Gold(I) sulfide

Gold(I) sulfide is the inorganic compound with the formula Au₂S. It is the principal sulfide of gold. It decomposes to gold metal and elemental sulfur, illustrating the "nobility" of gold.

Gold(I) sulfide

Gold(I) sulfide unit cell
Names
IUPAC name Gold(I) sulfide
Other names Aurous sulfide
Identifiers
CAS Number	1303-60-2 Y
3D model (JSmol)	Interactive image
ChemSpider	14028556 Y
ECHA InfoCard	100.013.749
EC Number	215-123-7
PubChem CID	22904715
UNII	03VC3O9F7W
CompTox Dashboard (EPA)	DTXSID2061648
InChI InChI=1S/2Au.S/q2*+1;-2 Key: YVIYNOINIIHOCG-UHFFFAOYSA-N
SMILES [S-2].[Au+].[Au+]
Properties
Chemical formula	Au2S
Molar mass	425.998 g/mol
Density	11 g/cm3[1]
Melting point	240 °C (464 °F; 513 K)
Solubility in water	Insoluble
Related compounds
Other anions	Copper(I) sulfide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Structure and preparation

The compound crystallizes in the motif seen for cuprous oxide: gold is 2-coordinate, sulfur 4-coordinate, and the S-Au-S linkage is linear.^[2] Linear coordination geometry is typical of gold(I) compounds, e.g. the coordination complex chloro(dimethyl sulfide)gold(I). The structure is similar to the α form of silver sulfide (argentite), which only exists at high temperatures.^[3]

It can be prepared by treating gold chloride with hydrogen sulfide^[4] It also arises by sulfiding dicyanoaurate:

H₂S + 2 K[Au(CN)₂] → Au₂S + 2 KCN + 2 HCN

This product is described as "initially dark reddish-brown" solid that turns "steel-gray".^[5][3]