Table 1: Comparison of the strainless gas-phase heat of formation, destabilization energy, and gas-phase heat of formation of CL-20, ONC, and other relevant compounds of interest.

CompoundStrainless heat of formation
Heat of formation
Destabilization energy or CRSE (kJ/mol)Destabilization energy per C + N present in the ring or the cage (kJ/mol)

Cyclobutane −82.529.7112.228.1
HAIW I 325.3 306.6 −18.7−1.6
HAIW II 325.3 301.7 −23.6−2.0
HAIW III 325.3 323.1 −2.2−0.2
HAIW IV 325.3 290.5 −34.8−2.9
Isowurtzitane−171.5−63.5 108.0 9.0
CL-20 (HNIW I)240.0558.8318.826.6
CL-20 (HNIW II)240.0554.4314.426.2
CL-20 (HNIW III)240.0571.6331.627.6
CL-20 (HNIW IV)240.0548.0308.025.7
Cubane −63.6622.2685.885.7
Octanitrocubane −405.0687.51,092.5136.6

The values in parentheses for octanitrocubane are the heat of formation value calculated by Zhang and Xiao [8] and values calculated using this heat of formation.
Other values in parentheses are those reported in, or calculated using, those referenced in the NIST Chemistry WebBook ( or in the CRC’s Standard Thermodynamic Properties of Chemical Substances.
HAIW refers to 2,4,6,8,10,12-hexaazaisowurtzitane.