Silver (II) fluoride

Structural formula
General
Surname	Silver (II) fluoride
other names	Silver difluoride
Molecular formula	AgF 2
Brief description	brown solid
External identifiers / databases
EC number	232-037-5
ECHA InfoCard	100.029.124
PubChem	11542804
ChemSpider	74201
Wikidata	Q425222
properties
Molar mass	145.87 g mol −1
Physical state	firmly
density	4.57 g cm −3 (25 ° C)
Melting point	690 ° C
boiling point	Decomposes at 700 ° C
solubility	Decomposes in water
safety instructions
H and P phrases	H: 272-301 + 311 + 331-314
	P: 220-261-280-301 + 310-305 + 351 + 338-310
Thermodynamic properties
ΔH f 0	−360.0 kJ / mol
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Silver (II) fluoride (empirical formula AgF ₂ ) is the only silver (II) salt that is stable at room temperature. The stable oxidation state of silver is +1, so the formation of silver (II) fluoride is unusual.

Extraction and presentation

AgF ₂ is made by the reaction of silver with elemental fluorine :

{\ displaystyle {\ ce {Ag + F2 -> AgF2}}}

At 200 ° C, silver (I) fluoride or silver (I) chloride also reacts to form silver (II) fluoride:

{\ displaystyle {\ ce {2 AgCl + 2 F2 -> 2 AgF2 + Cl2}}}

Silver (II) fluoride is a strong fluorinating agent and sensitive to light. It must therefore be stored in Teflon , passivated metal or in a container made of quartz glass.

Properties and structure

Pure silver (II) fluoride is a white, crystalline and hygroscopic powder. In commercial products of dark, brown to black coloration, one usually finds a fluorine-silver ratio below 2, typically 1.75.

For a long time there was no certainty about the actual oxidation state of silver in silver (II) fluoride, whether it was actually as Ag ^II F ₂ or in analogy to silver (I, III) oxide rather than a tetrafluoroargentate (III) of silver (I ) Ag ^I [Ag ^III F ₄ ] is to be formulated. The former assumption was confirmed by neutron scattering studies , although the tetrafluoroargentate (III) structure also occurred at higher temperatures.

The compound is solid at room temperature paramagnetic , below their Curie temperature of -110 ° C, however, ferromagnetic .

Silver (II) fluoride and fluorides form the intensely colored fluorocomplex anions [AgF ₃ ] ^- , [AgF ₄ ] ²⁻ and [AgF ₆ ] ⁴⁻ .

use

Silver (II) fluoride is a very strong fluorinating and oxidizing agent:

Fluorination and production of organic perfluorocompounds,
Fluorination of aromatic compounds; selective monofluorination is difficult,
Oxidation of xenon ; this reaction in anhydrous hydrogen fluoride (HF) gives xenon difluoride XeF ₂ ,
Silver (II) fluoride oxidizes carbon monoxide to carbonyl fluoride (COF ₂ ).

Silver (II) fluoride is commercially available, but the demand is less than 100 kg per year. It is mainly used in laboratories; for large industry it is too expensive at around US $ 1200 / kg (1993).

Individual evidence

↑ ^a ^b ^c data sheet silver (II) fluoride from AlfaAesar, accessed on December 15, 2010 ( PDF )(JavaScript required) .
↑ ^a ^b ^c data sheet Silver (II) fluoride from Sigma-Aldrich , accessed on April 23, 2011 ( PDF ).
↑ ^a ^b ^c Homer F. Priest: Anhydrous metal fluorides . In: Ludwig F. Audrieth (Ed.): Inorganic Syntheses . tape 3 . McGraw-Hill, Inc., 1950, pp. 171-183 (English).
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-4.
↑ JT Wolan, GB Hoflund: Surface Characterization Study of AgF and AgF2 Powders Using XPS and ISS , in: Applied Surface Science 1998 , 125 .
↑ H.-C. Miller, A. Schultz, M. Hargittai: Structure and Bonding in Silver Halides: A Quantum ... X = F, Cl, Br, I. In: Journal of the American Chemical Society (2005), 127 .
↑ D. Rausch, R. Davis, DW Osborne: The Addition of Fluorine to Halogenated Olefins by Means of Metal Fluorides. In: Journal of Organic Chemistry (1962) 28 , pp. 494-497
^ A. Zweig, RG Fischer, J. Lancaster: New Methods for Selective Monofluorination of Aromatics Using Silver Difluoride. In: Journal of Organic Chemistry (1980), 45 .
↑ J. Levec, J. Slivnik, B. Zemva: On the Reaction Between Xenon and Fluorine. In: Journal of Inorganic and Nuclear Chemistry , (1974) Volume 36 .

[alfa-1] ta sheet silver (II) fluoride from AlfaAesar, accessed on December 15, 2010 ( PDF )(JavaScript required) .

[Sigma-2] ta sheet Silver (II) fluoride from Sigma-Aldrich , accessed on April 23, 2011 ( PDF ).

[IS3-3] Homer F. Priest: Anhydrous metal fluorides . In: Ludwig F. Audrieth (Ed.): Inorganic Syntheses . tape 3 . McGraw-Hill, Inc., 1950, pp. 171-183 (English).

[CRC90_5_4-4] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-4.

[5] JT Wolan, GB Hoflund: Surface Characterization Study of AgF and AgF2 Powders Using XPS and ISS , in: Applied Surface Science 1998 , 125 .

[6] H.-C. Miller, A. Schultz, M. Hargittai: Structure and Bonding in Silver Halides: A Quantum ... X = F, Cl, Br, I. In: Journal of the American Chemical Society (2005), 127 .

[7] D. Rausch, R. Davis, DW Osborne: The Addition of Fluorine to Halogenated Olefins by Means of Metal Fluorides. In: Journal of Organic Chemistry (1962) 28 , pp. 494-497

[8] A. Zweig, RG Fischer, J. Lancaster: New Methods for Selective Monofluorination of Aromatics Using Silver Difluoride. In: Journal of Organic Chemistry (1980), 45 .

[9] J. Levec, J. Slivnik, B. Zemva: On the Reaction Between Xenon and Fluorine. In: Journal of Inorganic and Nuclear Chemistry , (1974) Volume 36 .