Caesium auride

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Caesium auride
Caesium Auride.gif
Left: CsAu dissolved in liquid ammonia

Right: Solid CsAu crystals
12256-37-0 N
Jmol interactive 3D Image
Appearance Yellow crystals
Melting point 580 °C (1,076 °F; 853 K)[1]
body-centered cubic
a = 4.24Å[1]
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

Caesium auride (CsAu) is an ionic compound containing the unusual Au ion first discovered in 1978 in the laboratory of Joseph Lagowski.[2] It is obtained by heating a stoichiometric mixture of caesium and gold; the two metallic-yellow liquids react to give a clear product. The solution in liquid ammonia is brown, and the solid is yellow (the colour of both metals making up the compound); the ammonium adduct is dark blue. Despite being a compound of two metals, CsAu lacks metallic properties since the free electrons in both metals are used up, as in all ionic compounds.

The compound reacts violently with water, yielding caesium hydroxide, metallic gold, and hydrogen gas; in liquid ammonia it can be reacted with a caesium-specific ion exchange resin to produce tetramethylammonium auride.[3]


  1. ^ a b Kienast, Gerhard; Verma, Jitendra; Klemm, Wilhelm (June 1961). "Das Verhalten der Alkalimetalle zu Kupfer, Silber und Gold". Zeitschrift für anorganische und allgemeine Chemie (in German) 310 (3): 143–169. doi:10.1002/zaac.19613100304. 
  2. ^ W.J. Peer and J.J. Lagowski (1978), J. Am. Chem. Soc. 100, 6260-6261 Metal-Ammonia Solutions. 11. Au-, a Solvated Transition Metal Anion
  3. ^ Jansen, Martin (2005-11-30). "Effects of relativistic motion of electrons on the chemistry of gold and platinum". Solid State Sciences 7 (12): 1464–1474. doi:10.1016/j.solidstatesciences.2005.06.015.