Praseodymium(IV) fluoride

Praseodymium(IV) fluoride (also praseodymium tetrafluoride) is a binary inorganic compound, a highly oxidised metal salt of praseodymium and fluoride with the chemical formula PrF4.

Synthesis
Praseodymium(IV) fluoride can be prepared by the effect of krypton difluoride on praseodymium(IV) oxide:
 * $$\mathsf{ PrO_2 + 2 KrF_2 \ \xrightarrow{}\ PrF_4 + O_2 + 2 Kr }$$

Praseodymium(IV) fluoride can also be made by the dissolution of sodium hexafluoropraseodymate(IV) in liquid hydrogen fluoride:
 * $$\mathsf{ Na_2[PrF_6] + 2 HF \ \xrightarrow{}\ PrF_4\downarrow + 2 NaHF_2 }$$

Properties
Praseodymium(IV) fluoride forms light yellow crystals. The crystal structure is anticubic and isomorphic to that of uranium tetrafluoride UF4. It decomposes when heated:
 * $$\mathsf{ 2 PrF_4 \ \xrightarrow{90^oC}\ 2 PrF_3 + F_2 }$$

Due to the high normal potential of the tetravalent praseodymium cations (Pr3+ / Pr4+: +3.2 V), praseodymium(IV) fluoride decomposes in water, releasing oxygen, O2.