Chloro(triphenylphosphine)gold(I) or triphenylphosphinegold(I) chloride is a
coordination complex
A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as '' ligands'' or complexing agents. ...
with the formula (
Ph3P)AuCl. This colorless solid is a common reagent for research on gold compounds.
Preparation and structure
The complex is prepared by reducing
chloroauric acid
Chloroauric acid is an inorganic compound with the chemical formula . It forms hydrates . Both the trihydrate and tetrahydrate are known. Both are orange-yellow solids consisting of the planar anion. Often chloroauric acid is handled as a soluti ...
with
triphenylphosphine
Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists ...
in 95%
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
:
:HAuCl
4 + H
2O + 2 PPh
3 → (Ph
3P)AuCl + Ph
3PO + 3 HCl
Ph
3PAuCl can also be prepared by treating a thioether complex of gold like (dimethyl sulfide)gold(I) chloride,
Me2S)AuCl with triphenylphosphine.
The complex adopts a linear coordination geometry, which is typical of most gold(I) compounds.
It crystallizes in the orthorhombic space group ''P''2
12
12
1 with a = 12.300(4) Å, b = 13.084(4) Å, c = 10.170(3) Å with Z = 4 formula units per unit cell.
Reactivity
Triphenylphosphinegold(I) chloride is a popular stable precursor for a cationic gold(I) catalyst used in organic synthesis.
Typically, it is treated with silver(I) salts of weakly coordinating anions (e.g., X
– = SbF
6–, BF
4–, TfO
–, or Tf
2N
–) to generate a weakly bound Ph
3PAu–X complex, in equilibrium with the catalytically-active species
h3PAusup>+X
– in solution. Among these, only the
bistriflimide complex Ph
3PAuNTf
2 can be isolated as the pure compound. The
nitrate complex Ph
3PAuONO
2 and the
oxonium species
Ph3PAu)3Osup>+
F4sup>– are also prepared from the chloride.
As shown in the scheme below, the methyl complex Ph
3PAuMe is prepared from triphenylphosphinegold(I) chloride by transmetalation with a Grignard reagent. Further treatment of Ph
3PAuMe with methyllithium displaces the phosphine ligand and generates lithium di- and tetramethylaurate, Li
+ uMe2sup>– and Li
+ uMe4sup>–, respectively.
References
{{Gold compounds
Triphenylphosphine complexes
Gold(I) compounds
Chlorides
Chloro complexes
Gold–halogen compounds