CNO2Br3

from The Collaborative International Dictionary of English v.0.48

Brompicrin \Brom*pi"crin\, n. [G. brompikrin; brom bromine +
   pikrins[aum]ure picric acid.] (Chem.)
   A pungent colorless explosive liquid, {CNO2Br3}, analogous to
   and resembling chlorpicrin. [Spelt also {brompikrin}.]
   [1913 Webster] Brompton's cocktail
   Brompton mixture
   Brompton's mixture