Gold complexes fluorides

It is dissolved by bromine trifluoride, to form finally gold(III) fluoride, AuFj. This is a notable compound, for in it gold exhibits a simple valency of three, whereas in all other gold(III) compounds, gold is 4-coordinate, usually by complex formation (see below). 

These neutralization processes may be used for the preparation of various complex fluorides without actually isolating the acid or the base. Thus, for example, if equivalent quantities of metallic silver and gold are dissolved in bromine trifluoride and all volatile material is removed in vacuum, the salt AgAuFg remains. The usefulness of this method is increased by the apparent existence in bromine trifluoride solution of both acids and bases which are not sufficiently stable to be isolated. This is well illustrated by the reaction of potassium metaphosphate with bromine trifluoride, which gives a quantitative yield of KPFg ... 

Worth mentioning are chiral gold complexes [20d, e] as well as chiral quaternary ammonium fluorides [21], which are used successfully as catalysts in the asymmetric aldol reaction. 

A novel oxidation state ( + 5) of gold, as represented in the AuFj anion, has recently been established. The complex fluorides Xej F uAuF e, XeFsAuFe, OjAuFj, and Cs AuF6 have been synthesized. More recently the crystal structure of XejFiiAuFj has been determined, revealing that the anion in that salt possesses essentially octahedral symmetry. 

Rubidium metal alloys with the other alkaU metals, the alkaline-earth metals, antimony, bismuth, gold, and mercury. Rubidium forms double haUde salts with antimony, bismuth, cadmium, cobalt, copper, iron, lead, manganese, mercury, nickel, thorium, and 2iac. These complexes are generally water iasoluble and not hygroscopic. The soluble mbidium compounds are acetate, bromide, carbonate, chloride, chromate, fluoride, formate, hydroxide, iodide. 

Krypton difluoride forms complexes with fluorides of many metals, such as arsenic, antimony, tantalum, niobium, gold, and platinum. 

Spectroscopic studies confirm the presence of [AuF6] in most of the above salts, but in [KrF][AuF6l it seems that there is significant interaction between the ions through a bridging fluoride.651,653-655 This complex is prepared by reaction of gold in liquid HF with KrF2.650,651... 

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