Silver(II) fluoride
Silberdifluorid
Brown solid
Fixed
4.57 g · cm -3 ( 25 ° C)
690 ° C.
Decomposition at 700 ° C
Risk
-360.0 KJ / mol
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Silver ( II ) fluoride ( Molecular Formula AgF2 ) is the only stable at room temperature, silver (II) salt. Stable oxidation state of the silver is 1, the formation of silver (II ) fluoride is therefore uncommon.
Production and representation
AgF2 is prepared by the reaction of silver with elemental fluorine. At 200 ° C. Silver (I ) fluoride or silver ( I) chloride is also responsive to silver (II ) fluoride. Silver ( II ) fluoride is a strong fluorinating agents and light sensitive. Therefore, it must be Teflon or passivated metal is kept in a container made of quartz glass.
Properties and Structure
Pure silver (II ) fluoride is a white, crystalline powder. Commercial products of dark brown to black color is usually found a fluorine - silver ratio lower than 2, typically 1.75.
About the actual oxidation state of the silver in the silver (II ) fluoride, there was a long time no certainty that there is actually a AgIIF2 or in analogy to the silver (I, III ) oxide, rather than a Tetrafluoroargentat (III) of silver (I) AgI [ AgIIIF4 ] should be formulated. First assumption was confirmed, though at higher temperatures, the Tetrafluoroargentat (III ) structure occurred by neutron scattering research.
However, the compound is paramagnetic at room temperature below its Curie temperature of 110 ° C ferromagnetic.
Silver (II ) fluoride forms with fluorides the intensely colored fluoro complex anions [ AgF3 ] -, [ AgF4 ] 2 - and [ AgF6 ] 4 -.
Use
Silver (II ) fluoride is a very strong fluorinating and oxidizing agents:
- Fluorination and production of organic perfluorocompounds
- Fluorination of aromatic compounds; selective monofluorination is difficult,
- Oxidation of xenon; in this reaction in anhydrous hydrogen fluoride ( HF) is obtained xenon difluoride XeF2,
- Silver ( II) fluoride, carbon monoxide is oxidized to carbonyl fluoride ( COF2 ).
Silver ( II ) fluoride is commercially available, the demand is lower than 100 kg per year. Use, it is mainly used in laboratories; for large-scale industry, it is too expensive at around 1200 U.S. $ / kg ( 1993).