Antimony pentafluoride
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2008-07-06T00:52:08Z
Mild Bill Hiccup
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| ImageFileL1 = Antimony-pentafluoride-2D.png
| ImageSizeL1 = 120px
| ImageNameL1 = Antimony pentafluoride
| ImageFileR1 = Antimony-pentafluoride-monomer-3D-balls.png
| ImageSizeR1 = 120px
| ImageNameR1 = Antimony pentafluoride
| IUPACName = antimony(V) fluoride
| OtherNames = antimony pentafluoride<br>pentafluoroantimony
| Section1 = {{Chembox Identifiers
| CASNo = 7783-70-2
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| Section2 = {{Chembox Properties
| Formula = SbF<sub>5</sub>
| MolarMass = 216.74 g mol<sup>−1</sup>
| Appearance =
| Density = 4.07 g cm<sup>-3</sup>
| MeltingPt = 8.3 °C (281.3 K)
| BoilingPt = 141 °C (414 K)
| Solubility = Reacts with water}}
| SolubleOther =
| Solvent = [[Sulfur dioxide|SO<sub>2</sub>]], [[Sulfuryl chloride fluoride|SO<sub>2</sub>FCl]]
| Section3 = {{Chembox Hazards
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| Section7 = {{Chembox Hazards
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| NFPA-H = 4
| NFPA-F = 0
| NFPA-R = 1
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'''Antimony pentafluoride''' is the [[chemical compound]] with the formula [[Antimony|Sb]][[Fluorine|F]]<sub>5</sub>. This colourless, viscous liquid is a valuable [[Lewis acid]] and a component of the [[superacid]] [[fluoroantimonic acid]], the strongest known acid. Some features that give the compound scientific interest are its [[Lewis acid]]ity and that it also reacts with almost all known compounds.<ref>Olah, G. A.; Prakash, G. K. S.; Wang, Q.; Li, X.-y."Antimony(V) Fluoride" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.</ref>
==Structure and chemical reactions==
In the gas phase, SbF<sub>5</sub> adopts a trigonal bipyramidal structure of D<sub>3h</sub> [[symmetry group|point group symmetry]] (see picture). The structure is more complex in the liquid and solid state. The liquid contains polymers wherein each Sb is octahedral, the structure being described with the formula [SbF<sub>4</sub>(μ-F)<sub>2</sub>]<sub>n</sub>. The crystalline material is tetrameric, i.e. it has the formula [SbF<sub>4</sub>(μ-F)]<sub>4</sub>. The Sb-F bonds are 2.02 Å within the eight-membered Sb<sub>4</sub>F<sub>4</sub> ring; the remaining fluoride ligands radiating from the four Sb centers are shorter at 1.82 Å.<ref>Edwards, A. J.; Taylor, P. "Crystal structure of Antimony Pentafluoride" Journal of the Chemical Society, Chemical Communications 1971, pp. 1376-7.{{DOI|10.1039/C29710001376}}</ref> The related species PF<sub>5</sub> and AsF<sub>5</sub> are [[monomer]]ic in the solid and liquid states, probably due to the smaller sizes of the central atom, which limits their coordination number. BiF<sub>5</sub> is a polymer.<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.</ref>
SbF<sub>5</sub> is a strong Lewis acid, exceptionally so toward sources of F<sup>−</sup> to give the very stable anion [SbF<sub>6</sub>]<sup>−</sup>. The latter reacts with additional SbF<sub>5</sub> to give [Sb<sub>2</sub>F<sub>11</sub>]<sup>−</sup>.
In the same way that SbF<sub>5</sub> enhances the [[Brønsted-Lowry acid|Brønsted acidity]] of HF, it enhances the [[oxidation|oxidizing]] power of F<sub>2</sub>. This effect is illustrated by the oxidation of [[oxygen]]:<ref>Shamir, J.; Binenboym, J. "Dioxygenyl Salts" Inorganic Syntheses, 1973, XIV, 109-122. {{ISSN|0073-8077}}</ref>
:SbF<sub>5</sub> + ½F<sub>2</sub> + O<sub>2</sub> → [O<sub>2</sub>]<sup>+</sup>[SbF<sub>6</sub>]<sup>-</sup>
Antimony pentafluoride has also been used in the first discovered chemical reaction that produces [[fluorine]] gas from fluoride compounds:
:2 SbF<sub>5</sub> + [[Potassium|K]]<sub>2</sub>[[Manganese|Mn]]F<sub>6</sub> → 2 KSbF<sub>6</sub> + MnF<sub>3</sub> + 0.5 F<sub>2</sub>
The driving force for this reactions is the high affinity of SbF<sub>5</sub> for F<sup>-</sup>, which is the same property which recommends the use of SbF<sub>5</sub> to generate superacids.
==Safety==
SbF<sub>5</sub> reacts violently with many compounds, often releasing dangerous [[hydrogen fluoride]].
==References==
{{reflist}}
<div class="references-small">
*IPCS, CEC 2005. [http://www.inchem.org/documents/icsc/icsc/eics0220.htm "ANTIMONY PENTAFLUORIDE (ICSC)] Retrieved [[May 13]], [[2006]].
*Barbalace, Kenneth. [http://environmentalchemistry.com/yogi/chemicals/cn/Antimony%A0Pentafluoride.html "Chemical Database - Antimony Pentafluoride"]. 1995 - 2006. Retrieved May 13, 2006.
</div>
==External links==
*[http://www.npi.gov.au/database/substance-info/profiles/10.html National Pollutant Inventory - Antimony and compounds fact sheet]
*[http://www.npi.gov.au/database/substance-info/profiles/44.html National Pollutant Inventory - Fluoride compounds fact sheet]
[[Category:Superacids]]
[[Category:Antimony compounds]]
[[Category:Fluorides]]
{{inorganic-compound-stub}}
[[ar:فلوريد أنتيموان خماسي]]
[[cs:Fluorid antimoničný]]
[[de:Antimon(V)-fluorid]]
[[ja:五フッ化アンチモン]]
[[pl:Pentafluorek antymonu]]
[[pt:Pentafluoreto de antimônio]]
[[fi:Antimonipentafluoridi]]
[[zh:五氟化锑]]