Dibromine monoxide

Dibromine monoxide

Names
IUPAC name Dibromine monoxide
Other names Dibromine oxide, bromine monoxide
Identifiers
CAS Number	21308-80-5
Properties
Chemical formula	Br2O
Molar mass	175.807 g/mol
Appearance	dark brown solid
Melting point	decomposes around -17.5°C[1]
Related compounds
Other anions	Bromine dioxide Bromine trifluoride Bromine pentafluoride
Other cations	Oxygen difluoride Dichlorine monoxide Chlorine dioxide Iodine dioxide
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

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 dioxide of its halogen neighbor one period higher on the periodic table. The molecule is bent, with C_2v molecular symmetry. The Br-O bond length is 1.85Å and the Br-O-Br bond angle is 112°.^[2][3] A related diatomic molecule bromine monoxide (CAS#15656-19-6 ).

Reactions

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 + HgO → HgBr₂·2H₂O + 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]

References

1. 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. 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. Wiberg, Egon (2001). Wiberg, Nils, ed. Inorganic chemistry (1st ed.). San Diego, Calif.: Academic Press. p. 464. ISBN 9780123526519.