Bismuth tribromide

Bismuth tribromide is an inorganic compound of bismuth and bromine with the chemical formula BiBr₃.

Bismuth tribromide

α polymorph β polymorph
Names
IUPAC name bismuth bromide
Other names bismuth tribromide tribromobismuth tribromobismuthine tribromobismuthane bismuth(III) bromide
Identifiers
CAS Number	7787-58-8
3D model (JSmol)	Interactive image
ChemSpider	74210
ECHA InfoCard	100.029.201
EC Number	232-121-1
PubChem CID	82232
UNII	DT59198T2X
CompTox Dashboard (EPA)	DTXSID8064850
InChI InChI=1S/Bi.3BrH/h;3*1H/q+3;;;/p-3 Key: TXKAQZRUJUNDHI-UHFFFAOYSA-K InChI=1/Bi.3BrH/h;3*1H/q+3;;;/p-3 Key: TXKAQZRUJUNDHI-DFZHHIFOAX
SMILES Br[Bi](Br)Br
Properties
Chemical formula	BiBr3
Molar mass	448.692 g·mol−1
Appearance	white to light yellow or golden deliquescent crystals[1]
Density	5.72 g/cm3 at 25 °C[1]
Melting point	219 °C (426 °F; 492 K) [1]
Boiling point	462 °C (864 °F; 735 K) [1]
Solubility in water	Soluble, slow hydrolysis
Solubility	diethyl ether, THF
Magnetic susceptibility (χ)	-147.0·10−6 cm3/mol
Thermochemistry
Std enthalpy of formation (ΔfH⦵298)	−276[1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	corrosive[2]
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314
Precautionary statements	P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
NFPA 704 (fire diamond)	3 0 1
Related compounds
Other anions	bismuth trifluoride bismuth trichloride bismuth triiodide
Other cations	nitrogen tribromide phosphorus tribromide arsenic tribromide antimony tribromide aluminium tribromide iron(III) bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

It may be formed by the reaction of bismuth oxide and hydrobromic acid.^[1]

Bi₂O₃ + 6 HBr ⇌ 2 BiBr₃ + 3 H₂O

Bismuth tribromide can also be produced by the direct oxidation of bismuth in bromine.^[1]

2 Bi + 3 Br₂ → 2 BiBr₃

Structure

Bismuth tribromide adopts two different structures in the solid state: a low-temperature polymorph α-BiBr₃ that is stable below 158 °C and a high-temperature polymorph β-BiBr₃ that is stable above this temperature. Both polymorphs are monoclinic, but α-BiBr₃ is in space group P2₁/a whereas β-BiBr₃ is in C2/m. α-BiBr₃ consists of pyramidal molecules whereas β-BiBr₃ is polymeric and adopts the AlCl₃ structure. BiBr₃ is the only group 15 trihalide that can adopt both molecular and polymeric structures.^[3]

Reactivity

Bismuth bromide is highly water-soluble. It is a Lewis acid and accepts bromide ions to form monomeric and oligomeric anionic complexes (bromobismuthates), e.g. [BiBr₆]³⁻, [Bi₂Br₁₀]⁴⁻, (BiBr⁻
₄)_n and (BiBr²⁻
₅)_n.^[4]

References

1. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 558–561. ISBN 978-0-08-037941-8.
2. "Sigma-Aldrich: 654981 Bismuth(III) bromide anhydrous, powder, 99.999% trace metals basis". Archived from the original on 2012-02-11.
3. von Benda, Heike (1980). "Zur Polymorphie des Wismuttribromids". Zeitschrift für Kristallographie - Crystalline Materials. 151 (1–4): 271–286. doi:10.1524/zkri.1980.151.14.271. S2CID 96552131.
4. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 564–568. ISBN 978-0-08-037941-8.