Silver(I) fluoride

Last updated
Silver(I) fluoride
Silver(I)-fluoride-3D-ionic.png
Silver(I) fluoride.jpg
Names
IUPAC name
Silver(I) fluoride
Other names
Argentous fluoride
Silver monofluoride
Identifiers
3D model (JSmol)
ECHA InfoCard 100.028.996 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
RTECS number
  • VW4250000
UNII
  • [Ag+].[F-]
Properties
AgF
Molar mass 126.8666 g·mol−1
Appearanceyellow-brown solid
Density 5.852 g/cm3 (15 °C)
Melting point 435 °C (815 °F; 708 K)
Boiling point 1,159 °C (2,118 °F; 1,432 K)
85.78 g/100 mL (0 °C)
119.8 g/100 mL (10 °C)
179.1 g/100 mL (25 °C)
213.4 g/100 mL (50 °C) [1]
Solubility 83g/100 g (11.9 °C) in hydrogen fluoride
1.5g/100 mL in methanol(25 °C) [2]
−36.5·10−6 cm3/mol
Structure
cubic
Thermochemistry
48.1 J/mol·K [1]
Std molar
entropy (S⦵298)
83.7 J/mol·K [1]
-206 kJ/mol [1]
-187.9 kJ/mol [1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Corrosive
GHS labelling: [3]
GHS-pictogram-acid.svg
Danger
H314
P260, P280, P303+P361+P353, P304+P340, P305+P351+P338, P310 [4]
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 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
0
0
Safety data sheet (SDS) External SDS
Related compounds
Other anions
Silver(I) oxide
Silver(I) chloride

Silver(I) bromide
Silver(I) iodide

Other cations
Copper(I) fluoride
Gold(I) fluoride
Related compounds
 Silver subfluoride
Silver(II) 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(I) fluoride is the inorganic compound with the formula AgF. It is one of the three main fluorides of silver, the others being silver subfluoride and silver(II) fluoride. AgF has relatively few niche applications; it has been employed as a fluorination and desilylation reagent in organic synthesis and in aqueous solution as a topical caries treatment in dentistry.

Contents

The hydrates of AgF present as colourless, while pure anhydrous samples are yellow. [5] : 150 

Preparation

High-purity silver(I) fluoride can be produced by the heating of silver carbonate to 310 °C (590 °F) under a hydrogen fluoride environment, in a platinum tube: [6] : 9 

Laboratory routes to the compound typically avoid the use of gaseous hydrogen fluoride. One method is the thermal decomposition of silver tetrafluoroborate:

In an alternative route, silver(I) oxide is dissolved in concentrated aqueous hydrofluoric acid, and the silver fluoride is precipitated out of the resulting solution by acetone. [6] : 10 

Properties

Structure

The structure of AgF has been determined by X-ray diffraction. [7] [8] : 3736  [9] At ambient temperature and pressure, silver(I) fluoride exists as the polymorph AgF-I, which adopts a cubic crystal system with space group Fm3m in the Hermann–Mauguin notation. The rock salt structure is adopted by the other silver monohalides. The lattice parameter is 4.936(1) Å, significantly lower than those of AgCl and AgBr. [10] : 562  Neutron and X-ray diffraction studies have further shown that at 2.70(2) GPa, a structural transition occurs to a second polymorph (AgF-II) with the caesium chloride structure, and lattice parameter 2.945 Å. [11] : 7945  [12] : 770  The associated decrease in volume is approximately ten percent. [11] : 7946  A third polymorph, AgF-III, forms on reducing the pressure to 2.59(2) GPa, and has an inverse nickel arsenide structure. The lattice parameters are a = 3.244(2) Å and c = 6.24(1) Å; the rock salt structure is regained only on reduction of the pressure to 0.9(1) GPa. Non-stochiometric behaviour is exhibited by all three polymorphs under extreme pressures. [13] : 939  [11] : 7947 

Spectroscopy

Silver(I) fluoride exhibits unusual optical properties. Simple electronic band theory predicts that the fundamental exciton absorption for AgF would lie higher than that of AgCl (5.10 eV) and would correspond to a transition from an anionic valence band as for the other silver halides. Experimentally, the fundamental exciton for AgF lies at 4.63 eV. [14] : 2604  This discrepancy can be explained by positing transition from a valence band with largely silver 4d-orbital character. [10] : 563  The high frequency refractive index is 1.73(2). [8] : 3737 

