Silver(III) fluoride, AgF₃, is an unstable, bright-red, diamagnetic compound containing

silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...

in the unusual +3

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

. Its crystal structure is very similar to that of

gold(III) fluoride Gold(III) fluoride, , is an orange solid that sublimes at 300 °C. It is a powerful fluorinating agent. Preparation AuF3 can be prepared by reacting AuCl3 with F2 or BrF3. Structure The crystal structure of AuF3 consists of spirals ...

: it is a

polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

consisting of rectangular AgF₄ units linked into chains by fluoro bridges.

Preparation

AgF₃ can be prepared by treating a solution containing tetrafluoroargentate(III)

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

s in anhydrous hydrogen fluoride with boron trifluoride; 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 were more heroic, involving the use of

krypton difluoride 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 ...

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

{{Fluorine compounds Fluorides Silver compounds