Chromium(II) bromide

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Chromium(II) bromide
Kristallstruktur Cadmiumiodid.png
Names
IUPAC name
Chromium(II) bromide
Other names
  • Chromium dibromide
  • Chromium bromide
  • Chromous bromide
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
UNII
  • InChI=1S/2BrH.Cr/h2*1H;/q;;+2/p-2
    Key: XZQOHYZUWTWZBL-UHFFFAOYSA-L
  • [Cr+2].[Br-].[Br-]
Properties
CrBr2
Molar mass 211.804 g·mol−1
AppearanceWhite solid [1]
Density 4.236 g/cm3 [1]
Melting point 842 °C (1,548 °F; 1,115 K) [1]
soluble, exothermal blue solution [1]
Structure
monoclinic [1]
Related compounds
Other anions
Related compounds
 Chromium(III) bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Chromium(II) bromide is the inorganic compound with the chemical formula CrBr2. Like many metal dihalides, CrBr2 adopts the "cadmium iodide structure" motif, i.e., it features sheets of octahedral Cr(II) centers interconnected by bridging bromide ligands. It is a white solid that dissolves in water to give blue solutions that are readily oxidized by air.

Synthesis and reactions

It can be prepared by reduction of chromium(III) bromide with hydrogen gas for 6–10 hours at 350-400 °C, cogenerating hydrogen bromide: [2]

2 CrBr3 + H2 → 2 CrBr2 + 2 HBr

Treatment of chromium powder with concentrated hydrobromic acid gives a blue hydrated chromium(II) bromide, which can be converted to a related acetonitrile complex. [3]

Cr + n H2O + 2 HBr → CrBr2(H2O)n + H2

References

  1. 1 2 3 4 5 Perry, Dale L. (2011). Handbook of Inorganic Compounds, Second Edition. Boca Raton, Florida: CRC Press. p. 120. ISBN   978-1-43981462-8 . Retrieved 2014-01-10.
  2. ↑ Brauer, Georg (1965) [1962]. Handbuch Der Präparativen Anorganischen Chemie [Handbook of Preparative Inorganic Chemistry] (in German). Vol. 2. Stuttgart; New York, New York: Ferdinand Enke Verlag; Academic Press, Inc. p. 1341. ISBN   978-0-32316129-9 . Retrieved 2014-01-10.
  3. ↑ Holah, David G.; Fackler, John P. (1967). "Chromium(II) Salts and Complexes". Inorganic Syntheses. Vol. 10. pp. 26–35. doi:10.1002/9780470132418.ch4. ISBN   9780470131695.
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