ThF4

ThF4, or thorium(IV) fluoride, is an inorganic compound consisting of thorium in the +4 oxidation state coordinated to fluoride. It is typically a white crystalline solid at room temperature and is one of the principal fluoride salts of thorium. The compound is relatively stable in dry air but hydrolyzes slowly upon exposure to moisture, forming thorium oxyfluoride species.

Preparation and properties: ThF4 is usually prepared by fluorinating thorium oxides or hydroxides with fluorinating agents such as hydrofluoric acid or fluorine gas, or by low-temperature fluorination of thorium salts with fluoride sources. In the solid state it is insoluble in water and tends to form polymeric networks built from Th–F bonds. In solution, fluoride ligands can coordinate to Th4+, generating various soluble fluoride complexes under appropriate conditions. The compound has a high melting point and is used as a chemical precursor in thorium chemistry, including conversion to other thorium fluorides, oxides, and in fluoride-volatility methods.

Applications and safety: ThF4 is used as an intermediate in procedures to prepare thorium compounds and in some fluoride-volatility processes relevant to thorium fuel-cycle chemistry. Because thorium is radioactive, handling ThF4 requires appropriate radiological controls; fluoride compounds are corrosive and can be hazardous if inhaled or ingested. Materials should be stored dry and protected from moisture.