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{{chembox
{{chembox
| Verifiedfields = changed
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| verifiedrevid = 401054886
| Watchedfields = changed
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| Name = Silver(II) fluoride
⚫
| verifiedrevid = 464391669
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| ImageFile = Silver(II)-fluoride-3D-ionic.png
⚫
| Name = Silver(II) fluoride
<!-- | ImageSize = 200px -->
| ImageName = Silver(II) fluoride
| ImageFile = Silver(II)-fluoride-3D-ionic.png
| IUPACName = silver(II) fluoride
| ImageName = Silver(II) fluoride
⚫
| ImageFile2 = Silver(II) fluoride.jpg
⚫
| OtherNames = silver difluoride
| IUPACName = silver(II) fluoride
⚫
| Section1 = {{Chembox Identifiers
⚫
| OtherNames = silver difluoride
⚫
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
⚫
|Section1={{Chembox Identifiers
⚫
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 10802085
| ChemSpiderID = 10802085
| InChI = 1/Ag.2FH/h;2*1H/q+2;;/p-2
| InChI = 1/Ag.2FH/h;2*1H/q+2;;/p-2
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = KWVVTSALYXIJSS-UHFFFAOYSA-L
| StdInChIKey = KWVVTSALYXIJSS-UHFFFAOYSA-L
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 7783-95-1
| CASNo = 7783-95-1
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 372MAR8LH9
| PubChem = 82221
| EINECS = 232-037-5
}}
}}
| Section2 = {{Chembox Properties
|Section2={{Chembox Properties
| Formula = AgF<sub>2</sub>
| Formula = AgF<sub>2</sub>
| MolarMass = 145.865 g/mol
| MolarMass = 145.865 g/mol
| Appearance = white or grey crystalline powder, [[hygroscopic]]
| Appearance = white or grey crystalline powder, [[hygroscopic]]
| Density = 4.58 g/cm<sup>3</sup>
| Density = 4.58 g/cm<sup>3</sup>
| Solubility = Decomposes, violently
| Solubility = Decomposes
| MeltingPt = 690 °C (963 K)
| MeltingPtC = 690
| BoilingPtC = 700
| BoilingPt = decomposes at 700 °C (973 K)
| BoilingPt_notes = (decomposes)
}}
}}
| Section3 = {{Chembox Structure
|Section3={{Chembox Structure
| MolShape = linear
| MolShape = linear
| Coordination = tetragonally elongated<br />octahedral coordination
| Coordination = tetragonally elongated<br />octahedral coordination
| CrystalStruct = orthorhombic
| CrystalStruct = orthorhombic
}}
}}
| Section7 = {{Chembox Hazards
|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]
| ExternalSDS = [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
| MainHazards = toxic, reacts violently with water, powerful oxidizer
| NFPA-F = 0
| NFPA-H = 3
| NFPA-R = 3
| NFPA-S = W+OX
| GHSPictograms = {{GHS03}}{{GHS05}}{{GHS06}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|272|301|302|311|312|314|331|332}}
| PPhrases = {{P-phrases|210|220|221|260|261|264|270|271|280|301+310|301+312|301+330+331|302+352|303+361+353|304+312|304+340|305+351+338|310|311|312|321|322|330|361|363|370+378|403+233|405|501}}
}}
}}
| Section8 = {{Chembox Related
|Section8={{Chembox Related
| OtherAnions = [[silver(I,III) oxide]] <!-- no other AgX2 stable at room temp. -->
| OtherAnions = [[Silver(I,III) oxide]] <!-- no other AgX2 stable at room temp. -->
| OtherCations = [[copper(II) fluoride]], [[palladium(II) fluoride]], [[cadmium(II) fluoride]]
| OtherCations = [[Copper(II) fluoride]]<br />[[Palladium(II) fluoride]]<br />[[Zinc fluoride]]<br />[[Cadmium(II) fluoride]]<br />[[Mercury(II) fluoride]]
| OtherCpds = [[silver(I) fluoride]]
| OtherCompounds = [[Silver subfluoride]]<br />[[Silver(I) fluoride]]
}}
}}
}}
}}


'''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.
'''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]] usually exists in its +1 [[oxidation state]]. It is used as a fluorinating agent.


