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Caesium auride

Solution of CsAu(left), pure CsAu(right)
Names
IUPAC name Caesium auride
Identifiers
CAS Number	12256-37-0
3D model (JSmol)	covalent form: Interactive image ionic form: Interactive image
ChemSpider	65322210
PubChem CID	71308168
InChI InChI=1S/Au.CsKey: COOMJVRPVOQALF-UHFFFAOYSA-N
SMILES covalent form: ionic form: .
Properties
Chemical formula	AuCs
Molar mass	329.872022 g·mol
Appearance	Yellow crystals
Melting point	580 °C (1,076 °F; 853 K)
Solubility in water	reacts violently
Structure
Crystal structure	CsCl
Lattice constant	a = 4.24 Å
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). N verify (what is  ?) Infobox references

Caesium auride is the inorganic compound with the formula CsAu. It is the Cs salt of the unusual Au anion.

Preparation and reactions

CsAu is obtained by heating a stoichiometric mixture of caesium and gold. The two metallic-yellow liquids react to give a transparent yellow product. Despite being a compound of two metals, CsAu lacks metallic properties since it is a salt with localized charges; it instead behaves as a semiconductor with band gap 2.6 eV.

The compound hydrolyzes readily, yielding caesium hydroxide, metallic gold, and hydrogen.

2 CsAu + 2 H₂O → 2 CsOH + 2 Au + H₂

The solution in liquid ammonia is brown, and the ammonia adduct CsAu·NH₃ is blue; the latter has ammonia molecules intercalated between layers of the CsAu crystal parallel to the (110) plane. Solutions undergo metathesis with tetramethylammonium loaded ion exchange resin to give tetramethylammonium auride.

References

1. ^ 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. Peer, William J.; Lagowski, J. J. (1978). "Metal-Ammonia Solutions. 11. Au, a Solvated Transition Metal Anion". J. Am. Chem. Soc. 100: 6260–6261. doi:10.1021/ja00487a064.
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. Bibcode:2005SSSci...7.1464J. doi:10.1016/j.solidstatesciences.2005.06.015.
4. Norrby, Lars J. (February 1991). "Why is mercury liquid? Or, why do relativistic effects not get into chemistry textbooks?". Journal of Chemical Education. 68 (2): 110. Bibcode:1991JChEd..68..110N. doi:10.1021/ED068P110.

Further reading

• Jansen, Martin (2008). "The chemistry of gold as an anion". Chemical Society Reviews. 37 (9): 1826–1835. doi:10.1039/B708844M. PMID 18762832.—includes photograph of the compound.

• Gold(−I) compounds
• Caesium compounds
• Semiconductor materials
• Caesium chloride crystal structure