Chemistry:Boron sulfide

Boron sulfide

Names
IUPAC name Boron sulfide
Other names Boron sesquisulfide, Diboron trisulfide
Identifiers
CAS Number	12007-33-9 Y
3D model (JSmol)	Interactive image
EC Number	234-504-9
PubChem CID	123269
InChI InChI=1S/B2S3/c3-1-5-2-4 Key: ZVTQDOIPKNCMAR-UHFFFAOYSA-N
SMILES S=BSB=S
Properties
Chemical formula	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
Solubility in water	decomposes
Solubility	soluble in ammonia
Structure
Crystal structure	monoclinic, mP40, SpaceGroup = P21/c, No. 14
Coordination geometry	B: planar, sp2
Thermochemistry
Heat capacity (C)	111.7 J/mol K
Std molar entropy (So298)	327 J/mol K
Std enthalpy of formation (ΔfH⦵298)	-240.6 kJ/mol
Hazards
Main hazards	source of H2S
Safety data sheet	trc-canada.com
GHS pictograms
GHS Signal word	Danger
GHS hazard statements	H225, H260, H311, H301, H318, H315, H335
GHS precautionary statements	P210, P280, P303+361+353, P231+232, P223, P402+404, P302+352, P312, P305+351+338, P405
NFPA 704 (fire diamond)	3 2 3
Flash point	18°C (64.4°F)
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:

B
2S
3 + 3 H
2O → B
2O
3 + 3 H
2S

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:

B
2S
3 + 3 (C
6H
5)
2C=O → B
2O
3 + 3 (C
6H
5)
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 H
2S → B
2S
3 + FeS + 4 H
2

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