Silver(II) fluoride

AgF₂ can be synthesized by fluorinating Ag₂O with elemental fluorine. Also, at 200 °C (473 K) elemental fluorine will react with AgF or AgCl to produce AgF₂.{{cite book | author = Priest, H. F. | journal = Inorg. Synth. | year = 1950 | volume = 3 | pages = 171–183 | doi = 10.1002/9780470132340.ch47 | last2 = Swinehert | first2 = Carl F. | title = Inorganic Syntheses | chapter = Anhydrous Metal Fluorides | isbn = 978-0-470-13234-0}}Encyclopedia of Chemical Technology. Kirk-Othermer. Vol.11, 4th Ed. (1991)

As a strong fluorinating agent, AgF₂ should be stored in Teflon or a passivated metal container. It is light sensitive.

AgF₂ can be purchased from various suppliers, the demand being less than 100 kg/year. While laboratory experiments find use for AgF₂, it is too expensive for large scale industry use. In 1993, AgF₂ cost between 1000-1400 US dollars per kg.

AgF₂ 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 oxides and carbon.{{cite journal |author1=J.T. Wolan |author2=G.B. Hoflund | title = Surface Characterization Study of AgF and AgF₂ Powders Using XPS and ISS | journal = Applied Surface Science | volume = 125 | year = 1998 | doi = 10.1016/S0169-4332(97)00498-4 | pages = 251 | issue = 3–4|bibcode=1998ApSS..125..251W }}

For some time, it was doubted that silver was actually in the +2 oxidation state, rather than some combination of states such as Ag^I[Ag^IIIF₄], which would be similar to silver(I,III) oxide. Neutron diffraction studies, however, confirmed its description as silver(II). The Ag^I[Ag^IIIF₄] was found to be present at high temperatures, but it was unstable with respect to AgF₂.{{cite journal |author1=Hans-Christian Miller |author2=Axel Schultz |author3=Magdolna Hargittai |name-list-style=amp | doi = 10.1021/ja051442j | journal = J. Am. Chem. Soc. | volume = 127 | issue = 22 | year = 2005 | title = Structure and Bonding in Silver Halides. A Quantum Chemical Study of the Monomers: Ag2X, AgX, AgX2, and AgX3(X = F, Cl, Br, I) | pages = 8133–45 | pmid = 15926841}}

In the gas phase, AgF₂ is believed to have D_∞h symmetry. Crystal structure of AgF₂ was determined by single-crystal X-ray diffraction.{{Cite journal |last=Jesih |first=A. |last2=Lutar |first2=K. |last3=Žemva |first3=B. |last4=Bachmann |first4=B. |last5=Becker |first5=St. |last6=Müller |first6=B. G. |last7=Hoppe |first7=R. |date=1990-01-22 |title=Einkristalluntersuchungen an AgF 2 |url=https://onlinelibrary.wiley.com/doi/10.1002/zaac.19905880110 |journal=Zeitschrift für anorganische und allgemeine Chemie |language=en |volume=588 |issue=1 |pages=77–83 |doi=10.1002/zaac.19905880110 |issn=0044-2313}}

Approximately 14 kcal/mol (59 kJ/mol) separate the ground and first excited states. The compound is paramagnetic, but it becomes ferromagnetic at temperatures below −110 °C (163 K).

AgF₂ is a strong fluorinating and oxidising agent. It is formed as an intermediate in the catalysis of gaseous reactions with fluorine by silver. With fluoride ions, it forms complex ions such as {{chem|AgF|3|-}}, the blue-violet {{chem|AgF|4|2-}}, and {{chem|AgF|6|4-}}.{{cite book

| title = Inorganic chemistry

| author1 = Egon Wiberg

| author2 = Nils Wiberg

| author3 = Arnold Frederick Holleman

| publisher = Academic Press

| year = 2001

| isbn = 0-12-352651-5

| pages = 1272–1273

}}

It is used in the fluorination and preparation of organic perfluorocompounds.{{cite journal |author1=Rausch, D. |author2=Davis, r. |author3=Osborne, D. W. | title = The Addition of Fluorine to Halogenated Olefins by Means of Metal Fluorides | journal = J. Org. Chem. | volume = 28 | pages = 494–497 | year = 1963 | doi = 10.1021/jo01037a055 | issue = 2}} 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. CZ₃H + 2 AgF₂ → CZ₃F + HF + 2 AgF
2. CZ₃X + 2AgF₂ → CZ₃F + X₂ + 2 AgF
3. Z₂C=CZ₂ + 2 AgF₂ → Z₂CFCFZ₂ + 2 AgF

Similar transformations can also be effected using other high valence metallic fluorides such as CoF₃, MnF₃, CeF₄, and PbF₄.

