Gold(I,III) chloride

Gold(I,III) chloride

Skeletal formula of gold(I,III) chloride with implicit oxidation states shown
Names
Systematic IUPAC name tetra-μ-chlorotetrachlorotetragold
Other names Mixed gold chloride, Tetragold octachloride
Identifiers
CAS Number	62792-24-9 Y
Jmol 3D model	Interactive image Interactive image
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 a black solid with the chemical formula Au₄Cl₈. It is an example of a mixed valence compound as it contains gold in two different oxidation states; square-planar gold(III) and almost linear gold(I). The compound must be handled carefully as it is photosensitive as well as extremely air and moisture sensitive.

Synthesis

Gold(I,III) chloride may be prepared by the reaction of gold(III) chloride with gold carbonyl chloride or carbon monoxide at room temperature in thionyl chloride.

Au₂(CO)Cl₄ + Au₂Cl₆ → COCl₂ + Au₄Cl₈

2 Au₂Cl₆ + 2 CO → Au₄Cl₈ + 2 COCl₂

Structure and properties

Single crystals of gold(I,III) chloride are triclinic with a P1 space group and consist of discrete Au₂Cl₆ molecules with idealised C_2h symmetry. 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 bidging chlorides (2.33 Å) being slightly longer than those of terminal chlorides (2.24 Å).