Silver(II) fluoride

Last updated
Silver(II) fluoride
Silver(II)-fluoride-3D-ionic.png
Silver(II) fluoride.jpg
Names
IUPAC name
silver(II) fluoride
Other names
silver difluoride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.124 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 232-037-5
PubChem CID
UNII
  • InChI=1S/Ag.2FH/h;2*1H/q+2;;/p-2 Yes check.svgY
    Key: KWVVTSALYXIJSS-UHFFFAOYSA-L Yes check.svgY
  • 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
Appearancewhite 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:
GHS-pictogram-rondflam.svg GHS-pictogram-acid.svg GHS-pictogram-skull.svg GHS-pictogram-exclam.svg
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.svgHealth 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).
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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.

Contents

Preparation

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

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.

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

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
. [5]

It is used in the fluorination and preparation of organic perfluorocompounds. [6] 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: [7]

C6H6 + 2 AgF2 → C6H5F + 2 AgF + HF

AgF
2
oxidises xenon to xenon difluoride in anhydrous HF solutions. [8]

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. [9]

Safety

AgF
2
is a very strong oxidizer that reacts violently with water, [10] reacts with dilute acids to produce ozone, oxidizes iodide to iodine, [10] [11] and upon contact with acetylene forms the contact explosive silver acetylide. [12] It is light-sensitive, [10] very hygroscopic and corrosive. It decomposes violently on contact with hydrogen peroxide, releasing oxygen gas. [12] It also liberates HF, F
2
, and elemental silver. [11]

Related Research Articles

In chemistry, an interhalogen compound is a molecule which contains two or more different halogen atoms and no atoms of elements from any other group.

<span class="mw-page-title-main">Oxygen difluoride</span> Chemical compound

Oxygen difluoride is a chemical compound with the formula OF2. As predicted by VSEPR theory, the molecule adopts a bent molecular geometry. It is a strong oxidizer and has attracted attention in rocketry for this reason. With a boiling point of −144.75 °C, OF2 is the most volatile (isolable) triatomic compound. The compound is one of many known oxygen fluorides.

<span class="mw-page-title-main">Oxygen fluoride</span> Any binary compound of oxygen and fluorine

Oxygen fluorides are compounds of elements oxygen and fluorine with the general formula OnF2, where n = 1 to 6. Many different oxygen fluorides are known:

<span class="mw-page-title-main">Nickel(II) fluoride</span> Chemical compound

Nickel(II) fluoride is the chemical compound with the formula NiF2. It is an ionic compound of nickel and fluorine and forms yellowish to green tetragonal crystals. Unlike many fluorides, NiF2 is stable in air.

<span class="mw-page-title-main">Platinum hexafluoride</span> Chemical compound

Platinum hexafluoride is the chemical compound with the formula PtF6, and is one of seventeen known binary hexafluorides. It is a dark-red volatile solid that forms a red gas. The compound is a unique example of platinum in the +6 oxidation state. With only four d-electrons, it is paramagnetic with a triplet ground state. PtF6 is a strong fluorinating agent and one of the strongest oxidants, capable of oxidising xenon and O2. PtF6 is octahedral in both the solid state and in the gaseous state. The Pt-F bond lengths are 185 picometers.

<span class="mw-page-title-main">Tellurium tetrafluoride</span> Chemical compound

Tellurium tetrafluoride, TeF4, is a stable, white, hygroscopic crystalline solid and is one of two fluorides of tellurium. The other binary fluoride is tellurium hexafluoride. The widely reported Te2F10 has been shown to be F5TeOTeF5 There are other tellurium compounds that contain fluorine, but only the two mentioned contain solely tellurium and fluorine. Tellurium difluoride, TeF2, and ditellurium difluoride, Te2F2 are not known.

<span class="mw-page-title-main">Xenon difluoride</span> Chemical compound

Xenon difluoride is a powerful fluorinating agent with the chemical formula XeF
2
, and one of the most stable xenon compounds. Like most covalent inorganic fluorides it is moisture-sensitive. It decomposes on contact with water vapor, but is otherwise stable in storage. Xenon difluoride is a dense, colourless crystalline solid.

<span class="mw-page-title-main">Selenium tetrafluoride</span> Chemical compound

Selenium tetrafluoride (SeF4) is an inorganic compound. It is a colourless liquid that reacts readily with water. It can be used as a fluorinating reagent in organic syntheses (fluorination of alcohols, carboxylic acids or carbonyl compounds) and has advantages over sulfur tetrafluoride in that milder conditions can be employed and it is a liquid rather than a gas.

