Trihydride tetrazine
From Halopedia, the Halo wiki
Trihydride tetrazine, H5C2N4, is a chemical compound used in UNSC emergency thrusters. When mixed with hydrogen peroxide, an explosive force is produced that is large enough to radically alter the course of UNSC ships.[1]
The same compound is used in Pelicans to achieve "chemical thrust" in space flight.[2]