Copper(I) bromide is the chemical compound with the formula CuBr. This diamagnetic solid adopts a polymeric structure akin to that for zinc sulfide. The compound is widely used in the synthesis of organic compounds and as a lasing medium in copper bromide lasers.
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| Names | |
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| Other names
Cuprous bromide | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider |
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| ECHA InfoCard | 100.029.210 
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PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| CuBr | |
| Molar mass | 143.45 g/mol |
| Appearance | white powder (see text) |
| Density | 4.71 g/cm3, solid |
| Melting point | 492 °C (918 °F; 765 K) |
| Boiling point | 1,345 °C (2,453 °F; 1,618 K) |
| insoluble; slightly soluble in cold water | |
Solubility product (Ksp) |
6.27×10−9[1] |
| Solubility | soluble in HCl, HBr, ammonium hydroxide, acetonitrile negligible in acetone, sulfuric acid |
| −49.0×10−6 cm3/mol | |
Refractive index (nD) |
2.116 |
| 1.46 D | |
| Hazards | |
| Flash point | Non-flammable |
| NIOSH (US health exposure limits): | |
PEL (Permissible) |
TWA 1 mg/m3 (as Cu)[2] |
REL (Recommended) |
TWA 1 mg/m3 (as Cu)[2] |
IDLH (Immediate danger) |
TWA 100 mg/m3 (as Cu)[2] |
| Related compounds | |
Other anions |
Copper(I) chloride Copper(I) iodide |
Other cations |
Silver(I) bromide Copper(II) bromide Mercury(I) bromide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
The compound is white, although samples are often colored due to the presence of copper(II) impurities.[3] The copper(I) ion also oxidizes easily in air. It is commonly prepared by the reduction of cupric salts with sulfite in the presence of bromide.[4] For example, the reduction of copper(II) bromide with sulfite yields copper(I) bromide and hydrogen bromide:
CuBr is insoluble in most solvents due to its polymeric structure, which features four-coordinated, tetrahedral Cu centers interconnected by bromide ligands (ZnS structure). Upon treatment with Lewis bases, CuBr converts to molecular adducts. For example, with dimethyl sulfide, the colorless complex is formed:[5]
In this coordination complex, the copper is two-coordinate, with a linear geometry. Other soft ligands afford related complexes. For example, triphenylphosphine gives CuBr(P(C6H5)3), although this species has a more complex structure. Thermal excitation of copper(I) bromide vapour yields a blue-violet emission which is of greater saturation than known copper(I) chloride emission.[6] Copper(I) bromide is hence an advantageous emitter in pyrotechnic flames.
In the Sandmeyer reaction, CuBr is employed to convert diazonium salts into the corresponding aryl bromides:[4]
The aforementioned complex CuBr(S(CH3)2) is widely used to generate organocopper reagents.[5] Related CuBr complexes are catalysts for atom transfer radical polymerization and copper-catalyzed cross-dehydrogenative couplings (CDC).