==Preparation==
==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>{{cite journal | author = Priest, H. F. | title = Anhydrous Metal Fluorides | journal = [[Inorg. Synth.]] | year = 1950 | volume = 3 | pages = 171–183 | doi = 10.1002/9780470132340.ch47 | last2 = Swinehert | first2 = Carl F.}}</ref><ref>''Encyclopedia of Chemical Technology.'' Kirk-Othermer. Vol.11, 4th Ed. ('''1991''')</ref>
AgF<sub>2</sub> can be synthesized by fluorinating Ag<sub>2</sub>O with elemental [[fluorine]]. Also, at 200&nbsp;°C (473 K) elemental fluorine will react with [[silver(I) fluoride|AgF]] or [[AgCl]] to produce AgF<sub>2</sub>.<ref>{{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}}</ref><ref>''Encyclopedia of Chemical Technology.'' Kirk-Othermer. Vol.11, 4th Ed. ('''1991''')</ref>


As a strong fluorinating agent, AgF<sub>2</sub> should be stored in [[Teflon]] or a passivated metal container. It is light sensitive.
As a strong fluorinating agent, AgF<sub>2</sub> should be stored in [[Teflon]] or a passivated metal container. It is light sensitive.
Line 54: Line 70:


==Composition and structure==
==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 [[silver|Ag]] and [[oxygen|oxides]] and [[carbon]].<ref>{{cite journal | author = J.T. Wolan, G.B. Hoflund | title = Surface Characterization Study of AgF and AgF<sub>2</sub> Powders Using XPS and ISS | journal = Applied Surface Science | volume = 125 | year = 1998 | doi = 10.1016/S0169-4332(97)00498-4 | pages = 251}}</ref>
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 [[silver|Ag]] and [[oxygen|oxides]] and [[carbon]].<ref>{{cite journal |author1=J.T. Wolan |author2=G.B. Hoflund | title = Surface Characterization Study of AgF and AgF<sub>2</sub> 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 }}</ref>


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>{{cite journal | author = Hans-Christian Miller, Axel Schultz, and Magdolna Hargittai | 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 | pmid = 15926841}}</ref>
For some time, it was doubted that silver was actually in the +2 oxidation state, rather than some combination of states such as Ag<sup>I</sup>[Ag<sup>III</sup>F<sub>4</sub>], which would be similar to [[silver(I,III) 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>{{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}}</ref>


In the gas phase, AgF<sub>2</sub> is believed to have D<sub>∞h</sub> [[symmetry group|symmetry]]. Crystal structure of AgF<sub>2</sub> was determined by [[X-ray crystallography|single-crystal X-ray diffraction]].<ref>{{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}}</ref>
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).
Approximately 14 [[kilocalorie|kcal]]/[[mole (unit)|mol]] (59 [[kilojoule|kJ]]/mol) separate the [[ground state|ground]] and [[Excited state|first excited states]]. The compound is [[paramagnetic]], but it becomes [[ferromagnetic]] at temperatures below −110&nbsp;°C (163 K).


==Uses==
==Uses==
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| publisher = Academic Press
| publisher = Academic Press
| year = 2001
| year = 2001
| isbn = 0123526515
| isbn = 0-12-352651-5
| pages = 1272–1273
| pages = 1272–1273
}}</ref>
}}</ref>


It is used in the fluorination and preparation of organic perfluorocompounds.<ref>{{cite journal | author = Rausch, D.; Davis, r.; 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 = 1962 | doi = 10.1021/jo01037a055}}</ref> 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]]):
It is used in the fluorination and preparation of organic perfluorocompounds.<ref>{{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}}</ref> 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]]):
# CZ<sub>3</sub>H + 2 AgF<sub>2</sub> → CZ<sub>3</sub>F +HF + 2 AgF
# CZ<sub>3</sub>H + 2 AgF<sub>2</sub> → CZ<sub>3</sub>F + HF + 2 AgF
# CZ<sub>3</sub>X + 2AgF<sub>2</sub> → CZ<sub>3</sub>F +X<sub>2</sub> + 2 AgF
# CZ<sub>3</sub>X + 2AgF<sub>2</sub> → CZ<sub>3</sub>F + X<sub>2</sub> + 2 AgF
# Z<sub>2</sub>C=CZ<sub>2</sub> + 2 AgF<sub>2</sub> → Z<sub>2</sub>CFCFZ<sub>2</sub> + 2 AgF
# 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>.
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>.


