Krypton difluoride

Krypton difluoride
Names
	IUPAC name Krypton difluoride
	Other names Krypton fluoride; Krypton(II) fluoride
Identifiers
CAS Number	13773-81-4 ;
3D model (JSmol)	Interactive image;
ChemSpider	75543 ;
PubChem CID	83721;
UNII	A91DJL4OJC ;
CompTox Dashboard (EPA)	DTXSID7065623 ;
	InChI InChI=1S/KrF2/c1-3-2 Key: QGOSZQZQVQAYFS-UHFFFAOYSA-N ; InChI=1/F2Kr/c1-3-2 Key: QGOSZQZQVQAYFS-UHFFFAOYAJ;
	SMILES F[Kr]F;
Properties
Chemical formula	F2Kr
Molar mass	121.795 g·mol−1
Appearance	Colourless crystals (solid)
Density	3.24 g cm−3 (solid)
Solubility in water	Reacts
Structure
Crystal structure	Body-centered tetragonal
Space group	P42/mnm, No. 136
Lattice constant	a = 0.4585 nm, c = 0.5827 nm
Molecular shape	Linear
Dipole moment	0 D
Related compounds
Related compounds	Xenon difluoride
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Krypton difluoride, KrF₂ is a chemical compound of krypton and fluorine. It was the first compound of krypton discovered. It is a volatile, colourless solid at room temperature. The structure of the KrF₂ molecule is linear, with Kr−F distances of 188.9 pm. It reacts with strong Lewis acids to form salts of the KrF⁺ and Kr₂F₃⁺ cations.

The atomization energy of KrF₂ (KrF₂(g) → Kr(g) + 2 F(g)) is 92 kJ/mol (21.9 kcal/mol), giving an average Kr–F bond energy of only 46 kJ/mol (11 kcal/mol), the weakest of any isolable fluoride. In comparison, the dissociation of difluorine to atomic fluorine requires cleaving a F–F bond with a bond dissociation energy of 150 kJ/mol (36 kcal/mol). Consequently, KrF₂ is a good source of the extremely reactive and oxidizing atomic fluorine. It is thermally unstable, with a decomposition rate of 10 % per hour at room temperature. The formation of krypton difluoride is endothermic, with a heat of formation (gas) of 57–64 kJ/mol (13.6–15.2 kcal/mol) measured at 93 °C.