Modeling the Oxygen Vacancy at a Molecular Vanadium(III) Silica-Supported Catalyst

Area of Science:

• Inorganic Chemistry
• Materials Science
• Catalysis

Background:

• Isolated vanadium atoms on silica are crucial intermediates in oxidation catalysis.
• Understanding their electronic structure and coordination is key to optimizing catalytic activity.
• Polyoxotungstates offer a versatile platform for modeling such systems.

Purpose of the Study:

• To synthesize and characterize a molecular model for single-site vanadium on silica.
• To investigate the electronic structure and coordination environment of vanadium species.
• To elucidate the role of apical ligands and electronic configuration in vanadium-oxo species.

Main Methods:

• Synthesis of a silanol-decorated polyoxotungstate support.
• Coordination of vanadium(III) to the polyoxotungstate.
• Characterization using SQUID magnetometry, DFT calculations, EPR, Raman spectroscopy, and spectroelectrochemical studies.

Main Results:

• A vanadium(III) complex supported by a polyoxotungstate was successfully synthesized.
• The complex models reduced isolated vanadium atoms on silica surfaces.
• Electronic structure analysis revealed the influence of apical ligands and geometrical distortions on vanadium d-orbitals, including a unique bireduced species with decoupled d1-V(IV) and d1-W(V) centers.

Conclusions:

• The silanol-decorated polyoxotungstate serves as an effective molecular support for single-site vanadium.
• The study clarifies the electronic behavior of vanadium species relevant to oxidation catalysis.
• Apical ligand coordination and geometrical factors significantly impact vanadium orbital stabilization and electronic delocalization.