{{chem|AgF|2}} is also used in the fluorination of [[aromatic]] compounds, although selective monofluorinations are more difficult:<ref>{{cite journal | author = Zweig, A.; Fischer, R. G.; 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}}</ref>
{{chem|AgF|2}} is also used in the fluorination of [[aromatic]] compounds, although selective monofluorinations are more difficult:<ref>{{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}}</ref>


: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
: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


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


:2 AgF<sub>2</sub> + Xe → 2 AgF + XeF<sub>2</sub>
:2 AgF<sub>2</sub> + Xe → 2 AgF + XeF<sub>2</sub>
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:4 AgF<sub>2</sub> + 4 H<sub>2</sub>O → 2 Ag<sub>2</sub>O + 8 HF + O<sub>2</sub>
:4 AgF<sub>2</sub> + 4 H<sub>2</sub>O → 2 Ag<sub>2</sub>O + 8 HF + O<sub>2</sub>


{{chem|AgF|2}} can be used to selectively fluorinate [[pyridine]] at the ortho position under mild conditions.<ref>{{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 }}</ref>
⚫
==Safety==


⚫
==Safety==
{{chem|AgF|2}} is a very strong oxidizer that reacts violently with water,<ref name="perry">{{cite book
{{chem|AgF|2}} is a very strong oxidizer that reacts violently with water,<ref name="perry">{{cite book
| title = Handbook of inorganic compounds
| title = Handbook of inorganic compounds
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| publisher = CRC Press
| publisher = CRC Press
| year = 1995
| year = 1995
| isbn = 0849386713
| isbn = 0-8493-8671-3
| page = 352
| page = 352
}}</ref> reacts with dilute acids to produce [[ozone]], oxidizes [[iodide]] to [[iodine]],<ref name="perry"/><ref name="armarego">{{cite book
}}</ref> reacts with dilute acids to produce [[ozone]], oxidizes [[iodide]] to [[iodine]],<ref name="perry" /><ref name="armarego">{{cite book
| title = Purification of Laboratory Chemicals
| title = Purification of Laboratory Chemicals
| publisher = Butterworth-Heinemann
| publisher = Butterworth-Heinemann
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| edition = 6th
| edition = 6th
| year = 2009
| year = 2009
| isbn = 1856175677
| isbn = 978-1-85617-567-8
| page = 490
| page = 490
}}</ref> and upon contact with [[acetylene]] forms the contact explosive [[silver acetylide]].<ref name="pohanish">{{cite book
}}</ref> and upon contact with [[acetylene]] forms the contact explosive [[silver acetylide]].<ref name="pohanish">{{cite book
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| publisher = John Wiley and Sons
| publisher = John Wiley and Sons
| year = 2009
| year = 2009
| isbn = 0470387637
| isbn = 978-0-470-38763-4
| page = 93
| page = 93
}}</ref> It is light-sensitive,<ref name="perry"/> very [[hygroscopic]] and corrosive. It decomposes violently on contact with [[hydrogen peroxide]], releasing oxygen gas.<ref name="pohanish"/> It also liberates [[hydrogen fluoride|HF]] and {{chem|F|2}}.<ref name="armarego"/>
}}</ref> It is light-sensitive,<ref name="perry" /> very [[hygroscopic]] and corrosive. It decomposes violently on contact with [[hydrogen peroxide]], releasing oxygen gas.<ref name="pohanish" /> It also liberates [[hydrogen fluoride|HF]], {{chem|F|2}}, and elemental silver.<ref name="armarego" />


