Selenium oxybromide explained

Selenium oxybromide (SeOBr₂) is a selenium oxohalide chemical compound.

Preparation

Selenium oxybromide can be prepared through the reaction of selenium dioxide and selenium tetrabromide. Selenium and selenium dioxide are reacted with bromine to form selenium monobromide and selenium tetrabromide. Dissolving the selenium dioxide in the tetrabromide will produce the oxybromide.^[1]

2 Se + Br₂ → Se₂Br₂

Se₂Br₂ + 3 Br₂ → 2 SeBr₄

SeBr₄ + SeO₂ → 2 SeOBr₂

Structure

Evidence from infrared and polarized Raman spectroscopy suggests that selenium oxybromide adopts a pyramidal molecular geometry with C_s symmetry,^[2] like other chalcogen(IV) oxohalides such as thionyl bromide and selenium oxydichloride .

Properties

Selenium oxybromide is a reddish-brown solid with a low melting point (41.6 °C) and chemical properties similar to selenium oxychloride. It boils at 220 °C and decomposes near the boiling point, making distillation an ineffective purification method. Its electrical conductivity in the liquid state just above the melting temperature is 6×10⁻⁵ S/m. SeOBr₂ is hydrolyzed by water to form H₂SeO₃ and HBr.

SeOBr₂ is highly reactive, with most reactions taking place in the liquid state. Selenium will dissolve in it, forming Se₂Br₂. Iron, copper, gold, platinum, and zinc are all attacked by SeOBr₂.

Notes and References

1. Lenher. Victor. Journal of the American Chemical Society. 1 August 1922. 44. 8. 1668–1673. 10.1021/ja01429a008. Selenium oxybromide.
2. MSc . Wilson . William W. . 1972 . Vibrational spectroscopic studies of some simple and mixed selenium(iv) oxy-halides and pseudohalides . University of British Columbia . 10.14288/1.0061859 .