{{chem|AgF|2}} is also used in the fluorination of aromatic compounds, although selective monofluorinations are more difficult:{{cite journal |author1=Zweig, A. |author2=Fischer, R. G. |author3=Lancaster, J. | title = New Methods for Selective Monofluorination of Aromatics Using Silver Difluoride | journal = J. Org. Chem. | volume = 45 | year = 1980 | doi = 10.1021/jo01306a011 | pages = 3597 | issue = 18}}

:C₆H₆ + 2 AgF₂ → C₆H₅F + 2 AgF + HF

{{chem|AgF|2}} oxidises xenon to xenon difluoride in anhydrous HF solutions.{{cite journal |author1=Levec, J. |author2=Slivnik, J. |author3=Zemva, B. | title = On the Reaction Between Xenon and Fluorine | journal = Journal of Inorganic and Nuclear Chemistry | volume = 36 | year = 1974 | doi =10.1016/0022-1902(74)80203-4 | pages = 997 | issue = 5}}

:2 AgF₂ + Xe → 2 AgF + XeF₂

It also oxidises carbon monoxide to carbonyl fluoride.

:2 AgF₂ + CO → 2 AgF + COF₂

It reacts with water to form oxygen gas:{{citation needed|date=May 2010}}

:4 AgF₂ + 4 H₂O → 2 Ag₂O + 8 HF + O₂

{{chem|AgF|2}} can be used to selectively fluorinate pyridine at the ortho position under mild conditions.{{cite journal |author1=Fier, P. S. |author2=Hartwig, J. F. | title = Selective C-H Fluorination of Pyridines and Diazines Inspired by a Classic Amination Reaction | journal = Science | volume = 342 | year = 2013 |issue=6161 | doi =10.1126/science.1243759 | pages = 956–960 | pmid=24264986|bibcode=2013Sci...342..956F |s2cid=6584890 }}

{{chem|AgF|2}} is a very strong oxidizer that reacts violently with water,{{cite book

| title = Handbook of inorganic compounds

| author1 = Dale L. Perry

| author2 = Sidney L. Phillips

| publisher = CRC Press

| year = 1995

| isbn = 0-8493-8671-3

| page = 352

}} reacts with dilute acids to produce ozone, oxidizes iodide to iodine,{{cite book

| title = Purification of Laboratory Chemicals

| publisher = Butterworth-Heinemann

| author1 = W. L. F. Armarego

| author2 = Christina Li Lin Chai

| edition = 6th

| year = 2009

| isbn = 978-1-85617-567-8

| page = 490

}} and upon contact with acetylene forms the contact explosive silver acetylide.{{cite book

| title = Wiley Guide to Chemical Incompatibilities

| author1 = Richard P. Pohanish

| author2 = Stanley A. Greene

| edition = 3rd

| publisher = John Wiley and Sons

| year = 2009

| isbn = 978-0-470-38763-4

| page = 93

}} It is light-sensitive, very hygroscopic and corrosive. It decomposes violently on contact with hydrogen peroxide, releasing oxygen gas. It also liberates HF, {{chem|F|2}}, and elemental silver.

{{Reflist}}

{{Commons category|Silver(II) fluoride}}

• [https://web.archive.org/web/20060116134617/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] {{Webarchive|url=https://web.archive.org/web/20160303165537/http://www.chem.ox.ac.uk/inorganicchemistry3/Ag/AgF2.html |date=2016-03-03 }}

{{Silver compounds}}

{{fluorides}}

{{DEFAULTSORT:Silver(Ii) Fluoride}}

Category:Fluorides

Category:Silver compounds

Category:Metal halides

Category:Fluorinating agents