Protactinium(V) fluoride is a

fluoride Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts typ ...

of protactinium with the chemical formula PaF₅.

Preparation

Protactinium(V) fluoride can be obtained by reacting

protactinium(V) oxide Protactinium(V) oxide is a chemical compound with the formula Pa2 O5. When it is reduced with hydrogen, it forms PaO2. Aristid V. Grosse was first to prepare 2 mg of Pa2O5 in 1927. Pa2O5 does not dissolve in concentrated HNO3, but dissolve ...

with bromine trifluoride or bromine pentafluoride at 600 °C: :3 Pa2O5 + 10 BrF3 (6 BrF5) -> 6 PaF5 + 5 Br2 (3 Br2 ) + 7.5 O2 It can also be obtained by reacting

protactinium(V) chloride Protactinium(V) chloride is the chemical compound composed of protactinium and chlorine with the formula PaCl5. It forms yellow monoclinic crystals and has a unique structure composed of chains of 7 coordinate, pentagonal bipyramidal, protactiniu ...

protactinium(IV) fluoride Protactinium (formerly protoactinium) is a chemical element with the symbol Pa and atomic number 91. It is a dense, silvery-gray actinide metal which readily reacts with oxygen, water vapor and inorganic acids. It forms various chemical compounds ...

with

fluorine Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reacti ...

gas at 700 °C: :2 PaF4 + F2 -> 2 PaF5 The hydrate form of protactinium(V) fluoride can be formed by the reaction of

and

hydrofluoric acid Hydrofluoric acid is a Solution (chemistry), solution of hydrogen fluoride (HF) in water. Solutions of HF are colourless, acidic and highly Corrosive substance, corrosive. It is used to make most fluorine-containing compounds; examples include th ...

in an aqueous solution: :Pa2 O5 + 10 HF -> 2 PaF5 . 2 H2O + 6 H2O It can also be decomposed from fluorine-containing protactinium complexes.

Properties

Protactinium(V) fluoride is a white, volatile, extremely

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance ...

solid that is partially soluble in

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

and soluble in

. It has a tetragonal

crystal structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystal, crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric pat ...

of the β-

uranium pentafluoride Uranium pentafluoride is the inorganic compound with the chemical formula UF5. It is a pale yellow paramagnetic solid. The compound has attracted interest because it is related to uranium hexafluoride, which is widely used to produce uranium fue ...

type with the space group ''I''42''d'' (space group no. 122) with the lattice parameters ''a'' = 1153 pm, ''c'' = 510 pm.

Quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

and Pyrex are attacked by the compound at higher temperatures. As a dihydrate, it is a colourless, hygroscopic, crystalline solid that is waxy in nature. It is soluble in water and hydrofluoric acid. It reacts with

phosphorus trifluoride Phosphorus trifluoride (formula P F3), is a colorless and odorless gas. It is highly toxic and reacts slowly with water. Its main use is as a ligand in metal complexes. As a ligand, it parallels carbon monoxide in metal carbonyls, and indeed ...

to form protactinium(IV) fluoride. The dihydrate cannot be converted into the anhydrous form in air,

hydrogen fluoride Hydrogen fluoride (fluorane) is an inorganic compound with the chemical formula . This colorless gas or liquid is the principal industrial source of fluorine, often as an aqueous solution called hydrofluoric acid. It is an important feedstock i ...

at low temperatures. Instead, diprotactinium(V) oxide octafluoride (Pa₂OF₈) is formed. At higher temperatures around 325 °C, a mixture of the diprotactinium(V) oxide octafluoride and protactinium(V) fluoride is formed.

References

{{Actinide halides Protactinium(V) compounds Fluorides Actinide halides