Synthesis, structure and catalytic activity of new oxovanadium(V) complexes with deferiprone and N,N-donor ligands

Abstract

A pair of new water-soluble oxovanadium(V) complexes comprising of deferiprone (def) and N,N-donor ligands, 2,2ʹ-bipyridine (bpy) or 1,10-phenanthroline (phen), [VO2(def)(bpy)]⋅H2O (1) and [VO2(def)(phen)]⋅4H2O (2) were synthesized. The complexes were characterized by elemental analysis, spectral studies and single crystal X-ray diffraction analysis. The X-ray crystal structures of 1 and 2 reveal that both the complexes possess distorted octahedral coordination geometries with O4N2 coordination sphere around the vanadium center, and the deprotonated deferiprone occupying the equatorial plane. The complexes 1 and 2 efficiently catalyzed selective epoxidation of styrene with 30% H2O2 under ecologically sustainable organic solvent-free conditions, at ambient temperature. The catalysts afforded good styrene conversion and high TON value along with excellent epoxide selectivity (>99%). Recyclability of the catalysts at least up to three consecutive cycles without significant alteration in activity or selectivity, is an additional remarkable feature of the developed catalytic protocol.