A dioxidomolybdenum(VI) complex chelated with salicylaldehyde-3-methoxybenzhydrazone: Synthesis, crystal structure and catalytic activity.

• Aroylhydrazone-based dioxidomolybdenum(VI) complex was synthesized. • Structure elucidation of aroylhydrazone and Mo(VI) complex by single crystal X-ray diffraction. • Mo center adopts a distorted octahedral geometry. • Mo(VI) complex functions as a catalyst in the cyclooctene epoxidation. • Mo(VI) complex displayed a 97 % yield of cyclooctene epoxide. A dioxidomolybdenum(VI) complex, [MoO 2 (SMBH)(DMSO)] derived from tridentate ONO aroylhydrazone, salicylaldehyde-3-methoxybenzhydrazone (SMBH 2), has been synthesized. The investigation of the structural characteristics of both aroylhydrazone and its molybdenum(VI) complex were conducted using various spectroscopic techniques (FT-IR, UV–Vis, 1H NMR, MS) and analytical methods (elemental and single crystal XRD analysis). The molecular structures of the aroylhydrazone and molybdenum(VI) complex were confirmed through single-crystal X-ray diffraction (XRD) studies. The presence of the amido form of the aroylhydrazone in the solid state was corroborated through IR spectroscopy and single-crystal XRD. The aroylhydrazone, salicylaldehyde-3-methoxybenzhydrazone (SMBH 2), and its Mo(VI) complex got crystallized in monoclinic space group P 2 1 /c and triclinic space group P 1 ‾ respectively. The molybdenum complex exhibits a distorted octahedral geometry, with the aroylhydrazone serving as a bi-anionic tridentate donor ligand. The molybdenum(VI) centre in the complex is coordinated by the aroylhydrazone, two oxido groups, and an oxygen atom from the DMSO solvent. Non-covalent interactions, such as hydrogen bonding, C–H···π interactions, and π···π interactions, contribute to the stabilization of the crystal structures of both the aroylhydrazone and the molybdenum complex. The developed molybdenum complex showed potential as a catalyst for the cyclooctene epoxidation reaction, achieving a conversion of 97 % to produce 1,2-epoxycyclooctane under ambient reaction conditions. [Display omitted] [ABSTRACT FROM AUTHOR]