Gold(I,III) chloride

Names
Systematic IUPAC name tetra-μ-chlorotetrachlorotetragold
Other names Mixed gold chloride, Tetragold octachloride
Identifiers
CAS Number	62792-24-9 Y
3D model (JSmol)	Interactive image Interactive image
PubChem CID	139092506
InChI InChI=1S/4Au.4ClH.4Cl/h;;;;4*1H;;;;/q;;2*+2;;;;;;;;/p-4 N Key: NWBJVUUFMJPGPV-UHFFFAOYSA-J N
SMILES Cl[Au]1(Cl)[Cl][Au][Cl][Au](Cl)(Cl)[Cl][Au][Cl]1 [Cl-].[Cl-].[Cl-].[Cl-].[Cl-].[Cl-].[Cl-].[Cl-].[Au+].[Au+].[Au+3].[Au+3]
Properties
Chemical formula	Au 4Cl 8
Molar mass	1071.490 g mol−1
Appearance	black crystals
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Gold(I,III) chloride is the inorganic compound with the chemical formula Au₄Cl₈. It is an example of a mixed valence compound as it contains gold in two oxidation states; square-planar gold(III) and almost linear gold(I). The compound, which is black, is photosensitive as well as air- and moisture-sensitive.

According to the procedure by Calderazzo et al., gold(I,III) chloride may be prepared by the reaction of gold(III) chloride with gold carbonyl chloride^[1] or carbon monoxide^[2] at room temperature in thionyl chloride.

Au₂(CO)Cl₄ + Au₂Cl₆ → COCl₂ + Au₄Cl₈

2 Au₂Cl₆ + 2 CO → Au₄Cl₈ + 2 COCl₂

Single crystals of gold(I,III) chloride are triclinic with a P1 space group and consist of discrete Au₄Cl₈ molecules with idealised C_2h symmetry.^[1] Within this the Au(I) centers are linearly coordinated with a Cl-Au-Cl bond angle of 175.0° (close to the ideal value of 180°) and an average bond length of 2.30 Å. The Au(III) centers adopt a slightly irregular square-planar conformation with the Au-Cl bond lengths for bridging chlorides (2.33 Å) being slightly longer than those of terminal chlorides (2.24 Å).