xenon hexafluoride

Xenon hexafluoride can be prepared by heating of XeF₂ at about 300 °C under 6 MPa (60 atmospheres) of fluorine. With Nickel(II) fluoride as catalyst, however, this reaction can proceed at 120 °C even in xenon-fluorine molar ratios as low as 1:5.{{cite journal

| author = Melita Tramšek

| author2 = Boris Žemva

| title = Synthesis, Properties and Chemistry of Xenon(II) Fluoride

| date = December 5, 2006

| journal = Acta Chim. Slov.

| volume = 53

| issue = 2

| pages = 105–116

| doi = 10.1002/chin.200721209

| url = http://acta.chem-soc.si/53/53-2-105.pdf

| access-date = July 10, 2009

| archive-date = May 12, 2013

| archive-url = https://web.archive.org/web/20130512234432/http://acta.chem-soc.si/53/53-2-105.pdf

| url-status = dead

}}{{cite book|chapter=Xenon Hexafluoride|doi=10.1002/9780470132395.ch68|isbn=9780470132395|pages=258–260|year=2007|last1=Chernic|first1=C. L.|last2=Malm|first2=J. G.|title=Inorganic Syntheses|volume=VIII}}

The structure of XeF₆ required several years to establish in contrast to the cases of {{chem|XeF|2}} and {{chem|XeF|4}}. In the gas phase the compound is monomeric. VSEPR theory predicts that due to the presence of six fluoride ligands and one lone pair of electrons the structure lacks perfect octahedral symmetry, and indeed electron diffraction combined with high-level calculations indicate that the compound's point group is C_3v. It is a fluxional molecule. O_h is only insignificantly higher, indicating that the minimum on the energy surface is very shallow.{{cite journal|last = Seppelt|first = Konrad|date=June 1979|title = Recent Developments in the Chemistry of Some Electronegative Elements|journal = Accounts of Chemical Research|volume = 12|issue = 6|pages = 211–216|doi = 10.1021/ar50138a004}}

¹²⁹Xe and ¹⁹F NMR spectroscopy indicates that in solution the compound assumes a tetrameric structure: four equivalent xenon atoms are arranged in a tetrahedron surrounded by a fluctuating array of 24 fluorine atoms that interchange positions in a "cogwheel mechanism".

Six polymorphs of {{chem|XeF|6}} are known.{{Cite journal | first1 = S. |last1= Hoyer | first2 = K. | last2 = Emmler | first3 = T. | last3 = Seppelt| title = The structure of xenon hexafluoride in the solid state| journal = Journal of Fluorine Chemistry | volume = 127 | issue = 10| pages = 1415–1422| issn = 0022-1139 | doi = 10.1016/j.jfluchem.2006.04.014 | date = October 2006|bibcode= 2006JFluC.127.1415H }} including one that contains XeF{{su|b=5|p=+}} ions with bridging F{{su|p=−}} ions.{{cite book|title = Inorganic Chemistry|url = https://archive.org/details/inorganicchemist00jeho|url-access = limited|author = James E. House|publisher = Academic Press|year = 2008|isbn = 978-0-12-356786-4|page = [https://archive.org/details/inorganicchemist00jeho/page/n583 569]}}

Xenon hexafluoride hydrolyzes, ultimately affording xenon trioxide:{{cite journal | last = Appelman | first = E. H. |author2=J. G. Malm |date=June 1964 | title = Hydrolysis of Xenon Hexafluoride and the Aqueous Solution Chemistry of Xenon | journal = Journal of the American Chemical Society | volume = 86 | issue = 11 | pages = 2141–2148 | doi = 10.1021/ja01065a009}}

:XeF₆ + H₂O → XeOF₄ + 2 HF

:XeOF₄ + H₂O → XeO₂F₂ + 2 HF

:XeO₂F₂ + H₂O → XeO₃ + 2 HF

:XeF₆ + 3 H₂O → XeO₃ + 6 HF

XeF₆ is a Lewis acid, binding one and two fluoride anions:

