Chloro(triphenylphosphine)gold(I)

Chlorogold or triphenylphosphinegold chloride is a coordination complex with the formula AuCl. This colorless solid is a common reagent for research on gold compounds.

Preparation and structure

The complex is prepared by reducing chloroauric acid with triphenylphosphine in 95% ethanol:
Chlorogold can also be prepared by treating (dimethyl sulfide)gold(I) chloride AuCl) with triphenylphosphine.
The complex adopts a linear coordination geometry, which is typical of most gold compounds.
It crystallizes in the orthorhombic space group P2₁2₁2₁ with a = 12.300 Å, b = 13.084 Å, c = 10.170 Å with Z = 4 formula units per unit cell.

Reactivity

Triphenylphosphinegold chloride is a precursor to gold catalyst used in organic synthesis. Typically, it is treated with silver salts of weakly coordinating anions to generate a weakly bound Ph₃PAu–X complex. Among these, only the bistriflimide complex Ph₃PAuNTf₂ can be purified. The nitrate complex Ph₃PAuONO₂ and the oxonium species ⁺^– are also prepared from the chloride.
Triphenylphosphinegold chloride is an entry reagent for organogold chemistry. The methyl complex Ph₃PAuMe is prepared from triphenylphosphinegold chloride by transmetalation with a Grignard reagent. Further treatment of Ph₃PAuMe with methyllithium displaces the phosphine ligand and generates lithium dimethylaurate.
[Image:Reaction scheme of gold(I) and gold(III) organometallic compounds (cropped).png|thumb|600px|Methylation of triphenylphosphinegold(I) chloride.|center]