Boron sulfide

Boron sulfide
Names
IUPAC name
Boron sulfide
Other names
Boron sesquisulfide, Diboron trisulfide
Identifiers
3D model (JSmol)
ECHA InfoCard 100.031.355 Edit this at Wikidata
EC Number
  • 234-504-9
  • InChI=1S/B2S3/c3-1-5-2-4
    Key: ZVTQDOIPKNCMAR-UHFFFAOYSA-N
  • S=BSB=S
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
111.7 J/mol K
327 J/mol K
-240.6 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
source of H2S
GHS labelling:
GHS02: FlammableGHS06: ToxicGHS07: Exclamation mark
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)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazards (white): no code
2
3
3
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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Infobox references

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.

Reactions

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.

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.

Synthesis

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:

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.

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.

2 B + 3 H2S → B2S3 + 3 H2

Structure

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. The molecular, monomeric, form of B2S3 has a planar V shape with the central B-S-B angle of approximately 120°.


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