:XeF₆ + F⁻ → XeF{{su|b=7|p=−}}

:XeF{{su|b=7|p=−}} + F⁻ → XeF{{su|b=8|p=2−}}

Salts of the octafluoroxenate(VI) anion (XeF{{su|b=8|p=2−}}) are very stable, decomposing only above 400 °C.{{cite book

| title = Comprehensive Inorganic Chemistry

| first1 = Sulekh

| last1 = Chandra

| publisher = New Age International

| year = 2004

| isbn = 81-224-1512-1

| page = 308

}} This anion has been shown to have square antiprismatic geometry, based on single-crystal X-ray counter analysis of its nitrosonium salt, Nitrosonium octafluoroxenate(VI).{{Cite journal | first3 = A.| first2 = H. | first4 = M.| title = Antiprismatic Coordination about Xenon: the Structure of Nitrosonium Octafluoroxenate(VI)| first1 = W.| last2 = Holloway| last3 = Coyle| volume = 173| journal = Science| issue = 4003| pages = 1238–1239| issn = 0036-8075| doi = 10.1126/science.173.4003.1238| last4 = Williams| pmid = 17775218| last1 = Peterson| date = September 1971|bibcode = 1971Sci...173.1238P | s2cid = 22384146 }} The sodium and potassium salts are formed directly from sodium fluoride and potassium fluoride:

:2 NaF + {{chem|XeF|6}} → {{chem|Na|2|XeF|8}}

:2 KF + {{chem|XeF|6}} → {{chem|K|2|XeF|8}}

These are thermally less stable than the caesium and rubidium salts, which are synthesized by first forming the heptafluoroxenate salts:

:CsF + {{chem|XeF|6}} → Caesium heptafluoroxenate

:RbF + {{chem|XeF|6}} → {{chem|RbXeF|7}}

which are then pyrolysed at 50 °C and 20 °C, respectively, to form the yellow{{cite encyclopedia

| year = 1995

| title = Xenon

| encyclopedia = Encyclopædia Britannica

| publisher = Encyclopædia Britannica Inc.

| location =

| id =

}} octafluoroxenate salts:{{cite book

| last1 = Holleman

| first1 = A. F.

| last2 = Wiberg

| first2 = E.

| title = Inorganic Chemistry

| publisher = Academic Press

| location = San Diego

| year = 2001

| isbn = 0-12-352651-5

}}{{cite book

| title = Anorganische Chemie

| url = https://archive.org/details/anorganischechem00ried

| url-access = limited

| first1 = Erwin

| last1 = Riedel

| first2 = Christoph

| last2 = Janiak

| edition = 7th

| publisher = Walter de Gruyter

| year = 2007

| isbn = 978-3-11-018903-2

| page = [https://archive.org/details/anorganischechem00ried/page/n409 393]

}}

:2 {{chem|CsXeF|7}} → {{chem|Cs|2|XeF|8}} + {{chem|XeF|6}}

:2 {{chem|RbXeF|7}} → {{chem|Rb|2|XeF|8}} + {{chem|XeF|6}}

These salts are hydrolysed by water, yielding various products containing xenon and oxygen.

The two other binary fluorides of xenon do not form such stable adducts with fluoride.

{{chem|XeF|6}} reacts with strong fluoride acceptors such as {{chem|RuF|5}} and {{chem|BrF|3|·AuF|3}}{{cite book

| title = Advanced Inorganic Chemistry

| edition = 6th

| author = Cotton

| publisher = Wiley-India

| year = 2007

| isbn = 978-81-265-1338-3

| page = 591

}} to form the XeF{{su|b=5|p=+}} cation:

:{{chem|XeF|6}} + {{chem|RuF|5}} → XeF{{su|b=5|p=+}}RuF{{su|b=6|p=−}}

:{{chem|XeF|6}} + {{chem|BrF|3|·AuF|3}} → XeF{{su|b=5|p=+}}AuF{{su|b=4|p=−}} + {{chem|BrF|3}}

{{reflist}}

• [http://webbook.nist.gov/cgi/cbook.cgi?ID=C13693099 WebBook page for XeF₆]

{{Hexafluorides}}

{{Xenon compounds}}

{{Noble gas compounds}}

{{fluorine compounds}}

Category:Xenon(VI) compounds

Category:Hexafluorides

Category:Nonmetal halides

Category:Fluorinating agents

Category:Gases with color