Selenium tetrafluoride
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| ImageFile = Selenium-tetrafluoride-gas-3D-balls.png
| ImageSize = 200 px
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| Section1 = {{Chembox Identifiers
| CASNo = 13465-66-2
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| Section2 = {{Chembox Properties
| Formula = SeF<sub>4</sub>
| MolarMass = 154.954 g/mol
| Appearance = colourless liquid
| Density =
| MeltingPt = -10°C
| BoilingPt = 101°C
| Solubility =
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| Section3 = {{Chembox Hazards
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'''Selenium tetrafluoride''' ([[Selenium|Se]][[Fluorine|F<sub>4</sub>]]) is a [[chemical compound]]. It is a colourless liquid that reacts readily with water. It can be used as a fluorinating reagent in organic syntheses and has advantages over sulfur tetrafluoride in that milder conditions can be employed and it is a liquid rather than a gas. Selenium tetrafluoride was first synthesized by the reaction of [[selenium]] with [[fluorine]] by [[Paul Lebeau]] in 1907.<ref>{{cite journal
| title = Action of Fluorine on Selenium Tetrafluoride of Selenium
| author = [[Paul Lebeau]]
| journal = Comptes Rendus Acad. Sci., Paris
| year = 1907
| volume = 144
| issue =
| pages = 1042
| doi =
}}</ref>
:Se + 2 F<sub>2</sub> → SeF<sub>4</sub>
Other methods of preparation include fluorinating elemental selenium with [[chlorine trifluoride]]:
:3Se + ClF<sub>3</sub> → 3SeF<sub>4</sub> + 2Cl<sub>2</sub>
and reacting [[sulfur tetrafluoride]] wih [[selenium dioxide]]:
:SF<sub>4</sub> + SeO<sub>2</sub> → SeF<sub>4</sub> + SO<sub>2</sub>
Selenium in SeF<sub>4</sub> has an oxidation state of +4. Its shape in the gaseous phase is similar to that of SF<sub>4</sub> having a see-saw shape in accordance with VSEPR theory which predicts pseudo-trigonal pyramidal disposition of the five electron pairs around the selenium atom. The axial Se-F bond bonds are 177pm with an F-Se-F bond angle of 169.2°. The two other fluorine atoms are attached by shorter bonds (168pm), with an F-Se-F bond angle of 100.6°. In solution at low concentrations this monomeric structure predominates but at higher concentrations there is evidence for weak association between SeF<sub>4</sub> molecules leading to a distorted octahedral coordination around the sulfur atom. In the solid the sulfur atom also has a distorted octahedral environment.<br />
In HF SeF<sub>4</sub> is a weak base, weaker than [[sulfur tetrafluoride]], SF<sub>4</sub> (K<sub>b</sub>= 2 X 10<sup><nowiki>−</nowiki>2</sup>):
:SeF<sub>4</sub> + HF → SeF<sub>3</sub><sup>+</sup> + HF<sub>2</sub><sup><nowiki>−</nowiki></sup>; (K<sub>b</sub> = 4 X 10<sup><nowiki>−</nowiki>4</sup>)
Ionic adducts are formed with SbF<sub>5</sub>, AsF<sub>5</sub>, NbF<sub>5</sub>, TaF<sub>5</sub>, and BF<sub>3</sub> that contain the SeF<sub>3</sub><sup>+</sup> cation
<ref>{{cite journal
| title = Selenium tetrafluoride adducts. II. Adducts with boron trifluoride and some pentafluorides
| author = R. J. Gillespie and A. Whitla
| journal = Can. J. Chem.
| year = 1970
| volume = 48
| issue = 4
| pages = 657–663
| doi = 10.1139/cjc-48-4-657
}}</ref>.
