Silver(II) fluoride 3139931 223053621 2008-07-02T10:47:43Z Puppy8800 5404759 iw {{Chembox new | Name = Silver(II) fluoride | ImageFile = Silver(II)-fluoride-3D-ionic.png <!-- | ImageSize = 200px --> | ImageName = Silver(II) fluoride | IUPACName = silver(II) fluoride | OtherNames = silver difluoride | Section1 = {{Chembox Identifiers | CASNo = 7775-41-9 }} | Section2 = {{Chembox Properties | Formula = AgF<sub>2</sub> | MolarMass = 145.865 g/mol | Appearance = white or grey crystalline powder, [[hygroscopic]] | Density = 4.58 g/cm<sup>3</sup> | Solubility = Decomposes, violently | MeltingPt = 690 °C (963 K) | BoilingPt = decomposes at 700 °C (973 K) }} | Section3 = {{Chembox Structure | MolShape = linear | Coordination = tetragonally elongated<br />octahedral coordination | CrystalStruct = orthorhombic }} | Section7 = {{Chembox Hazards | ExternalMSDS = [http://newsearchch.chemexper.com/cheminfo/servlet/org.dbcreator.MainServlet?action=PowerSearch&query=msds._msdsID%3D19659&sort=&target=msds&from=0&realQuery=rn.value%3D%3D%227783-95-1%22&searchTemplate=rn.value%3D%3D%3F&searchValue=7783-95-1&history=off&options=brandqtyoffer&format=ccd MSDS] | MainHazards = toxic, reacts violently<br />with water, powerful oxidizer }}<!-- | Other silver(II) [[halide]]s | no other AgX<sub>2</sub> stable<br />at room temp. |- --> | Section8 = {{Chembox Related | OtherCpds = [[Silver(I) fluoride|Silver(I) fluoride, AgF]]<br />[[Silver subfluoride|Silver subfluoride, Ag<sub>2</sub>F]]<br />[[Silver(II) oxide|Silver(II) oxide, AgO]]<br />[[Silver(I) oxide|Silver(I) oxide, Ag<sub>2</sub>O]] }} }} '''Silver(II) fluoride''' is a [[chemical compound]] with the [[chemical formula|formula]] AgF<sub>2</sub>. It is a rare example of a silver(II) compound. Silver is usually present in its +1 [[oxidation state]]. It is used as a fluorinating agent. ==Preparation== AgF<sub>2</sub> can be synthesized by fluorinating Ag<sub>2</sub>O with elemental [[fluorine]]. Also, at 200 °C (473 K) elemental fluorine will react with [[silver(I) fluoride|AgF]] or [[AgCl]] to produce AgF<sub>2</sub>.{{ref|IS}}{{ref|encyclo}} As a strong fluorinating agent, AgF<sub>2</sub> should be stored in [[Teflon]], a passivated metal container, or a [[quartz]] tube. It is light sensitive. AgF<sub>2</sub> can be purchased from various suppliers, the demand being less than 100 kg/year. While laboratory experiments find use for AgF<sub>2</sub>, it is too expensive for large scale industry use. In 1993, AgF<sub>2</sub> cost between 1000-1400 [[US dollar]]s per kg. ==Composition and structure== AgF<sub>2</sub> is a white crystalline powder, but it is usually black/brown due to impurities. The F/Ag ratio for most samples is< 2, typically approaching 1.75 due to contamination with Ag and [[oxygen|oxides]] and [[carbon]]. {{ref|XPS}} For some time, it was doubted silver was actually in the 2+ oxidation state rather in some combination of states such as Ag<sup>I</sup>[Ag<sup>III</sup>F<sub>4</sub>], which would be similar to [[silver oxide]]. [[Neutron diffraction]] studies, however, confirmed its description as silver(II). The Ag<sup>I</sup>[Ag<sup>III</sup>F<sub>4</sub>] was found to be present at high temperatures, but it was unstable with respect to AgF<sub>2</sub>.