{Ti₆}/{Ti₁₀} Wheel Cluster Substituted Silicotungstate Aggregates

Area of Science:

• Inorganic Chemistry
• Materials Science
• Catalysis

Background:

• Silicotungstates (STs) are versatile polyoxometalates with diverse structures and applications.
• Titanium-oxo clusters offer unique structural motifs and reactivity.
• Developing novel polyoxometalates with enhanced catalytic properties is an active research area.

Purpose of the Study:

• To synthesize and characterize novel titanium-oxo wheel cluster substituted silicotungstates.
• To investigate the catalytic oxidation properties of the synthesized compounds, particularly for sulfide oxidation.
• To evaluate the recyclability and stability of the active catalyst.

Main Methods:

• Hydrothermal synthesis was employed to prepare the novel silicotungstate compounds.
• Structural characterization was performed to elucidate the composition and architecture of the polyoxoanions.
• Catalytic oxidation reactions using hydrogen peroxide as the oxidant were conducted to assess catalytic activity.
• Recyclability studies were performed to evaluate the stability and reusability of the catalyst.

Main Results:

• Two novel Ti-oxo wheel cluster substituted silicotungstates, [H2N(CH3)2]9H9[Ti6O6(SiW10O37)3]·11H2O (1) and [H2N(CH3)2]16H10[Ti10O11(SiW10O37)2(SiW9O35)2]·14H2O (2), were successfully synthesized.
• Compound 1 features a ring-shaped trimer with a Ti6O6 wheel cluster encapsulated by three SiW10O37 fragments.
• Compound 2 contains an unprecedented Ti10O11 double-wheel cluster, representing a rare structure in polyoxometalate chemistry.
• Compound 1 exhibited high catalytic activity in the oxidation of various sulfides using H2O2.
• Compound 1 demonstrated excellent recyclability, maintaining its catalytic activity over at least five cycles.

Conclusions:

• Novel titanium-oxo wheel cluster substituted silicotungstates have been synthesized, expanding the structural diversity of polyoxometalates.
• The synthesized silicotungstate 1 shows significant potential as an efficient and recyclable catalyst for sulfide oxidation.
• The findings highlight the importance of incorporating Ti-oxo wheel clusters into silicotungstate frameworks for catalytic applications.