Silver hexafluorophosphate

Silver hexafluorophosphate, sometimes referred to "silver PF-6," is an inorganic compound with the chemical formula AgPF₆.

Uses and reactions

Silver hexafluorophosphate is a commonly encountered reagent in inorganic and organometallic chemistry. It is commonly used to replace halide ligands with the weakly coordinating hexafluorophosphate anion; abstraction of the halide is driven by the precipitation of the appropriate silver halide. Illustrative is the preparation of acetonitrile complexes from a metal bromide, a reaction that would typically be conducted in a solution of acetonitrile:
Ligands with tightly-bound halide atoms coordinate the silver, but do not themselves decompose:
AgPF₆ can act as an oxidant, forming silver metal as a by-product. For example, in solution in dichloromethane, ferrocene is oxidised to ferrocenium hexafluorophosphate:

In terms of their properties and applications, silver tetrafluoroborate and the hexafluoroantimonate are similar to AgPF₆.

Silver nitrate is a traditional and less expensive halide abstraction reagent, as indicated by its widespread use in qualitative tests for halides.
Relative to AgPF₆, however, silver nitrate is poorly soluble in weakly basic solvents: the nitrate anion is Lewis basic and presents an interfering ligand that precludes its use in stringent applications.