Selenium tetrafluoride 5296809 215692859 2008-05-29T08:24:25Z DOI bot 6652755 Citation maintenance. Initiated by [[User:Tarun2k|Tarun2k]]. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. {{Chembox new | ImageFile = Selenium-tetrafluoride-gas-3D-balls.png | ImageSize = 200 px | IUPACName = | OtherNames = | Section1 = {{Chembox Identifiers | CASNo = 13465-66-2 | PubChem = | SMILES = }} | Section2 = {{Chembox Properties | Formula = SeF<sub>4</sub> | MolarMass = 154.954 g/mol | Appearance = colourless liquid | Density = | MeltingPt = -10°C | BoilingPt = 101°C | Solubility = }} | Section3 = {{Chembox Hazards | MainHazards = | FlashPt = | Autoignition = }} }} '''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>&minus;</nowiki>2</sup>): :SeF<sub>4</sub> + HF → SeF<sub>3</sub><sup>+</sup> + HF<sub>2</sub><sup><nowiki>&minus;</nowiki></sup>; (K<sub>b</sub> = 4 X 10<sup><nowiki>&minus;</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>&minus;</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>&minus;</nowiki></sup>, SeF<sub>5</sub><sup><nowiki>&minus;</nowiki></sup>, and TeF<sub>5</sub><sup><nowiki>&minus;</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>&minus;</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>&minus;</nowiki></sup> <ref>{{cite journal | title = Reactions of the Naked Fluoride Ion: Syntheses and Structures of SeF<sub>6</sub><sup>2<nowiki>&minus;</nowiki></sup> and BrF<sub>6</sub><sup><nowiki>&minus;</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]]