Silver(III) fluoride
Silver(III) fluoride, AgF, 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 AgF units linked into chains by fluoro bridges. Preparation. AgF can be prepared by treating a solution containing tetrafluoroargentate(III) ions 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 AgF overnight at room temperature. The high-valence silver compounds described in the thesis are notable for their variety of colours: KAgF is bright orange, AgF bright red, AgFAsF is deep blue, AgF deep red-brown, and Pd(AgF) is lime-green. Earlier preparations were more heroic, involving the use of krypton difluoride as fluorinating agent, and tended to produce the mixed-valence AgF which may be thought of as silver(II) tetrafluoroargentate(III); AgF, which is (AgF)AgF, is formed by reacting AgF with AgFAsF.