==References==
== References ==
{{reflist}}
{{Reflist}}


==External links==
==External links==
⚫
{{Commons category|Silver(II) fluoride}}
*[http://www.npi.gov.au/database/substance-info/profiles/44.html National Pollutant Inventory Fluoride and compounds fact sheet]
* [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]
* [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}}
{{Silver compounds}}
{{fluorides}}


{{DEFAULTSORT:Silver(Ii) Fluoride}}
{{DEFAULTSORT:Silver(Ii) Fluoride}}
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[[Category:Metal halides]]
[[Category:Metal halides]]
[[Category:Fluorinating agents]]
[[Category:Fluorinating agents]]

[[de:Silber(II)-fluorid]]
[[fr:Difluorure d'argent]]
[[nl:Zilver(II)fluoride]]
⚫
[[simple:Silver(II) fluoride]]
[[tl:Silver(II) fluoride]]
[[zh:二氟化银]]

Latest revision as of 21:52, 23 December 2024

Silver(II) fluoride
Silver(II) fluoride
Names
IUPAC name
silver(II) fluoride
Other names
silver difluoride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.124 Edit this at Wikidata
EC Number
  • 232-037-5
UNII
  • InChI=1S/Ag.2FH/h;2*1H/q+2;;/p-2 checkY
    Key: KWVVTSALYXIJSS-UHFFFAOYSA-L checkY
  • InChI=1/Ag.2FH/h;2*1H/q+2;;/p-2
    Key: KWVVTSALYXIJSS-NUQVWONBAP
  • [Ag+2].[F-].[F-]
Properties
AgF2
Molar mass 145.865 g/mol
Appearance white or grey crystalline powder, hygroscopic
Density 4.58 g/cm3
Melting point 690 °C (1,274 °F; 963 K)
Boiling point 700 °C (1,292 °F; 973 K) (decomposes)
Decomposes
Structure
orthorhombic
tetragonally elongated
octahedral coordination
linear
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 toxic, reacts violently with water, powerful oxidizer
GHS labelling:
GHS03: OxidizingGHS05: CorrosiveGHS06: Toxic
Danger
H272, H301, H302, H311, H312, H314, H331, H332
P210, P220, P221, P260, P261, P264, P270, P271, P280, P301+P310, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P310, P311, P312, P321, P322, P330, P361, P363, P370+P378, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazard W+OX: Reacts with water in an unusual or dangerous manner AND is oxidizer
3
0
3
W
OX
Safety data sheet (SDS) MSDS
Related compounds
Other anions
 Silver(I,III) oxide
Other cations
 Copper(II) fluoride
Palladium(II) fluoride
Zinc fluoride
Cadmium(II) fluoride
Mercury(II) fluoride
Related compounds
 Silver subfluoride
Silver(I) fluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Silver(II) fluoride is a chemical compound with the formula AgF2. It is a rare example of a silver(II) compound - silver usually exists in its +1 oxidation state. It is used as a fluorinating agent.

Preparation

[edit]

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.[1][2]

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.

Composition and structure

[edit]

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.[3]

For some time, it was doubted that silver was actually in the +2 oxidation state, rather than some combination of states such as AgI[AgIIIF4], which would be similar to silver(I,III) oxide. Neutron diffraction studies, however, confirmed its description as silver(II). The AgI[AgIIIF4] was found to be present at high temperatures, but it was unstable with respect to AgF2.[4]

In the gas phase, AgF2 is believed to have D∞h symmetry. Crystal structure of AgF2 was determined by single-crystal X-ray diffraction.[5]

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).

Uses

[edit]

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 AgF−
3, the blue-violet AgF2−
4, and AgF4−
6.[6]

It is used in the fluorination and preparation of organic perfluorocompounds.[7] 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.

