- Selenium tetrafluoride
Chembox new
ImageFile = Selenium-tetrafluoride-gas-3D-balls.png
ImageSize = 200 px
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Section1 = Chembox Identifiers
CASNo = 13465-66-2
PubChem =
SMILES =
Section2 = Chembox Properties
Formula = SeF4
MolarMass = 154.954 g/mol
Appearance = colourless liquid
Density =
MeltingPt = -10°C
BoilingPt = 101°C
Solubility =
Section7 = Chembox Hazards
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FlashPt =
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NFPA 704
NFPA-H = 3
NFPA-F = ?
NFPA-R = 2
NFPA-O = WSelenium tetrafluoride (SeF4) 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 ofselenium withfluorine byPaul Lebeau in 1907. [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 = ]:Se + 2 F2 → SeF4Other methods of preparation include fluorinating elemental selenium with
chlorine trifluoride ::3Se + ClF3 → 3SeF4 + 2Cl2and reactingsulfur tetrafluoride wihselenium dioxide ::SF4 + SeO2 → SeF4 + SO2Selenium in SeF4 has an oxidation state of +4. Its shape in the gaseous phase is similar to that of SF4 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 SeF4 molecules leading to a distorted octahedral coordination around the sulfur atom. In the solid the sulfur atom also has a distorted octahedral environment.
In HF SeF4 is a weak base, weaker thansulfur tetrafluoride , SF4 (Kb= 2 X 10− 2)::SeF4 + HF → SeF3+ + HF2− ; (Kb = 4 X 10− 4)Ionic adducts are formed with SbF5, AsF5, NbF5, TaF5, and BF3 that contain the SeF3+ cation [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] .Withcaesium fluoride , CsF, the SeBr5− anion is formed, which has a square pyramidal structure similar to the isoelectronicchlorine pentafluoride , ClF5 andbromine pentafluoride , BrF5 [cite journal
title = Vibrational Spectra and Force Constants of the Square-Pyramidal Anions SF5− , SeF5− , and TeF5−
author = KO Christe, EC Curtis, CJ Schack, D Pilipovich
journal = Inorganic Chemistry
year = 1972
volume = 11
issue = 7
pages = 1679
doi = ] With 1,1,3,3,5,5-Hexamethylpiperidinium fluoride or 1,2-dimethylpropyltrimethylammonium fluoride the SeF62− anion is formed. This has a distorted octahedral shape which contrasts to the regular octahedral shape of the analogous SeCl62− [cite journal
title = Reactions of the Naked Fluoride Ion: Syntheses and Structures of SeF62− and BrF6−
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 ] .References
* "Selenium: Inorganic Chemistry" Krebs. B., Bonmann S., Eidenschink I.; Encyclopedia of Inorganic Chemistry (1994) John Wiley and Sons ISBN 0-471-93620-0
External links
* [http://webbook.nist.gov/cgi/cbook.cgi?ID=C13465662 WebBook page for SeF4]
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