Photosensitivity

In contrast with the other silver halides, anhydrous silver(I) fluoride is not appreciably photosensitive, although the dihydrate is. [15] : 286  [5] : 150  With this and the material's solubility in water considered, it is unsurprising that it has found little application in photography but may have been one of the salts used by Levi Hill in his "heliochromy", [16] although a US patent for an experimental AgF-based method was granted in 1970. [17]

Solubility

Unlike the other silver halides, AgF is highly soluble in water (1800 g/L), and it even has some solubility in acetonitrile. It is also unique among silver(I) compounds and the silver halides in that it forms the hydrates AgF·(H2O)2 and AgF·(H2O)4 on precipitation from aqueous solution. [18] : 1185  [19] Like the alkali metal fluorides, it dissolves in hydrogen fluoride to give a conducting solution. [20]

Applications

Organic synthesis

Silver(I) fluoride finds application in organofluorine chemistry for addition of fluoride across multiple bonds. For example, AgF adds to perfluoroalkenes in acetonitrile to give perfluoroalkylsilver(I) derivatives. [21] : 7367  It can also be used as a desulfuration-fluorination reagent on thiourea derived substrates. [19] : 562  Due to its high solubility in water and organic solvents, it is a convenient source of fluoride ions, and can be used to fluorinate alkyl halides under mild conditions. [2] An example is given by the following reaction: [22]

Miiller1978cycpropAgF1.svg

Another organic synthetic method using silver(I) fluoride is the BINAP-AgF complex catalyzed enantioselective protonation of silyl enol ethers: [23] : 1546 

AgFBINAP.svg

Inorganic synthesis

The reaction of silver acetylide with a concentrated solution of silver(I) fluoride results in the formation of a chandelier-like [Ag10]2+ cluster with endohedral acetylenediide. [24]

Tetralkylammonium fluorides can be conveniently prepared in the laboratory by the reaction of the tetralkylammonium bromide with an aqueous AgF solution. [25] : 430 

Other

It is possible to coat a silicon surface with a uniform silver microlayer (0.1 to 1 μm thickness) by passing AgF vapour over it at 60–800 °C. [26] The relevant reaction is:

Multiple studies have shown silver(I) fluoride to be an effective anti-caries agent, although the mechanism is the subject of current research. [27] Treatment is typically by the "atraumatic" method, in which 40% by mass aqueous silver(I) fluoride solution is applied to carious leisons, followed by sealing of the dentine with glass ionomer cement. [28] Although the treatment is generally recognised to be safe, fluoride toxicity has been a significant clinical concern in paediatric applications, especially as some commercial preparations have had considerable silver(II) fluoride contamination in the past. [28] [29] [30] Due to the instability of concentrated AgF solutions, silver diamine fluoride (Ag(NH3)2F) is now more commonly used. [30] : 26  Preparation is by the addition of ammonia to aqueous silver fluoride solution or by the dissolution of silver fluoride in aqueous ammonia. [31]

Related Research Articles

<span class="mw-page-title-main">Hydrofluoric acid</span> Solution of hydrogen fluoride in water

Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colorless, acidic and highly corrosive. It is used to make most fluorine-containing compounds; examples include the commonly used pharmaceutical antidepressant medication fluoxetine (Prozac) and the material PTFE (Teflon). Elemental fluorine is produced from it. It is commonly used to etch glass and silicon wafers.

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

Zinc chloride is the name of inorganic chemical compounds with the formula ZnCl2. It forms hydrates. Zinc chloride, anhydrous and its hydrates are colorless or white crystalline solids, and are highly soluble in water. Five hydrates of zinc chloride are known, as well as four forms of anhydrous zinc chloride. This salt is hygroscopic and even deliquescent. Zinc chloride finds wide application in textile processing, metallurgical fluxes, and chemical synthesis. No mineral with this chemical composition is known aside from the very rare mineral simonkolleite, Zn5(OH)8Cl2·H2O.

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

Caesium fluoride or cesium fluoride is an inorganic compound with the formula CsF and it is a hygroscopic white salt. Caesium fluoride can be used in organic synthesis as a source of the fluoride anion. Caesium also has the highest electropositivity of all known elements and fluorine has the highest electronegativity of all known elements.

<span class="mw-page-title-main">Copper(I) chloride</span> Chemical compound

Copper(I) chloride, commonly called cuprous chloride, is the lower chloride of copper, with the formula CuCl. The substance is a white solid sparingly soluble in water, but very soluble in concentrated hydrochloric acid. Impure samples appear green due to the presence of copper(II) chloride (CuCl2).

