New molybdenum (VI) catalyst for the epoxidation of alkenes and oxidation of sulfides: An experimental and theoretical study

• A new molybdenum(VI) dioxido complex was synthesized.
• Structure of the complex was established by single-crystal X-ray crystallography.
• The AIM analysis was employed for visualizing the bond paths.
• The experimental studies have been accompanied computationally by the DFT studies.
• The obtained complex proved to be an efficient catalyst for oxidation reactions.

The preparation and catalytic activity of molybdenum(VI) dioxido complex [MoO2L(C2H5OH)] (L = N′-[1-(2-hydroxynaphthyl)ethylidene]-2-hydroxy benzohydrazide) are reported. The reaction of the respective benzohydrazide ligand and the Mo(VI) dioxido precursor, [MoO2(acac)] (acac = acetylacetonate), in ethanol afforded the [MoO2L(C2H5OH)] complex. Structure of the complex was unequivocally established by single-crystal X-ray crystallography. The X-ray structure of complex reveals a six coordinate molybdenum center with a distorted octahedral geometry. By using the AIM analysis, topological properties of the electron density were analyzed to define the bond path between atoms. The AIM calculations indicate that the ligand H2L coordinates to the molybdenum ion in the enol-enamine form (not keto-amine). An insight in the electronic structure of the complex was also obtained by using the density functional theory (DFT). The [MoO2L(C2H5OH)] complex was successfully applied as a catalyst in both, the epoxidation of olefins with tert-butyl hydroperoxide (TBHP) and the oxidation of sulfides with urea hydrogen peroxide (UHP), to form the corresponding sulfoxides.

The preparation, crystal structure and catalytic activity of a new molybdenum(VI) dioxido complex are reported. By using the AIM analysis, topological properties of the electron density were analyzed. To get an insight into the electronic structures of the studied complex, the (U)B3LYP/DFT optimized calculations were carried out.Figure optionsDownload as PowerPoint slide