Antimony trisulfide

Antimony trisulfide

Names
IUPAC name diantimony trisulfide, antimony(III) sulfide
Other names antimony sulfide, antimonous sufide, antimony sesquisulfide, antimony vermilion, black antimony, sulphuret of antimony
Identifiers
CAS Number	1345-04-6
Properties
Chemical formula	Sb2S3
Molar mass	339.715
Appearance	grey / black orthorhombic crystal (stibnite)
Density	6.5g cm−3 (stibnite)
Melting point	620 °C (1,148 °F; 893 K) (stibnite)
Vapor pressure	{{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Antimony trisulfide Sb₂S₃ is found in nature as the crystalline mineral stibnite and the amorphous red mineral metastibnite. It is manufactured for use in safety matches, military ammunition, explosives and fireworks. It also is used in the production of ruby-colored glass and in plastics as a flame retardant. Historically the stibnite form was used as a grey pigment in paintings produced in the 16th century. It is a semiconductor with a direct band gap of 1.8-2.5 eV. With suitable doping p and n type materials can be produced.

Preparation and reactions

Sb₂S₃ can be prepared from the elements at temperature 500-900 °C:

2Sb + 3S → Sb₂S₃

Sb₂S₃ is precipitated when H₂S is passed through an acidified solution of Sb(III). This reaction has been used as a gravimetric method for determining antimony, bubbling H₂S through a solution of Sb(III) compound in hot HCl deposits an orange form of Sb₂S₃ which turns black under the reaction conditions.

Sb₂S₃ is readily oxidised, reacting vigorously with oxidising agents. It burns in air with a blue flame. It reacts with icandescence with cadmium, magnesium and zinc chlorates. Mixtures of Sb₂S₃ and chlorates may explode.

In the extraction of antimony from antimony ores the alkaline sulfide process is employed where Sb₂S₃ reacts to form thioantimonate(III) salts (also called thioantimonite):

3Na₂S + Sb₂S₃ → 2Na₃SbS₃

A number of salts containing different thioantimonate(III) ions can be prepared from Sb₂S₃ these include:

[SbS₃]³⁻, [SbS₂]⁻, [Sb₂S₅]⁴⁻, [Sb₄S₉]⁶⁻, [Sb₄S₇]²⁻ and [Sb₈S₁₇]¹⁰⁻

"Schlippe's salt", Na₃SbS₄·9H₂O, a thioantimonate(V) salt is formed when Sb₂S₃ is boiled with sulfur and sodium hydroxide. The reaction can be represented as:

Sb₂S₃ + 3S²⁻ + 2S → 2[SbS₄]³⁻

Structure

The structure of the black needle like form of Sb₂S₃, stibnite, consists of linked ribbons in which antimony atoms are in two different coordination environments, trigonal pyramidal and square pyramidal. Similar ribbons occur in Bi₂S₃ and Sb₂Se₃. The red form, metastibnite, is amorphous. Recent work suggests that there are a number of closely related temperature dependant structures of stibnite which have been termed stibnite(I) the high temperature form, identified previously, stibnite (II) and stibnite(III).