Krypton difluoride

Krypton difluoride
Skeletal formula of krypton difluoride with a dimension	Spacefill model of 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.^[2] 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 Kr
₂F⁺
₃ cations.^[3]

The atomization energy of KrF₂ (KrF_2(g) → Kr_(g) + 2 F_(g)) is 21.9 kcal/mol, giving an average Kr–F bond energy of only 11 kcal/mol,^[4] 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 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.^[5] The formation of krypton difluoride is endothermic, with a heat of formation (gas) of 14.4 ± 0.8 kcal/mol measured at 93 °C.^[5]

^ R. D. Burbank, W. E. Falconer and W. A. Sunder (1972). "Crystal Structure of Krypton Difluoride at −80 °C". Science. 178 (4067): 1285–1286. doi:10.1126/science.178.4067.1285. PMID 17792123. S2CID 96692996.
^ Grosse, A. V.; Kirshenbaum, A. D.; Streng, A. G.; Streng, L. V. (1963). "Krypton Tetrafluoride: Preparation and Some Properties". Science. 139 (3559): 1047–8. Bibcode:1963Sci...139.1047G. doi:10.1126/science.139.3559.1047. PMID 17812982.
^ Cite error: The named reference Lehmann was invoked but never defined (see the help page).
^ The values of D_e(F–KrF) and D_e(F–Kr•) are estimated to be comparable, at ~10-12 kcal/mol, while ΔH(KrF⁺ → Kr⁺ + F•) is estimated to be ~42 kcal/mol.
^ ^a ^b Cockett, A. H.; Smith, K. C.; Bartlett, Neil (1973). The Chemistry of the Monatomic Gases: Pergamon Texts in Inorganic Chemistry. Pergamon Press. ISBN 978-0-08-018782-2.

[1] R. D. Burbank, W. E. Falconer and W. A. Sunder (1972). "Crystal Structure of Krypton Difluoride at −80 °C". Science. 178 (4067): 1285–1286. doi:10.1126/science.178.4067.1285. PMID 17792123. S2CID 96692996.

[2] Grosse, A. V.; Kirshenbaum, A. D.; Streng, A. G.; Streng, L. V. (1963). "Krypton Tetrafluoride: Preparation and Some Properties". Science. 139 (3559): 1047–8. Bibcode:1963Sci...139.1047G. doi:10.1126/science.139.3559.1047. PMID 17812982.

[Lehmann-3] Cite error: The named reference Lehmann was invoked but never defined (see the help page).

[4] The values of D_e(F–KrF) and D_e(F–Kr•) are estimated to be comparable, at ~10-12 kcal/mol, while ΔH(KrF⁺ → Kr⁺ + F•) is estimated to be ~42 kcal/mol.

[:0-5] Cockett, A. H.; Smith, K. C.; Bartlett, Neil (1973). The Chemistry of the Monatomic Gases: Pergamon Texts in Inorganic Chemistry. Pergamon Press. ISBN 978-0-08-018782-2.

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