoparticles with an average size of 57 nm.

A new oxidovanadium(IV) Schiff base complex, VIVOL2, was prepared and characterized by FT-IR spectroscopy, C,H,N and single crystal X-ray analyses. The vanadium(IV) center in this structure has a distorted tetragonal pyramidal N2O3 coordination sphere. The complex was used in the oxidative bromination of organic compounds. The reaction conditions were optimized and the results showed that the complex was a highly active and selective catalyst in this reaction. TGA and thermal decomposition of VOL2 were studied and the latter resulted in the formation of V2O5 nanoparticles.Figure optionsDownload as PowerPoint slide