Vanadium precursors and the type of complexes formed with Schiff base ligand composed of 5-bromosalicylaldehyde and 2-hydroxybenzhydrazide – Structure and characterization

Abstract

Five vanadium(IV) and (V) complexes, with Schiff base ligand, based on three vanadium precursors such as [VO(acac)2], VOSO4 and V2O5 were synthesized and characterized. Only the last vanadium substrate, in a very simple synthesis, with the addition of triethylamine, results in formation of the crystalline product for which crystal structure measurements were performed. Two vanadium(IV) complexes were stabilized by adding a co-ligand (5-chloro-1,10-phenantroline or 2,2′-bipyridine). Three complexes of vanadium(V) were obtained, one dioxido and two oxido, with an EtO- or MeO- molecule as a ligand (depending on the solvent used in the synthesis). A single X-ray crystal study revealed that the anionic dioxido complex poses a distorted tetragonal pyramid geometry of vanadium. For all complexes, the elemental analyses, magnetic measurements, including EPR spectra for V(IV) complexes, and IR and UV–Vis spectra are presented and discussed. The relationship between the vanadium precursor used and the complex obtained has been described in detail.