Gold(I,III) chloride

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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 (Jmol)
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

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[edit]

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[edit]

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

References[edit]

  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.