V2O5/SiO2 surface inspired, silsesquioxane-derived oxovanadium complexes and their properties

Area of Science:

• Inorganic Chemistry
• Materials Science
• Catalysis

Background:

• Surface species on heterogeneous catalysts inspire novel molecular designs.
• Understanding vanadium-silica interactions is crucial for catalyst development.

Purpose of the Study:

• Synthesize novel oxovanadium(v) silsesquioxanes as models for surface species.
• Investigate the coordination chemistry of siloxides with vanadium.
• Evaluate the catalytic activity of these complexes in oxidation reactions.

Main Methods:

• Synthesis of dinuclear and anionic oxovanadium(v) silsesquioxanes.
• Characterization using vibrational spectroscopy, isotopic enrichment, DFT calculations, and X-ray diffraction.
• Catalytic testing for photooxidation of cyclohexane and benzene.

Main Results:

• Formation of a dinuclear compound (2) revealed unfavorable bidentate coordination of geminal siloxides to vanadium.
• An anionic complex (3) with a divalent dioxovanadium unit was synthesized and characterized.
• Complex 3 exhibited significantly higher catalytic activity for benzene to phenol conversion compared to a known catalyst.

Conclusions:

• The study provides molecular insights into vanadium-silica interactions relevant to heterogeneous catalysis.
• Novel oxovanadium(v) silsesquioxanes serve as valuable structural and spectroscopic models.
• Complex 3 shows promise as an efficient catalyst for benzene oxidation.