Antimony pentasulfide

Antimony pentasulfide

Antimony pentasulfide
CAS number  YesY
ChemSpider  YesY
EC number
ATC code R05
Jmol-3D images Image 1
Molecular formula S5Sb2
Molar mass 403.85 g mol−1
Appearance yellow to orange powder
Density 4.12 g/cm 3
Melting point 135 °C (275 °F; 408 K) (decomposes)
Solubility in water insoluble
Solubility soluble in HCl
soluble in alkalis
EU classification Highly Flammable F
R-phrases R11
Flash point flammable
Related compounds
Related compounds Antimony(III) sulfide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY   YesY/N?)

Antimony pentasulfide is an antimony and sulfur, also known as antimony red. It is a nonstoichiometric compound with a variable composition. Commercial samples are usually are contaminated with sulfur, which may be removed by washing with carbon disulfide in a Soxhlet extractor.


  • Production 1
  • Uses 2
  • Physical chemistry 3
  • References 4


Antimony pentasulfide can be produced by the reaction of antimony with sulfur at a temperature between 250-400 °C in an inert atmosphere.


It may be used as a red pigment and is one possible precursor to Schlippe's Salt, Na3SbS4, which can be prepared according to the equation:

3 Na2S   +   Sb2S5   +   9 H2O   →   2 Na3SbS4·9H2O

Physical chemistry

Like many sulfides, this compound liberates hydrogen sulfide upon treatment with strong acids like hydrochloric acid.[1]

6 HCl   +   Sb2S5   →   2 SbCl3   +   3 H2S   +   2 S

Analysis by Mössbauer spectroscopy indicates that this compound is a derivative antimony(III),[2] explaining the production of antimony(III) chloride, rather than antimony(V) chloride, upon acidification. It is therefore not analogous to the phosphorus(V) compound phosphorus pentasulfide.


  1. ^ Strem MSDS
  2. ^ G. G. Long, J. G. Stevens, L. H. Bowen, S. L. Ruby (1969). "The oxidation number of antimony in antimony pentasulfide". Inorganic and Nuclear Chemistry Letters 5 (1): 21–25.