{{ref|structure}} In the gas phase, AgF<sub>2</sub> is believed to have D<sub>∞h</sub> [[symmetry group|symmetry]]. Approximately 14 [[kilocalorie|kcal]]/[[mole (unit)|mol]] (59 [[kilojoule|kJ]]/mol) separate the [[ground state|ground]] and first [[excited state|state]]s. The compound is [[paramagnetic]], but it becomes [[ferromagnetic]] at temperatures below −110 °C (163 K). ==Uses== AgF<sub>2</sub> is a strong fluorinating and oxidation agent. Illustrative applications are listed below. * Fluoronation and preparation of organic perfluorocompounds {{ref|rxns}} This type of reaction can occur in three different ways (here Z refers to any element or group attached to carbon, X is a [[halogen]]): :1) CZ<sub>3</sub>H + 2 AgF<sub>2</sub> → CZ<sub>3</sub>F +HF + 2 AgF :2) CZ<sub>3</sub>X + 2AgF<sub>2</sub> → CZ<sub>3</sub>F +X<sub>2</sub> + 2 AgF :3) Z<sub>2</sub>C=CZ<sub>2</sub> + 2 AgF<sub>2</sub> → Z<sub>2</sub>CFCFZ<sub>2</sub> + 2 AgF Similar transformations can also be effected using other high [[Valence (chemistry)|valence]] metallic fluorides such as [[cobalt(III) fluoride|CoF<sub>3</sub>]], MnF<sub>3</sub>, CeF<sub>4</sub>, and PbF<sub>4</sub>. * [[Fluorination]]s of [[aromatic]] compounds is readily achieved, but selective monofluorinations are more difficult:{{ref|monof}} :C<sub>6</sub>H<sub>6</sub> + 2 AgF<sub>2</sub> → C<sub>6</sub>H<sub>5</sub>F + 2 AgF + HF *[[Oxidation]] of [[xenon]] {{ref|Xenon}}. This reaction, which can be explosive, proceeds in [[anhydrous]] HF solutions producing XeF<sub>2</sub>. *AgF<sub>2</sub> oxidizes [[carbon monoxide]] to [[carbonyl fluoride]]. ==References== {{Citationstyle|date=September 2007}} {{reflist}} #{{note|IS}} Priest, H. F. “Anhydrous Metal Fluorides” Inorganic Syntheses McGraw-Hill: New York, 1950; Vol. 3, pages 171-183. #{{note|encyclo}} ''Encyclopedia of Chemical Technology.'' Kirk-Othermer. Vol.11, 4th Ed. ('''1991''') #{{note|XPS}} J.T. Wolan, G.B. Hoflund. "Surface Characterization Study of AgF and AgF<sub>2</sub> Powders Using XPS and ISS," ''Applied Surface Science.'' 125, ('''1998'''). #{{note|structure}} Hans-Christian Miller, Axel Schultz, and Magdolna Hargittai. "Structure and Bonding in Silver Halides: A Quantum...X=F, Cl, Br, I," [[Journal of the American Chemical Society]] 127(22), ('''2005'''). # {{note|rxns}} Rausch, D.; Davis, r.; Osborne, D. W. "The Addition of Fluorine to Halogenated Olefins by Means of Metal Fluorides," [[Journal of Organic Chemistry]] volume 28, pp. 494-497, Jul. ('''1962'''). #{{note|monof}} Zweig, A.; Fischer, R. G.; Lancaster, J. "New Methods for Selective Monofluorination of Aromatics Using Silver Difluoride," [[Journal of Organic Chemistry]] volume 45, ('''1980'''). # {{note|Xenon}} Levec, J.; Slivnik, J.; Zemva, B. "On the Reaction Between Xenon and Fluorine," ''Journal of Inorganic Nuclear Chemistry'' Volume 36, ('''1974'''). ==External links== *[http://www.npi.gov.au/database/substance-info/profiles/44.html National Pollutant Inventory Fluoride and compounds fact sheet] *[http://www.webelements.com/webelements/compounds/text/Ag/Ag1F2-7783951.html WebElements Silver(II) Fluoride] *[http://www.chem.ox.ac.uk/inorganicchemistry3/Ag/AgF2.html Structure graphic] [[Category:Fluorides]] [[Category:Silver compounds]] [[Category:Metal halides]] [[de:Silber(II)-fluorid]] [[fr:Difluorure d'argent]] [[zh:二氟化银]]