Novel oxovanadium and dioxomolybdenum complexes of tridentate ONO-donor Schiff base ligand: Synthesis, characterization, crystal structures, Hirshfeld surface analysis, DFT computational studies and catalytic activity for the selective oxidation of benzylic alcohols

Selective oxidation of benzylic alcohols with proposed mechanism. [Display omitted] •Synthesis of novel ONO tridentate Schiff base ligand and its oxovanadium and dioxomolybdenum complexes.•Characterization by FT-IR, 1H NMR, 13C NMR and CHN analysis.•Single crystal X-ray diffraction (SC-XRD) analysis of VOL and MoO2L complexes.•Hirshfeld surface analysis (HSA)•DFT calculation by B3LYP/Def2-TZVP method.•Comparison of experimental results with theoretical investigations. Two new oxovanadium and dioxomolybdenum Schiff base complexes, [VvO(L)(OCH3)(CH3OH)] and [MoVIO2(L)(CH2CH3OH)], were synthesized by treating an ONO-donor type Schiff base ligand (H2L) derived by condensation of 5-nitrosalicylaldehyde 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, multinuclear (1H, 13C) NMR, elemental analysis and the most authentic single crystal X-ray diffraction analysis. In both complexes the geometry around the central metal ions was distorted octahedral as revealed by the data collected from diffraction studies. Theoretical calculation of the synthesized compounds were carried out by DFT as well as TD-DFT using B3LYP method by employing the Def2-TZVP basis set. The findings of theoretical data indicated that the calculated results are in accordance with the experimental findings. Moreover, the catalytic efficiencies of both complexes were investigated by oxidizing the benzylic alcohols in the presence of urea hydrogen peroxide (UHP) in acetonitrile.