Vanadiumoxo–aroylhydrazone complexes: Synthesis, structure and DFT calculations

The aroylhydrazone Schiff base ligands (E)-N’-(2-hydroxybenzylidene)benzohydrazide = H2L1, (E)-N’-(2-hydroxy-3-methoxybenzylidene)benzohydrazide = H2L2 and = (E)-N’-(5-bromo-2-hydroxybenzylidene)benzohydrazide = H2L3 gave the vanadium(V)oxo-aroylhydrazone complexes [VVOL1(OCH3)(OHCH3] (1), [VVOL2(OCH3)(OHCH3]·CH3OH (2) and [VVOL3(OCH3)(OHCH3] (3) on reaction with vanadium(IV) oxide acetylacetonate. The complexes were characterized by spectroscopic methods in the solid state (IR) and in solution (UV–Vis, 1H NMR). Single crystal X-ray analysis was performed with 3. In methanol solution six-coordinated VVOL3(OCH3)(OHCH3) was formed. VIV was oxidized to Vv by aerial oxygen in the synthesis. In the VO5N coordination sphere the alcohol oxygen lies trans to the oxo oxygen. The general V–O bond length order is oxo < methoxylato < phenoxidic < enolato < alcoholic. The complexes are mononuclear, but intermolecular O–H⋯N hydrogen bonding affords a zigzag chain. DFT calculations on complex 3 reproduced the geometric parameters, IR and UV–Vis spectroscopic data well in a reasonable range.

The aroylhydrazone Schiff base ligands and their vanadium(V)oxo complexes [VVOL1(OCH3)(OHCH3] (1), [VVOL2(OCH3)(OHCH3]·CH3OH (2) and [VVOL3(OCH3)(OHCH3] (3) were synthesized (H2L1–3 = (2-hydroxybenzylidene)benzohydrazide derivatives). Single crystal X-ray analysis was performed with 3. DFT calculations on complex 3 reproduced geometric parameters, IR and UV–Vis spectroscopic data well in a reasonable range.Figure optionsDownload as PowerPoint slide