Protactinium tetrafluoride

Protactinium tetrafluoride is a binary inorganic compound of protactinium metal and fluorine with the chemical formula PaF4.

Synthesis
Protactinium tetrafluoride can be obtained by fluorinating protactinium(IV) oxide with a hydrogen fluoride / hydrogen mixture at 600 °C:


 * PaO2 + 4HF -> PaF4 + 2H2O

The effect of hydrogen fluoride and hydrogen on protactinium(V) oxide:


 * Pa2O5 + 8HF + H2 -> 2PaF4 + 5H2O

Physical properties
PaF4 forms dark brown, monoclinic, needlelike crystals of UF4 structure. The cell parameters are: a = 1.27 nm, b = 1.07 nm, c = 0.842 nm, β = 126.3°.

The compound is soluble in aqueous ammonium fluoride solutions.

Chemical properties
Protactinium tetrafluoride reacts with oxygen and fluorine:


 * 2PaF4 + F2 -> 2PaF5


 * 4PaF4 + O2 -> 2Pa2OF8

The compound reacts with alkalis:


 * PaF4 + 4NaOH -> PaO2 + 4NaF + 2H2O

The compound is displaced from the salt by barium:


 * PaF4 + 2Ba -> Pa + 2BaF2