Caesium auride

Caesium auride
Names


Solution of CsAu(left), pure CsAu(right)
IUPAC name Caesium auride
Identifiers
CAS Number	12256-37-0^Y
3D model (JSmol)	covalent form: Interactive image ionic form: Interactive image
PubChem CID	71308168
InChI InChI=1S/Au.Cs^N Key: COOMJVRPVOQALF-UHFFFAOYSA-N^N
SMILES covalent form: [Cs] [Au] ionic form: [Cs+].[Au-]
Properties
Chemical formula	AuCs
Molar mass	329.872022 g·mol⁻¹
Appearance	Yellow crystals
Melting point	580 °C (1,076 °F; 853 K)^[1]
Solubility in water	reacts violently
Structure
Crystal structure	CsCl
Lattice constant	a = 4.24 Å^[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is ^YN ?) Infobox references

Chemical compound

Caesium auride is the inorganic compound with the formula CsAu. It is the Cs⁺ salt of the unusual Au⁻ anion.^[2]

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.^[3] 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.^[4]

The compound hydrolyzes readily, yielding caesium hydroxide, metallic gold, and hydrogen.^[3]

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.^[3]

References

^ ^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.
^ 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.
^ ^a ^b ^c 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.
^ 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.