Plutonium tetrafluoride

Plutonium(IV) fluoride is a chemical compound with the formula PuF₄. This salt is generally a brown solid but can appear a variety of colors depending on the grain size, purity, moisture content, lighting, and presence of contaminants.^[4][5] Its primary use in the United States has been as an intermediary product in the production of plutonium metal for nuclear weapons usage.^[3]

Plutonium tetrafluoride^[1]

A sample of plutonium tetrafluoride produced at the Hanford Site during the Cold War[2][3]
Names
IUPAC name Plutonium(IV) fluoride
Other names Plutonium tetrafluoride
Identifiers
CAS Number	13709-56-3 N
3D model (JSmol)	Interactive image
ChemSpider	123078
PubChem CID	139558
CompTox Dashboard (EPA)	DTXSID90160061
InChI InChI=1S/4FH.Pu/h4*1H;/q;;;;+4/p-4 Key: USCBBUFEOOSGAJ-UHFFFAOYSA-J
SMILES F[Pu](F)(F)F
Properties
Chemical formula	PuF4
Molar mass	320 g/mol
Appearance	reddish-brown monoclinic crystals
Density	7.1 g/cm3
Melting point	1,027 °C (1,881 °F; 1,300 K)
Structure
Crystal structure	Monoclinic, mS60
Space group	C12/c1, No. 15
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Formation

Plutonium(IV) fluoride is produced in the reaction between plutonium dioxide (PuO₂) or plutonium(III) fluoride (PuF₃) with hydrofluoric acid (HF) in a stream of oxygen (O₂) at 450 to 600 °C. The main purpose of the oxygen stream is to avoid reduction of the product by hydrogen gas, small amounts of which are often found in HF.^[6]

PuO₂ + O₂ + 4 HF → PuF₄ + O₂ + 2 H₂O

4 PuF₃ + O₂ + 4 HF → 4 PuF₄ + 2 H₂O

Laser irradiation of plutonium hexafluoride (PuF₆) at wavelengths under 520 nm causes it to decompose into plutonium pentafluoride (PuF₅) and fluorine; if this is continued, plutonium(IV) fluoride is obtained.^[7]

Properties

In terms of its structure, solid plutonium(IV) fluoride features 8-coordinate Pu centers interconnected by doubly bridging fluoride ligands.^[8]

Reaction of plutonium tetrafluoride with barium, calcium, or lithium at 1200 °C give Pu metal:^[4][5][3]

PuF₄ + 2 Ba → 2 BaF₂ + Pu

PuF₄ + 2 Ca → 2 CaF₂ + Pu

PuF₄ + 4 Li → 4 LiF + Pu

Plutonium tetrafluoride sample with example of one color illustrated through reference to a color standard^[9]