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Boron sulfide is the chemical compound with the formula B2S3. It is a white, moisture-sensitive solid. It has a polymeric structure. The material has been of interest as a component of "high-tech" glasses and as a reagent for preparing organosulfur compounds.
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| Names | |
|---|---|
| IUPAC name
Boron sulfide | |
| Other names
Boron sesquisulfide, Diboron trisulfide | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.031.355 |
| EC Number |
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PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |
| B2S3 | |
| Molar mass | 117.80 g/mol |
| Appearance | colorless crystals |
| Density | 1.55 g/cm3, solid |
| Melting point | 563 °C (1,045 °F; 836 K) |
| Boiling point | decomposes at high T |
| decomposes | |
| Solubility | soluble in ammonia |
| Structure | |
| monoclinic, mP40, SpaceGroup = P21/c, No. 14 | |
| B: planar, sp2 | |
| Thermochemistry | |
Heat capacity (C) |
111.7 J/mol K |
Std molar entropy (S⦵298) |
327 J/mol K |
Std enthalpy of formation (ΔfH⦵298) |
-240.6 kJ/mol |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards |
source of H2S |
| GHS labelling: | |
   | |
| Danger | |
| H225, H260, H301, H311, H315, H318, H335 | |
| P210, P223, P231+P232, P280, P302+P352, P303+P361+P353, P305+P351+P338, P312, P402+P404, P405 | |
| NFPA 704 (fire diamond) | |
| Flash point | 18°C (64.4°F) |
| Safety data sheet (SDS) | trc-canada.com |
| Related compounds | |
Related compounds |
BCl3 Lawesson's reagent |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Like the sulfides of silicon and phosphorus, B2S3 reacts with traces of water, including atmospheric moisture to release H2S. This hydrolysis is described by the following idealized equation:
- B2S3 + 3 H2O → B2O3 + 3 H2S
B2S3 readily forms glasses when blended with other sulfides such as P4S10. Such glasses do not absorb mid-frequencies of Infra-red energy relative to conventional borosilicate glasses. Some of these ternary phases that are fast ion conductors.[2]
B2S3 converts ketones into the corresponding thiones. For example, the conversion of benzophenone to its thione proceeds as follows:
- B2S3 + 3 (C6H5)2C=O → B2O3 + 3 (C6H5)2C=S
In practice, B2S3 would be used in excess.[3]
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An early synthesis involved the reaction of iron and manganese borides with hydrogen sulfide at temperatures of 300 °C. The conversion is shown for the monoborides in the following idealized equation:[4]
- 2 FeB + 4 H2S → B2S3 + FeS + 4 H2
The first synthesis was done by Jöns Jakob Berzelius in 1824 by direct reaction of amorphous boron with sulfur vapor.[5]
- 2 B + 3 S → B2S3
Another synthesis was favoured by Friedrich Wöhler and Henri Etienne Sainte-Claire Deville first published in 1858, starting from boron and hydrogen sulfide.[6][7]
- 2 B + 3 H2S → B2S3 + 3 H2
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The boron atoms in B2S3 are trigonal planar, and are arranged in B3S3 and B2S2 rings with bridging S atoms forming a layer structure with an interlayer distance of 355 pm. This is different from boron trioxide which has a three dimensional structure.[8] The molecular, monomeric, form of B2S3 has a planar V shape with the central B-S-B angle of approximately 120°.[8]
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