<span class="mw-page-title-main">Potassium fluoride</span> Ionic compound (KF)

Potassium fluoride is the chemical compound with the formula KF. After hydrogen fluoride, KF is the primary source of the fluoride ion for applications in manufacturing and in chemistry. It is an alkali halide salt and occurs naturally as the rare mineral carobbiite. Solutions of KF will etch glass due to the formation of soluble fluorosilicates, although HF is more effective.

<span class="mw-page-title-main">Metal ammine complex</span>

In coordination chemistry, metal ammine complexes are metal complexes containing at least one ammonia ligand. "Ammine" is spelled this way due to historical reasons; in contrast, alkyl or aryl bearing ligands are spelt with a single "m". Almost all metal ions bind ammonia as a ligand, but the most prevalent examples of ammine complexes are for Cr(III), Co(III), Ni(II), Cu(II) as well as several platinum group metals.

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

Silver oxide is the chemical compound with the formula Ag2O. It is a fine black or dark brown powder that is used to prepare other silver compounds.

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

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.

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

Iron(III) fluoride, also known as ferric fluoride, are inorganic compounds with the formula FeF3(H2O)x where x = 0 or 3. They are mainly of interest by researchers, unlike the related iron(III) chloride. Anhydrous iron(III) fluoride is white, whereas the hydrated forms are light pink.

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

Hydrogen fluoride (fluorane) is an inorganic compound with chemical formula HF. It is a very poisonous, colorless gas or liquid that dissolves in water to yield an aqueous solution termed hydrofluoric acid. It is the principal industrial source of fluorine, often in the form of hydrofluoric acid, and is an important feedstock in the preparation of many important compounds including pharmaceuticals and polymers, e.g. polytetrafluoroethylene (PTFE). HF is also widely used in the petrochemical industry as a component of superacids. Due to strong and extensive hydrogen bonding, it boils at near room temperature, much higher than other hydrogen halides.

<span class="mw-page-title-main">Hexafluorosilicic acid</span> Octahedric silicon compound

Hexafluorosilicic acid is an inorganic compound with the chemical formula H
2SiF
6. Aqueous solutions of hexafluorosilicic acid consist of salts of the cation and hexafluorosilicate anion. These salts and their aqueous solutions are colorless.

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

Silver sulfate is the inorganic compound with the formula Ag2SO4. It is a white solid with low solubility in water.

<span class="mw-page-title-main">Silver compounds</span> Chemical compounds containing silver

Silver is a relatively unreactive metal, although it can form several compounds. The common oxidation states of silver are (in order of commonness): +1 (the most stable state; for example, silver nitrate, AgNO3); +2 (highly oxidising; for example, silver(II) fluoride, AgF2); and even very rarely +3 (extreme oxidising; for example, potassium tetrafluoroargentate(III), KAgF4). The +3 state requires very strong oxidising agents to attain, such as fluorine or peroxodisulfate, and some silver(III) compounds react with atmospheric moisture and attack glass. Indeed, silver(III) fluoride is usually obtained by reacting silver or silver monofluoride with the strongest known oxidizing agent, krypton difluoride.

Bromine compounds are compounds containing the element bromine (Br). These compounds usually form the -1, +1, +3 and +5 oxidation states. Bromine is intermediate in reactivity between chlorine and iodine, and is one of the most reactive elements. Bond energies to bromine tend to be lower than those to chlorine but higher than those to iodine, and bromine is a weaker oxidising agent than chlorine but a stronger one than iodine. This can be seen from the standard electrode potentials of the X2/X− couples (F, +2.866 V; Cl, +1.395 V; Br, +1.087 V; I, +0.615 V; At, approximately +0.3 V). Bromination often leads to higher oxidation states than iodination but lower or equal oxidation states to chlorination. Bromine tends to react with compounds including M–M, M–H, or M–C bonds to form M–Br bonds.

<span class="mw-page-title-main">Hexafluorophosphate</span> Anion with the chemical formula PF6–

Hexafluorophosphate is an anion with chemical formula of [PF6]−. It is an octahedral species that imparts no color to its salts. [PF6]− is isoelectronic with sulfur hexafluoride, SF6, and the hexafluorosilicate dianion, [SiF6]2−, and hexafluoroantimonate [SbF6]−. In this anion, phosphorus has a valence of 5. Being poorly nucleophilic, hexafluorophosphate is classified as a non-coordinating anion.

