Synthesis, characterization, crystal structures, Hirshfeld surface analysis, DFT computational studies and catalytic activity of novel oxovanadium and dioxomolybdenum complexes with ONO tridentate Schiff base ligand

Abstract For the first time, two new oxovanadium and dioxomolybdenum Schiff base complexes, VOL(OMe) and MoO2L, were synthesized through the reaction of a ONO tridentate Schiff base ligand (H2L) derived from the condensation of 5-bromosalicylaldehyde and nicotinic hydrazide with oxo and dioxo acetylacetonate salts of vanadium and molybdenum, [VO(acac)2 and MoO2(acac)2], respectively. The synthesized ligand and complexes were characterized by various spectroscopic techniques like FT-IR, 1H NMR, 13C NMR, elemental analysis (CHN) and the most authentic single crystal X-ray diffraction analysis (SC-XRD). The geometry around the central metal ion in MoO2L was distorted octahedral as revealed by the data collected from diffraction studies. Non-covalent interactions that are responsible for crystal packing are explored by Hirshfeld surface analysis. Theoretical calculations of the synthesized compounds, carried out by DFT at B3LYP/Def2-TZVP level of theory, indicated that the calculated results are in agreement with the experimental findings. Moreover, the catalytic activities of both complexes were investigated for the selective oxidation of benzylic alcohols using urea hydrogen peroxide (UHP) in acetonitrile.