Gold(I,III) chloride

Gold(I,III) chloride
Names
	Systematic IUPAC name tetra-μ-chlorotetrachlorotetragold
	Other names Mixed gold chloride, Tetragold octachloride
Identifiers
CAS Number	62792-24-9 ;
3D model (JSmol)	Interactive image; Interactive image;
	InChI InChI=1S/4Au.4ClH.4Cl/h;;;;41H;;;;/q;;2+2;;;;;;;;/p-4 Key: NWBJVUUFMJPGPV-UHFFFAOYSA-J ;
	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).
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	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[1] or carbon monoxide[2] 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 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).

References

Dell'Amico, Daniela Belli; Calderazzo, Fausto; Marchetti, Fabio; Merlino, Stefano; Perego, Giovanni (1977). "X-Ray crystal and molecular structure of Au₄Cl₈, the product of the reduction of Au₂Cl₆ by Au(CO)Cl". Journal of the Chemical Society, Chemical Communications (1): 31. doi:10.1039/C39770000031.
Dell'Amico, Daniela Belli; Calderazzo, Fausto; Marchetti, Fabio; Merlino, Stefano (1982). "Synthesis and molecular structure of [Au₄Cl₈], and the isolation of [Pt(CO)Cl₅]⁻ in thionyl chloride". Journal of the Chemical Society, Dalton Transactions (11): 2257. doi:10.1039/DT9820002257.

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[XRD-1] Dell'Amico, Daniela Belli; Calderazzo, Fausto; Marchetti, Fabio; Merlino, Stefano; Perego, Giovanni (1977). "X-Ray crystal and molecular structure of Au₄Cl₈, the product of the reduction of Au₂Cl₆ by Au(CO)Cl". Journal of the Chemical Society, Chemical Communications (1): 31. doi:10.1039/C39770000031.

[optimised-2] Dell'Amico, Daniela Belli; Calderazzo, Fausto; Marchetti, Fabio; Merlino, Stefano (1982). "Synthesis and molecular structure of [Au₄Cl₈], and the isolation of [Pt(CO)Cl₅]⁻ in thionyl chloride". Journal of the Chemical Society, Dalton Transactions (11): 2257. doi:10.1039/DT9820002257.