Dibromine monoxide


Dibromine monoxide
Dibromine monoxide.png
IUPAC name
Dibromine monoxide
Systematic IUPAC name
Other names
Dibromine oxide, bromine monoxide
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3D model (JSmol)
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  • 10686917
  • 14513628
  • InChI=1S/Br2O/c1-3-2
  • O(Br)Br
Molar mass 175.807 g/mol
Appearance dark brown solid
Melting point decomposes around −17.5°C[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Dibromine monoxide is the chemical compound composed of bromine and oxygen with the formula Br2O. It is a dark brown solid which is stable below −40°C and is used in bromination reactions.[1] It is similar to dichlorine monoxide, the monoxide of its halogen neighbor one period higher on the periodic table. The molecule is bent, with C2v molecular symmetry. The Br−O bond length is 1.85Å and the Br−O−Br bond angle is 112°,[2][3] similar to dichlorine monoxide.


Dibromine monoxide can be prepared by reacting bromine vapor or a solution of bromine in carbon tetrachloride with mercury(II) oxide at low temperatures:[1][3]

2 Br2 + 2 HgOHgBr2·HgO + Br2O

It can also be formed by thermal decomposition of bromine dioxide[2] or by passing an electrical current through a 1:5 mixture of bromine and oxygen gases.[3]


  1. ^ a b c Perry, Dale L.; Phillips, Sidney L. (1995), Handbook of Inorganic Compounds, CRC Press, p. 74, ISBN 0-8493-8671-3, retrieved 25 August 2015
  2. ^ a b Levason, William; Ogden, J. Steven; Spicer, Mark D.; Young, Nigel A. (January 1990). "Characterization of dibromine monoxide (Br2O) by bromine K-edge EXAFS and IR spectroscopy". Journal of the American Chemical Society. 112 (3): 1019–1022. doi:10.1021/ja00159a019.
  3. ^ a b c Wiberg, Egon (2001). Wiberg, Nils (ed.). Inorganic chemistry (1st ed.). San Diego, Calif.: Academic Press. p. 464. ISBN 9780123526519.