With [[caesium fluoride]], CsF, the SeBr<sub>5</sub><sup><nowiki>−</nowiki></sup> anion is formed, which has a square pyramidal structure similar to the isoelectronic [[chlorine pentafluoride]], ClF<sub>5</sub> and [[bromine pentafluoride]], BrF<sub>5</sub>
<ref>{{cite journal
| title = Vibrational Spectra and Force Constants of the Square-Pyramidal Anions SF<sub>5</sub><sup><nowiki>−</nowiki></sup>, SeF<sub>5</sub><sup><nowiki>−</nowiki></sup>, and TeF<sub>5</sub><sup><nowiki>−</nowiki></sup>
| author = KO Christe, EC Curtis, CJ Schack, D Pilipovich
| journal = Inorganic Chemistry
| year = 1972
| volume = 11
| issue = 7
| pages = 1679
| doi =
}}</ref>
With 1,1,3,3,5,5-Hexamethylpiperidinium fluoride or 1,2-dimethylpropyltrimethylammonium fluoride the SeF<sub>6</sub><sup>2<nowiki>−</nowiki></sup> anion is formed. This has a distorted octahedral shape which contrasts to the regular octahedral shape of the analogous SeCl<sub>6</sub><sup>2<nowiki>−</nowiki></sup>
<ref>{{cite journal
| title = Reactions of the Naked Fluoride Ion: Syntheses and Structures of SeF<sub>6</sub><sup>2<nowiki>−</nowiki></sup> and BrF<sub>6</sub><sup><nowiki>−</nowiki></sup>
| author =Ali Reza Mahjoub, Xiongzhi Zhang, Konrad Seppelt
| journal = Chemistry - A European Journal
| year = 1995
| volume = 1
| issue = 4
| pages = 216
| doi = 10.1002/chem.19950010410
}}</ref>.
==References==
* ''Selenium: Inorganic Chemistry'' Krebs. B., Bonmann S., Eidenschink I.; Encyclopedia of Inorganic Chemistry (1994) John Wiley and Sons ISBN 0-471-93620-0
<div class="references-small">
<references/>
<!-- *{{cite journal
| title = On selenium tetrafluoride
| author = Edmund Brydges Rudhall Prideaux and Charles Beresford Cox
| journal = [[Journal of the Chemical Society]]
| year = 1928
| volume =
| issue =
| pages = 1603
| doi = 10.1039/JR9280001603
}}
*{{cite journal
| title = The preparation and properties of selenium tetrafluoride and oxyfluoride
| author = E. E. Aynsley, R. D. Peacock and P. L. Robinson
| journal = [[Journal of the Chemical Society]]
| year = 1952
| volume =
| issue =
| pages = 1231
| doi = 10.1039/JR9520001231
}}
*{{cite journal
| title = Some properties of selenium tetrafluoride
| author = R. D. Peacock
| journal = [[Journal of the Chemical Society]]
| year = 1953
| volume =
| issue =
| pages = 3617
| doi = 10.1039/JR9530003617
}}
*{{cite journal
| title = Structure of Selenium Tetrafluoride
| author = H. J. M. Bowen
| journal = [[Nature |Nature (journal)]]
| year = 1953
| volume = 172
| issue = 4369
| pages = 131–172
| doi = 10.1038/172171a0
}}
*{{cite journal
| title = Structure of Selenium Tetrafluoride
| author = F. Lachman
| journal = [[Nature |Nature (journal)]]
| year = 1953
| volume = 172
| issue = 4376
| pages = 467–510
| doi = 10.1038/172499a0
}}
*{{cite journal
| title = Investigation by electron diffraction of the molecular structures of sulphur hexafluoride, sulphur tetrafluoride, selenium hexafluoride and selenium tetrafluoride
| author = V. C. Ewing, L. E. Sutton
| journal = Transactions of the Faraday Society
| year = 1963
| volume = 59
| issue =
| pages = 1241
| doi = 10.1039/TF9635901241
}}
</div> -->
[[Category:Fluorides]]
[[Category:Selenium compounds]]
[[Category:Inorganic compound stubs]]
{{inorganic-compound-stub}}
[[ar:رباعي فلوريد سيلينيوم]]