Chemistry:Silver(III) fluoride

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Short description: Unstable silver compound in the unusual +3 oxidation state
Silver(III) fluoride
Crystal structure of AuF3.png
Names
IUPAC name
Silver(III) fluoride
Other names
Silver trifluoride
Argentic fluoride
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
100808
Properties
AgF3
Molar mass 164.86 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Silver(III) fluoride, AgF3, is an unstable, bright-red, diamagnetic compound containing silver in the unusual +3 oxidation state. Its crystal structure is very similar to that of gold(III) fluoride: it is a polymer consisting of rectangular AgF4 units linked into chains by fluoro bridges.[1]

Preparation

AgF3 can be prepared by treating a solution containing tetrafluoroargentate(III) ions in anhydrous hydrogen fluoride with boron trifluoride;[2] the potassium tetrafluoroargentate(III) was prepared by heating a stoichiometric mix of potassium and silver nitrate in a sealed container filled with pressurised fluorine gas at 400C for 24 hours, twice. When dissolved in anhydrous HF, it decomposes spontaneously to Ag3F8 overnight at room temperature. The high-valence silver compounds described in the thesis are notable for their variety of colours: KAgF4 is bright orange, AgF3 bright red, AgFAsF6 is deep blue, Ag3F8 deep red-brown, and Pd(AgF4)2 is lime-green.

Earlier preparations used krypton difluoride as fluorinating agent, and tended to produce the mixed-valence Ag3F8 which may be thought of as silver(II) tetrafluoroargentate(III); Ag2F5, which is (AgF)+AgF4, is formed by reacting AgF3 with AgFAsF6.

References

  1. Zemva, Boris; Lutar, Karel; Jesih, Adolf; Casteel, William J.; Wilkinson, Angus P.; Cox, David E.; von Dreele, Robert B.; Borrmann, Horst et al. (1991). "Silver Trifluoride: Preparation, Crystal Structure, Some Properties, and Comparison with AuF3". J Am Chem Soc 113 (11): 4192–4198. doi:10.1021/ja00011a021. 
  2. Casteel, William (September 1992). The Synthesis and Structural Characterization of Novel Transition Metal Fluorides (PhD).