AgF
2 is also used in the fluorination of aromatic compounds, although selective monofluorinations are more difficult:[8]

C6H6 + 2 AgF2 → C6H5F + 2 AgF + HF

AgF
2 oxidises xenon to xenon difluoride in anhydrous HF solutions.[9]

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]

4 AgF2 + 4 H2O → 2 Ag2O + 8 HF + O2

AgF
2 can be used to selectively fluorinate pyridine at the ortho position under mild conditions.[10]

Safety

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AgF
2 is a very strong oxidizer that reacts violently with water,[11] reacts with dilute acids to produce ozone, oxidizes iodide to iodine,[11][12] and upon contact with acetylene forms the contact explosive silver acetylide.[13] It is light-sensitive,[11] very hygroscopic and corrosive. It decomposes violently on contact with hydrogen peroxide, releasing oxygen gas.[13] It also liberates HF, F
2, and elemental silver.[12]

References

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  1. ^ Priest, H. F.; Swinehert, Carl F. (1950). "Anhydrous Metal Fluorides". Inorganic Syntheses. Vol. 3. pp. 171–183. doi:10.1002/9780470132340.ch47. ISBN 978-0-470-13234-0. {{cite book}}: |journal= ignored (help)
  2. ^ Encyclopedia of Chemical Technology. Kirk-Othermer. Vol.11, 4th Ed. (1991)
  3. ^ J.T. Wolan; G.B. Hoflund (1998). "Surface Characterization Study of AgF and AgF2 Powders Using XPS and ISS". Applied Surface Science. 125 (3–4): 251. Bibcode:1998ApSS..125..251W. doi:10.1016/S0169-4332(97)00498-4.
  4. ^ Hans-Christian Miller; Axel Schultz & Magdolna Hargittai (2005). "Structure and Bonding in Silver Halides. A Quantum Chemical Study of the Monomers: Ag2X, AgX, AgX2, and AgX3(X = F, Cl, Br, I)". J. Am. Chem. Soc. 127 (22): 8133–45. doi:10.1021/ja051442j. PMID 15926841.
  5. ^ Jesih, A.; Lutar, K.; Žemva, B.; Bachmann, B.; Becker, St.; Müller, B. G.; Hoppe, R. (1990-01-22). "Einkristalluntersuchungen an AgF 2". Zeitschrift für anorganische und allgemeine Chemie. 588 (1): 77–83. doi:10.1002/zaac.19905880110. ISSN 0044-2313.
  6. ^ Egon Wiberg; Nils Wiberg; Arnold Frederick Holleman (2001). Inorganic chemistry. Academic Press. pp. 1272–1273. ISBN 0-12-352651-5.
  7. ^ Rausch, D.; Davis, r.; Osborne, D. W. (1963). "The Addition of Fluorine to Halogenated Olefins by Means of Metal Fluorides". J. Org. Chem. 28 (2): 494–497. doi:10.1021/jo01037a055.
  8. ^ Zweig, A.; Fischer, R. G.; Lancaster, J. (1980). "New Methods for Selective Monofluorination of Aromatics Using Silver Difluoride". J. Org. Chem. 45 (18): 3597. doi:10.1021/jo01306a011.
  9. ^ Levec, J.; Slivnik, J.; Zemva, B. (1974). "On the Reaction Between Xenon and Fluorine". Journal of Inorganic and Nuclear Chemistry. 36 (5): 997. doi:10.1016/0022-1902(74)80203-4.
  10. ^ Fier, P. S.; Hartwig, J. F. (2013). "Selective C-H Fluorination of Pyridines and Diazines Inspired by a Classic Amination Reaction". Science. 342 (6161): 956–960. Bibcode:2013Sci...342..956F. doi:10.1126/science.1243759. PMID 24264986. S2CID 6584890.
  11. ^ a b c Dale L. Perry; Sidney L. Phillips (1995). Handbook of inorganic compounds. CRC Press. p. 352. ISBN 0-8493-8671-3.
  12. ^ a b W. L. F. Armarego; Christina Li Lin Chai (2009). Purification of Laboratory Chemicals (6th ed.). Butterworth-Heinemann. p. 490. ISBN 978-1-85617-567-8.
  13. ^ a b Richard P. Pohanish; Stanley A. Greene (2009). Wiley Guide to Chemical Incompatibilities (3rd ed.). John Wiley and Sons. p. 93. ISBN 978-0-470-38763-4.
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