Arsenic triselenide

Arsenic triselenide
Names
	Other names Arsenic(III) selenide
Identifiers
CAS Number	1303-36-2 ;
3D model (JSmol)	Interactive image;
ChemSpider	14089 ;
ECHA InfoCard	100.013.745
EC Number	215-119-5;
PubChem CID	14772;
RTECS number	CG2285000;
UNII	XWS0W0GB8G;
CompTox Dashboard (EPA)	DTXSID7061645 ;
	InChI InChI=1S/As2Se3/c3-1-5-2-4 Key: WBFMCDAQUDITAS-UHFFFAOYSA-N ; InChI=1/As2Se3/c3-1-5-2-4 Key: WBFMCDAQUDITAS-UHFFFAOYAQ;
	SMILES [Se]=[As][Se][As]=[Se];
Properties
Chemical formula	As2Se3
Molar mass	386.756 g·mol−1
Appearance	brown-black powder or metallic gray crystals
Odor	odorless
Density	4.75 g/cm3
Melting point	377 °C (711 °F; 650 K)
Solubility in water	insoluble
Structure
Crystal structure	Monoclinic, mP20
Space group	P21/c, No. 14
Lattice constant	a = 0.43 nm, b = 0.994 nm, c = 1.29058 nm α = 90°, β = 109.927°, γ = 90°
Formula units (Z)	4
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H330, H331, H373, H410
Precautionary statements	P260, P261, P264, P270, P271, P273, P284, P301+P310, P304+P340, P310, P311, P314, P320, P321, P330, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)	4 0 0
Related compounds
Other anions	diarsenic trioxide; diarsenic trisulfide; arsenic(III) telluride;
Other cations	antimony(III) selenide
Related compounds	arsenic(V) selenide
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Arsenic triselenide is an inorganic chemical compound with the chemical formula As₂Se₃.

Amorphous arsenic triselenide is used as a chalcogenide glass for infrared optics. When purified, it transmits light with wavelengths between ca. 0.7 and 19 μm.

In arsenic triselenide, arsenic is covalently bonded to selenium, where arsenic has a formal oxidation state of +3, and selenium −2.