CH.(NO2)3

from The Collaborative International Dictionary of English v.0.48

Nitroform \Ni"tro*form\, n. [Nitro- + formyl.] (Chem.)
   A nitro derivative of methane, analogous to chloroform,
   obtained as a colorless oily or crystalline substance,
   {CH.(NO2)3}, quite explosive, and having well-defined acid
   properties.
   [1913 Webster]