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

Tin(II) fluoride, commonly referred to commercially as stannous fluoride (from Latin stannum, 'tin'), is a chemical compound with the formula SnF2. It is a colourless solid used as an ingredient in toothpastes.

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

Potassium heptafluorotantalate is an inorganic compound with the formula K2[TaF7]. It is the potassium salt of the heptafluorotantalate anion [TaF7]2−. This white, water-soluble solid is an intermediate in the purification of tantalum from its ores and is the precursor to the metal.

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

Vanadium(V) fluoride is the inorganic compound with the chemical formula VF5. It is a colorless volatile liquid. It is a highly reactive compound, as indicated by its ability to fluorinate organic substances.

<span class="mw-page-title-main">Metal halides</span>

Metal halides are compounds between metals and halogens. Some, such as sodium chloride are ionic, while others are covalently bonded. A few metal halides are discrete molecules, such as uranium hexafluoride, but most adopt polymeric structures, such as palladium chloride.

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

Protactinium(V) fluoride is a fluoride of protactinium with the chemical formula PaF5.

References

  1. 1 2 3 4 5 Chemister Chemical Database, Kiper Ruslan Anatolievich, 2002-15. URL: http://chemister.ru/Database/properties-en.php?dbid=1&id=1067
  2. 1 2 Busse, Juliette K.; Stoner, Eric J. (2001). "Silver (I) fluoride". E-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rs016. ISBN   0471936235.
  3. ↑ Sigma-Aldrich Co., Silver(I) fluoride. Retrieved on 2014-05-08.
  4. ↑ "Silver Fluoride". American Elements . Retrieved 2018-09-07.
  5. 1 2 Palmer, William George (1954). Experimental Inorganic Chemistry. CUP Archive. ISBN   9780521059022.
  6. 1 2 Roesky, Herbert W. (2012). Efficient Preparation of Fluorine Compounds. Somerset, New Jersey: Wiley. ISBN   9781118409428.
  7. ↑ Ott, H. (1926). "XI. Die Strukturen von MnO, MnS, AgF, NiS, SnJ4, SrCl2, BaF2; Präzisionsmessungen einiger Alkalihalogenide". Z. Kristallogr. 63 (1–6): 222–230. doi:10.1524/zkri.1926.63.1.222. S2CID   102244646.
  8. 1 2 Bottger, G.L.; Geddes, A.L. (1972). "Lattice Vibrations, Crystal Structure, Dielectric Properties, and Elastic Constants of AgF". J. Chem. Phys. 56 (8): 3735–3739. Bibcode:1972JChPh..56.3735B. doi:10.1063/1.1677770.
  9. ↑ Lozinšek, Matic; Belak Vivod, Matic; Dragomir, Mirela (2023). "Crystal structure reinvestigation of silver(I) fluoride, AgF". IUCR Data. 8 (Pt 1): x230018. doi:10.1107/S2414314623000184. PMC   9912324 . PMID   36794053.
  10. 1 2 Birtcher, R.C.; Deutsch, P.W.; Wendelken, J.F.; Kunz, A.B. (1972). "Valence band structure in silver fluoride". J. Phys. C: Solid State Phys. 5 (5): 562–6. Bibcode:1972JPhC....5..562B. doi:10.1088/0022-3719/5/5/008.
  11. 1 2 3 Hull, S.; Berastegui, P (1998). "High-pressure structural behaviour of silver(I) fluoride". J. Phys.: Condens. Matter. 10 (36): 7945–7955. Bibcode:1998JPCM...10.7945H. doi:10.1088/0953-8984/10/36/005. S2CID   250869196.
  12. ↑ Halleck, P.M.; Jamieson, J.C. (1972). "B1 and B2 phase change of AgF at high pressure". J. Phys. Chem. Solids. 33 (4): 769–773. Bibcode:1972JPCS...33..769H. doi:10.1016/s0022-3697(72)80093-3.
  13. ↑ Jamieson, J.C.; Halleck, P.M.; Roof, R.B.; Pistorius, C.W.F.T. (1975). "Additional polymorphism and non-stoichiometry in AgF". Journal of Physics and Chemistry of Solids. 36 (9): 939–944. Bibcode:1975JPCS...36..939J. doi:10.1016/0022-3697(75)90172-9.
