View source for Selenium hexafluoride

{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 432484439
| ImageFileL1 = Selenium-hexafluoride-2D.png
| ImageSizeL1 = 
| ImageFileR1 = Selenium-hexafluoride-3D-balls.png
| ImageSizeR1 = 
| IUPACName = Selenium hexafluoride
| OtherNames = Selenium(VI) fluoride, Selenium fluoride
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|??}}
| CASNo = 7783-79-1
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = H91D37I668
| PubChem = 24558
| RTECS = VS9450000
|  ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}
| ChemSpiderID = 22964
|  InChIKey = LMDVZDMBPZVAIV-UHFFFAOYAP
|  StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 1S/F6Se/c1-7(2,3,4,5)6
|  StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = LMDVZDMBPZVAIV-UHFFFAOYSA-N
| SMILES = F[Se](F)(F)(F)(F)F
| InChI = 1S/F6Se/c1-7(2,3,4,5)6
}}
|Section2={{Chembox Properties
| Formula = SeF<sub>6</sub>
| MolarMass = 192.9534 g/mol
| Appearance = colourless gas
| Density = 7.887 g/L<ref name=CRC>{{RubberBible86th}}</ref>
| MeltingPtC = -39
| BoilingPtC = -34.5
| BoilingPt_notes =  sublimes
| Solubility = insoluble
| RefractIndex = 1.895
| VaporPressure = >1 atm (20°C)<ref name=PGCH/>
| MagSus = &minus;51.0·10<sup>−6</sup> cm<sup>3</sup>/mol
}}
|Section3={{Chembox Structure
| CrystalStruct = [[Orthorhombic]], [[Pearson symbol|oP28]]
| SpaceGroup = Pnma, No. 62
| Coordination = octahedral (''O<sub>h</sub>'')
| Dipole = 0 
}}
|Section7={{Chembox Hazards
| MainHazards = toxic, corrosive
| FlashPt = 
| NFPA-H = 3
| NFPA-F = 0
| NFPA-R = 0
| AutoignitionPt = 
| IDLH = 2 ppm<ref name=PGCH>{{PGCH|0551}}</ref>
| REL = TWA 0.05 ppm<ref name=PGCH/>
| PEL = TWA 0.05 ppm (0.4 mg/m<sup>3</sup>)<ref name=PGCH/> 
| LCLo = 10 ppm (rat, 1 hr)<br/>10 ppm (mouse, 1 hr)<br/>10 ppm (guinea pig, 1 hr)<ref>{{IDLH|7783791|Selenium hexafluoride}}</ref>
}}
|Section4={{Chembox Thermochemistry
| DeltaHf = −1030 kJ/mol<ref name = "Wiberg&Holleman">{{ cite book |author1=Wiberg, E. |author2=Holleman, A. F. | title = Inorganic Chemistry | year = 2001 | publisher = Elsevier | isbn = 0-12-352651-5 }}</ref>
| DeltaHc = 
| Entropy = 
| HeatCapacity = 
 }}
}}

'''Selenium hexafluoride''' is the [[inorganic compound]] with the [[chemical formula|formula]] SeF<sub>6</sub>. It is a very toxic colourless gas described as having a "repulsive" odor.<ref name="decompose">{{ cite web | url = http://www.cpcb.nic.in/divisionsofheadoffice/pci-ssi/MATERIAL_SAFETY-DATABASE/MSDS2008/558.pdf | title = Material Safety | access-date = 2010-07-24 }}</ref> It is not widely encountered and has no commercial applications.<ref>{{ Ullmann | author = Langner, B. E. | title = Selenium and Selenium Compounds | doi = 10.1002/14356007.a23_525 }}</ref>

==Structure, preparation, and reactions==
SeF<sub>6</sub> has [[octahedral molecular geometry]] with an Se&minus;F bond length of 168.8 [[picometer|pm]].  In terms of bonding, it is [[hypervalent molecule|hypervalent]].

SeF<sub>6</sub> can be prepared from the elements.<ref>{{ Cite book |author1=Yost, D. M. |author2=Simons, J. H. |title=Inorganic Syntheses | chapter = Sulfur, Selenium, and Tellurium Hexafluorides | year = 1939 | volume = 1 | pages = 121–122 | doi = 10.1002/9780470132326.ch44 |isbn=9780470132326 }}</ref>  It also forms by the reaction of [[bromine trifluoride]] (BrF<sub>3</sub>) with [[selenium dioxide]].  The crude product can be purified by sublimation.

The relative reactivity of the hexafluorides of S, Se, and Te follows the order [[tellurium hexafluoride|TeF<sub>6</sub>]] > SeF<sub>6</sub> > [[sulfur hexafluoride|SF<sub>6</sub>]], the latter being completely inert toward hydrolysis until high temperatures. SeF<sub>6</sub> also resists hydrolysis.<ref name = "Wiberg&Holleman"/>  The gas can be passed through 10% NaOH or KOH without change, but reacts with gaseous [[ammonia]] at 200&nbsp;°C.<ref name = "Krebs">{{ cite encyclopedia |author1=Krebs, B. |author2=Bonmann, S. |author3=Eidenschink, I. | title = Selenium-Inorganic Chemistry | encyclopedia = Encyclopedia of Inorganic Chemistry | editor = King, R. B.  | year = 1994 | publisher = John Wiley & Sons | isbn = 0-471-93620-0 }}</ref>

==Safety==
Although selenium hexafluoride is quite inert and slow to hydrolyze, it is toxic even at low concentrations,<ref name="toxic">{{cite web | url = http://www.atsdr.cdc.gov/MMG/MMG.asp?id=1015&tid=215 | archive-url = https://web.archive.org/web/20100528071037/http://www.atsdr.cdc.gov/MMG/MMG.asp?id=1015&tid=215 | url-status = dead | archive-date = May 28, 2010 | title = Medical Management Guidelines for Selenium Hexafluoride (SeF<sub>6</sub>) | publisher = CDC ATSDR | access-date = 2010-07-24 }}</ref> especially by longer exposure. In the U.S., [[Occupational Safety and Health Administration|OSHA]] and [[ACGIH]] standards for selenium hexafluoride exposure is an upper limit of 0.05&nbsp;ppm in air averaged over an eight-hour work shift. Additionally, selenium hexafluoride is designated as [[Immediately Dangerous to Life and Health|IDLH]] chemical with a maximum allowed exposure limit of 2 ppm.<ref>[https://www.cdc.gov/niosh/idlh/7783791.html Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs)]</ref>

==References==
{{reflist}}

==External links==
* [https://www.atsdr.cdc.gov/toxfaqs/tfacts183.pdf ATSDR ToxFAQs - Selenium Hexafluoride] U.S. [[Department of Health and Human Services]]
* [https://www.cdc.gov/niosh/npg/npgd0551.html CDC - NIOSH Pocket Guide to Chemical Hazards] U.S. [[Department of Health and Human Services]]
* [http://webbook.nist.gov/cgi/cbook.cgi?ID=C7783791 WebBook page for SeF<sub>6</sub>]

{{Hexafluorides}}
{{Selenium compounds}}
{{fluorine compounds}}

[[Category:Selenium(VI) compounds]]
[[Category:Hexafluorides]]
[[Category:Octahedral compounds]]
[[Category:Chalcohalides]]
[[Category:Selenium halides]]
[[Category:Foul-smelling chemicals]]