A novel
degradation pathway of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane
(CL-20) was identified using computational and experimental methods.
Density functional theory (DFT) calculations were employed to obtain
its unimolecular degradation pathway, and ultrahigh-performance liquid
chromatography–high-resolution mass spectrometry, thermogravimetry–Fourier
transform infrared spectrometry, thermogravimetry, and differential
scanning calorimetric experimental data were used to validate the
computationally deduced degradation pathways. Based on the indications
from computational and experimental results, the cleavage of the strained
fragment from CL-20 was identified instead of NO2 or HONO
elimination as in conventional high energy materials. This fragmentation
results in the formation of two energetic species, dinitrodihydropyrazine
and dinitroformimidamide, which makes CL-20 one of the most powerful
energetic materials. This novel degradation pathway of CL-20 will
be useful in understanding the decomposition of cage molecules, design
of new practical energetic molecules, and development/improvement
of thermokinetic codes used for energetic property calculations.