Silver hexafluorophosphate, sometimes referred to "silver PF-6," is an
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemis ...
with the chemical formula AgPF
6.
Uses and reactions
Silver hexafluorophosphate is a commonly encountered reagent in
inorganic
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemist ...
and
organometallic chemistry
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and s ...
. It is commonly used to replace
halide
In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a flu ...
ligands with the
weakly coordinating hexafluorophosphate
Hexafluorophosphate is an anion with chemical formula of . It is an octahedral species that imparts no color to its salts. is isoelectronic with sulfur hexafluoride, , and the hexafluorosilicate dianion, , and hexafluoroantimonate . In this an ...
anion; the abstraction of the halide is driven by the precipitation of the appropriate
silver halide
A silver halide (or silver salt) is one of the chemical compounds that can form between the Chemical element, element silver (Ag) and one of the halogens. In particular, bromine (Br), chlorine (Cl), iodine (I) and fluorine (F) may each combine wi ...
. Illustrative is the preparation of acetonitrile complexes from a metal bromide, a reaction that would typically be conducted in a solution of
acetonitrile
Acetonitrile, often abbreviated MeCN (methyl cyanide), is the chemical compound with the formula and structure . This colourless liquid is the simplest organic nitrile ( hydrogen cyanide is a simpler nitrile, but the cyanide anion is not clas ...
:
:AgPF
6 + Re(CO)
5Br + CH
3CN → AgBr +
e(CO)5(CH3CN)F
6
AgPF
6 can act as an oxidant, forming silver metal as a by-product. For example, in solution in dichloromethane,
ferrocene
Ferrocene is an organometallic compound with the formula . The molecule is a complex consisting of two cyclopentadienyl rings bound to a central iron atom. It is an orange solid with a camphor-like odor, that sublimes above room temperature, ...
is oxidised to
ferrocenium hexafluorophosphate:
:AgPF
6 + Fe(C
5H
5)
2 → Ag +
e(C5H5)2F
6 (''E'' = 0.65 V)
Related reagents
In terms of their properties and applications,
silver tetrafluoroborate (AgBF
4) and the hexafluoroantimonate (AgSbF
6) are similar to AgPF
6.
Comparison with silver nitrate
Silver nitrate
Silver nitrate is an inorganic compound with chemical formula . It is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides. It was once called ''lunar causti ...
is a traditional and less expensive halide abstraction reagent, as indicated by its widespread use in qualitative tests for halides. Relative to AgPF
6, however, silver nitrate is poorly soluble in weakly basic solvents: the
nitrate
Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insolu ...
anion is Lewis basic and presents an interfering ligand that precludes its use in stringent applications.
References
{{Fluorine compounds
Silver compounds
Hexafluorophosphates