  14. ↑ Marchetti, A.P.; Bottger, G.L. (1971). "Optical Absorption Spectrum of AgF". Physical Review B. 3 (8): 2604–7. Bibcode:1971PhRvB...3.2604M. doi:10.1103/physrevb.3.2604.
  15. ↑ Slayter, Elizabeth (1992). Light and Electron Microscopy. Cambridge University Press. ISBN   9780521339483.
  16. ↑ Hill, Levi L. (1856). A treatise on heliochromy : or, The production of pictures, by means of light, in natural colors. Embracing a full, plain, and unreserved description of the process known as the hillotype, including the author's newly discovered collodio-chrome, or natural colors on collodionized glass ... Getty Research Institute. New York : Robinson & Caswell. p. 143.
  17. ↑ USpatent 3537855,"Photosensitive silver fluoride element",published 1971-11-3
  18. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN   978-0-08-037941-8.
  19. 1 2 Tyrra, Wieland (2002). "Silver(I) fluoride and related compounds in chemical synthesis". Heteroatom Chemistry. 13 (6): 561–566. doi:10.1002/hc.10102.
  20. ↑ Schwartz, Mel (2002). Encyclopedia of Materials, Parts and Finishes (2nd ed.). CRC press. p. 305. ISBN   1420017160.
  21. ↑ Miller, W. T.; Burnard, R. J. (1968). "Perfluoroalkylsilver compounds" "Title". J. Am. Chem. Soc. 90: 7367–7368. doi:10.1021/ja01028a047.
  22. ↑ Muller, Paul; Etienne, Robert; Pfyfer, Jean; Pinenda, Nelson; Schipoff, Michel (1978). "Allylic Reactions of Benzocyclopropenes. Discrimination of Halogen Substituents in 1,l-Dihalogenobenzocyclopropenes". Helvetica Chimica Acta. 61 (7): 2482–8. doi:10.1002/hlca.19780610719.
  23. ↑ Yanagisawa, Akira; Touge, Taichiro; Takayoshi, Arai (2005). "Enantioselective Protonation of Silyl Enolates Catalyzed by a Binap⋅AgF Complex". Angewandte Chemie International Edition. 44 (10): 1546–8. doi:10.1002/anie.200462325. PMID   15645475.
  24. ↑ Guo, Guo-Cong; Zhou, Gong-Du; Wang, Qi-Guang; Mak, Thomas C.W. (1998). "A Fully Encapsulated Acetylenediide in Ag2C2.8AgF". Angewandte Chemie International Edition. 37 (5): 630–2. doi:10.1002/(sici)1521-3773(19980316)37:5<630::aid-anie630>3.0.co;2-k. PMID   29711066.
  25. ↑ Clark, James H. (1980). "Fluoride ion as a base in organic synthesis". Chemical Reviews. 80 (5): 429–452. doi:10.1021/cr60327a004.
  26. ↑ Voorhoeve, R. J. H.; Merewether, J. W. (1972). "Selective Deposition of Silver on Silicon by Reaction with Silver Fluoride Vapor". J. Electrochem. Soc. 119 (3): 364–368. Bibcode:1972JElS..119..364V. doi: 10.1149/1.2404203 .
  27. ↑ Peng, J. J-Y.; Botelho, M.G.; Matinlinna, J.P. (2012). "Silver compounds used in dentistry for caries management: A review". Journal of Dentistry. 40 (7): 531–541. doi:10.1016/j.jdent.2012.03.009. PMID   22484380.
  28. 1 2 Gotjamanos, Theo; Afonso, Fernando (1997). "Unacceptably high levels of fluoride in commercial preparations of silver fluoride". Australian Dental Journal. 42 (1): 52–3. doi: 10.1111/j.1834-7819.1997.tb00097.x . PMID   9078648.
  29. ↑ Gotjamanos, Theo; Orton, Vergil (1998). "Abnormally high fluoride levels in commercial preparations of 40 per cent silver fluoride solution: Contraindications for use in children". Australian Dental Journal. 43 (6): 422–7. doi:10.1111/j.1834-7819.1998.tb00203.x. PMID   9973713.
  30. 1 2 Shah, Shalin; Bhaskar, Visjay; Venkatraghavan, Karthik; Choudhary, Prashant; Trivedi, Krishna; M., Ganesh (2014). "Silver Diamine Fluoride: A Review and Current Applications". Journal of Advanced Oral Research. 5 (1): 25–35. doi: 10.1177/2229411220140106 . S2CID   56987580.
  31. ↑ USpatent 3567823,Yokomizo Ichiro&Yamaga Reiichi,"Silver ammonia fluoride solution and method of its use",published 1971-2-12
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