Peroxo-Thorium(IV)-Containing Heteropolytungstates and Their Oxo-Analogues: Synthesis, Structure and Solution Studies

Area of Science:

• Inorganic Chemistry
• Materials Science
• Coordination Chemistry

Background:

• Polyoxotungstates are versatile inorganic clusters with diverse applications.
• Thorium-based materials are of interest for their unique properties.
• The synthesis of novel polyoxometalates expands the scope of coordination chemistry.

Purpose of the Study:

• To synthesize and characterize new peroxo-thorium(IV)-containing silico- and germanotungstates.
• To investigate the structural features of these novel compounds.
• To explore the reactivity and properties of thorium in polyoxotungstate frameworks.

Main Methods:

• Aqueous synthesis involving thorium(IV) cations and trilacunary polytungstate precursors.
• Addition of hydrogen peroxide to form peroxo-complexes.
• Crystallization as hydrated mixed rubidium-sodium salts.
• Single-crystal X-ray diffraction for structural elucidation.
• Solution studies using 183W NMR and electrochemical methods.

Main Results:

• Successful synthesis of four polyanions: peroxo-thorium(IV) silico- and germanotungstates (Th3O2Si, Th3O2Ge) and their oxo-analogues (Th3Si, Th3Ge).
• Structural determination revealed a central triangular thorium core sandwiched by {A-α-XW9O34} fragments.
• The peroxo-thorium(IV) structures exhibit a rare side-on μ3-coordination of the peroxo group to three thorium centers.
• These represent the first peroxo-thorium(IV)-containing polyoxotungstates.

Conclusions:

• A straightforward two-step aqueous procedure enables the synthesis of novel peroxo-thorium(IV) polyoxotungstates.
• The unique side-on μ3-coordination of the peroxo group highlights new structural motifs in inorganic chemistry.
• These findings open avenues for exploring thorium-based polyoxometalates with tailored properties.