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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.

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
3D model (JSmol)
Properties
Au
4
Cl
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

SynthesisEdit

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 propertiesEdit

Single crystals of gold(I,III) chloride are triclinic with a P1 space group and consist of discrete Au4Cl8 molecules with idealised C2h 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).

ReferencesEdit

  1. ^ a b 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.
  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.