<span class="mw-page-title-main">Xenon oxytetrafluoride</span> Chemical compound

Xenon oxytetrafluoride is an inorganic chemical compound. It is an unstable colorless liquid with a melting point of −46.2 °C that can be synthesized by partial hydrolysis of XeF
6
, or the reaction of XeF
6
with silica or NaNO
3
:

<span class="mw-page-title-main">Krypton difluoride</span> Chemical compound

Krypton difluoride, KrF2 is a chemical compound of krypton and fluorine. It was the first compound of krypton discovered. It is a volatile, colourless solid at room temperature. The structure of the KrF2 molecule is linear, with Kr−F distances of 188.9 pm. It reacts with strong Lewis acids to form salts of the KrF+ and Kr
2
F+
3
cations.

<span class="mw-page-title-main">Dioxygenyl</span> Chemical compound

The dioxygenyl ion, O+
2
, is a rarely-encountered oxycation in which both oxygen atoms have a formal oxidation state of +1/2. It is formally derived from oxygen by the removal of an electron:

<span class="mw-page-title-main">Manganese(IV) fluoride</span> Chemical compound

Manganese tetrafluoride, MnF4, is the highest fluoride of manganese. It is a powerful oxidizing agent and is used as a means of purifying elemental fluorine.

A hexafluoride is a chemical compound with the general formula QXnF6, QXnF6m−, or QXnF6m+. Many molecules fit this formula. An important hexafluoride is hexafluorosilicic acid (H2SiF6), which is a byproduct of the mining of phosphate rock. In the nuclear industry, uranium hexafluoride (UF6) is an important intermediate in the purification of this element.

<span class="mw-page-title-main">Chromyl fluoride</span> Chemical compound

Chromyl fluoride is an inorganic compound with the formula CrO2F2. It is a violet-red colored crystalline solid that melts to an orange-red liquid.

<span class="mw-page-title-main">Neptunium(VI) fluoride</span> Chemical compound

Neptunium(VI) fluoride (NpF6) is the highest fluoride of neptunium, it is also one of seventeen known binary hexafluorides. It is an orange volatile crystalline solid. It is relatively hard to handle, being very corrosive, volatile and radioactive. Neptunium hexafluoride is stable in dry air but reacts vigorously with water.

Fluorine forms a great variety of chemical compounds, within which it always adopts an oxidation state of −1. With other atoms, fluorine forms either polar covalent bonds or ionic bonds. Most frequently, covalent bonds involving fluorine atoms are single bonds, although at least two examples of a higher order bond exist. Fluoride may act as a bridging ligand between two metals in some complex molecules. Molecules containing fluorine may also exhibit hydrogen bonding. Fluorine's chemistry includes inorganic compounds formed with hydrogen, metals, nonmetals, and even noble gases; as well as a diverse set of organic compounds. For many elements the highest known oxidation state can be achieved in a fluoride. For some elements this is achieved exclusively in a fluoride, for others exclusively in an oxide; and for still others the highest oxidation states of oxides and fluorides are always equal.

Radical fluorination is a type of fluorination reaction, complementary to nucleophilic and electrophilic approaches. It involves the reaction of an independently generated carbon-centered radical with an atomic fluorine source and yields an organofluorine compound.

Thullium(III) fluoride is an inorganic compound with the chemical formula TmF3.

<span class="mw-page-title-main">Terbium(IV) fluoride</span> Chemical compound

Terbium(IV) fluoride is an inorganic compound with a chemical formula TbF4. It is a white solid that is a strong oxidizer. It is also a strong fluorinating agent, emitting relatively pure atomic fluorine when heated, rather than the mixture of fluoride vapors emitted from cobalt(III) fluoride or cerium(IV) fluoride. It can be produced by the reaction between very pure terbium(III) fluoride and xenon difluoride, chlorine trifluoride or fluorine gas:

<span class="mw-page-title-main">Seleninyl fluoride</span> Chemical compound

Seleninyl fluoride is an oxyfluoride of selenium with the chemical formula SeOF2.

References

  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. Egon Wiberg; Nils Wiberg; Arnold Frederick Holleman (2001). Inorganic chemistry. Academic Press. pp. 1272–1273. ISBN   0-12-352651-5.
  6. 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.
  7. 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.
  8. 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.
  9. 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.
  10. 1 2 3 Dale L. Perry; Sidney L. Phillips (1995). Handbook of inorganic compounds. CRC Press. p. 352. ISBN   0-8493-8671-3.
  11. 1 2 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.
  12. 1 2 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.