Non-oxo vanadium(IV) complexes with acetylacetone 4-R-benzoylhydrazones

Abstract

Vanadium(IV) complexes of formula [V(acRbh)2] with acetylacetone 4-R-benzoylhydrazones (H2acRbh, R=H, Cl, OMe and NO2) have been synthesized and characterized by elemental analysis, IR, UV-vis, and electron paramagnetic resonance (EPR) spectroscopic measurements. All the complexes are one-electron paramagnetic and show very similar axial EPR spectra in frozen solution. In dimethylformamide, the complexes display a V(IV)-V(III) redox couple in the E1/2 range -0.16-0.25V (versus Ag/AgCl). Single crystal X-ray structures of [V(acHbh)2] and [V(acClbh)2] have been determined. The metal center in each complex is in a distorted trigonal prismatic N2O4 coordination sphere assembled by the enolate-O, the imine-N, and the iminolate-O donor acRbh2-. © 2012 Taylor & Francis.