H4SnF6

H4SnF6, also known as hexafluorostannic acid, is an inorganic compound with the chemical formula H4SnF6. It is a strong acid formed from the reaction of tin(IV) fluoride with hydrofluoric acid. In aqueous solution, hexafluorostannic acid exists as a complex mixture of species, including hydrated SnF6^2- anions and protonated forms of fluoride.

Hexafluorostannic acid is a colorless, crystalline solid that is highly soluble in water and polar solvents. It is corrosive and should be handled with appropriate safety precautions. Its primary applications are in electroplating, where it is used as an electrolyte for depositing tin and tin alloys. It is also employed in the manufacturing of certain types of glass and ceramics, and as a catalyst in organic synthesis.

The compound can be prepared by dissolving tin(IV) oxide or tin metal in hydrofluoric acid, followed by treatment with excess fluoride ions. Purification typically involves crystallization from aqueous solutions. Due to its acidic and corrosive nature, its storage and handling require specialized equipment and procedures.