View source for Chemistry:Organoxenon chemistry

{{Short description|Study of compounds containing xenon-carbon bonds}}
'''Organoxenon chemistry''' is the study of the properties of '''organoxenon compounds''', which contain [[Chemistry:Carbon|carbon]] to [[Chemistry:Xenon|xenon]] chemical bonds. The first organoxenon compounds were divalent, such as (C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>Xe. The first tetravalent organoxenon compound, [C<sub>6</sub>F<sub>5</sub>XeF<sub>2</sub>][BF<sub>4</sub>], was synthesized in 2004.<ref name = XeIV>{{cite journal|last1=LeBlond|first1=Nicolas|last2=Lutar|first2=Karel|last3=Žemva|first3=Boris|title=The First Organoxenon(IV) Compound: Pentafluorophenyldifluoroxenonium(IV) Tetrafluoroborate|journal=Angewandte Chemie International Edition|date=2000-01-16|volume=39|issue=2|pages=391–393|doi=10.1002/(SICI)1521-3773(20000117)39:2<391::AID-ANIE391>3.0.CO;2-U|pmid=10649421 }}</ref> So far, more than one hundred organoxenon compounds have been researched.

Most of the organoxenon compounds are more unstable than xenon fluorides due to the high [[Chemistry:Chemical polarity|polarity]]. The molecular dipoles of xenon difluoride and [[Chemistry:Xenon tetrafluoride|xenon tetrafluoride]] are both 0&nbsp;[[Debye|D]]. The early synthesized ones only contain perfluoro groups, but later some other groups were found, e.g. 2,4,6-trifluorophenyl.<ref name=XeII>{{cite journal|title=C<sub>6</sub>F<sub>5</sub>XeF, a versatile starting material in xenon-carbon chemistry|journal=Journal of Fluorine Chemistry|date=2004-05-31|volume=125|issue=6|pages=981–988|doi=10.1016/j.jfluchem.2004.01.019|last=Frohn|first=H.}}</ref>

== Organoxenon(II) compounds ==
The most common bivalent organoxenon compound is C<sub>6</sub>F<sub>5</sub>XeF, which is almost always used as a precursor to other organoxenon compounds. Due to the instability of xenon(II), it is difficult to synthesize organoxenon compounds by using general organic reagents. Organoxenon compounds are frequently prepared from organocadmium species including Cd(Ar<sub>F</sub>)<sub>2</sub> (where Ar<sub>F</sub> is a fluorine-containing arene), C<sub>6</sub>F<sub>5</sub>SiF<sub>3</sub>, and C<sub>6</sub>F<sub>5</sub>SiMe<sub>3</sub> (used along with fluoride).

With the use of stronger [[Chemistry:Lewis acid|Lewis acid]]s, such as C<sub>6</sub>F<sub>5</sub>BF<sub>2</sub>, [[Physics:Ionic compound|ionic compound]]s like [RXe][Ar<sub>F</sub>BF<sub>3</sub>] can be produced. Alkenyl and [[Chemistry:Alkyl|alkyl]] organoxenon compounds are prepared in this way as well, for example, C<sub>6</sub>F<sub>5</sub>XeCF=CF<sub>2</sub> and C<sub>6</sub>F<sub>5</sub>XeCF<sub>3</sub>.<ref name=XeII />

Some typical reactions are listed below:

:2&nbsp;C<sub>6</sub>F<sub>5</sub>XeF + Cd(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> → 2&nbsp;Xe(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> + CdF<sub>2</sub>↓

:C<sub>6</sub>F<sub>5</sub>XeF + (CH<sub>3</sub>)<sub>3</sub>SiCN → C<sub>6</sub>F<sub>5</sub>XeCN + (CH<sub>3</sub>)<sub>3</sub>SiF

:2&nbsp;C<sub>6</sub>F<sub>5</sub>XeF + Cd(2,4,6-F<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)<sub>2</sub> → 2&nbsp;(2,4,6-F<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)XeC<sub>6</sub>F<sub>5</sub> + CdF<sub>2</sub>↓

The third reaction also produces (C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>Xe, Xe(2,4,6-F<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)<sub>2</sub> and so on.

The precursor C<sub>6</sub>F<sub>5</sub>XeF can be prepared by the reaction of trimethyl(pentafluorophenyl)silane (C<sub>6</sub>F<sub>5</sub>SiMe<sub>3</sub>) and [[Chemistry:Xenon difluoride|xenon difluoride]]. Adding fluoride to the adduct of C<sub>6</sub>F<sub>5</sub>XeF and [[Chemistry:Arsenic pentafluoride|arsenic pentafluoride]] is another method.<ref name=XeII />

Arylxenon compounds with fewer fluorine substituents are also known. For instance, (2,6-F<sub>2</sub>C<sub>6</sub>H<sub>3</sub>)Xe<sup>+</sup>{{chem|BF|4|-}} and (4-FC<sub>6</sub>H<sub>4</sub>)Xe<sup>+</sup>{{chem|BF|4|-}} have been prepared, and a crystal structure of the former has been obtained, consisting of a formally 1-coordinate xenon with a long, weak contact with a fluorine on the tetrafluoroborate anion.<ref>{{Cite journal|last1=Gilles|first1=T.|last2=Gnann|first2=R.|last3=Naumann|first3=D.|last4=Tebbe|first4=K. F.|date=1994-03-15|title=2,6-Difluorphenylxenon(II)-tetrafluoroborat|url=http://scripts.iucr.org/cgi-bin/paper?S0108270193009898|journal=Acta Crystallographica Section C|language=en|volume=50|issue=3|pages=411–413|doi=10.1107/s0108270193009898|issn=0108-2701}}</ref><ref>{{Cite journal|last1=Naumann|first1=D.|last2=Butler|first2=H.|last3=Gnann|first3=R.|last4=Tyrra|first4=W.|date=1993-03-01|title=Arylxenon tetrafluoroborates: compounds of unexpected stability|journal=Inorganic Chemistry|language=English|volume=32|issue=6|pages=861–863|doi=10.1021/ic00058a018|issn=0020-1669}}</ref>

== Organoxenon(IV) compounds ==
In 2000, Karel Lutar and Boris Žemva ''et al.'' produced an ionic compound. They treated [[Chemistry:Xenon tetrafluoride|xenon tetrafluoride]] and difluoro(pentafluorophenyl)borane in [[Chemistry:Dichloromethane|dichloromethane]] at −55&nbsp;°C:

:XeF<sub>4</sub> + C<sub>6</sub>F<sub>5</sub>BF<sub>2</sub> {{overset|DCM|→}} [C<sub>6</sub>F<sub>5</sub>XeF<sub>2</sub>]<sup>+</sup>{{chem|BF|4|-}}

The compound is an extremely strong fluorinating agent, and it is capable of converting (C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>P to (C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>PF<sub>2</sub>, C<sub>6</sub>F<sub>5</sub>I to C<sub>6</sub>F<sub>5</sub>IF<sub>2</sub>, and iodine to [[Chemistry:Iodine pentafluoride|iodine pentafluoride]].<ref name = XeIV />

== References ==
{{reflist}}

{{Xenon compounds}}
{{Noble gas compounds}}
{{ChemicalBondsToCarbon}}

[[Category:Xenon compounds|*]]

{{Sourceattribution|Organoxenon chemistry}}