Synthesis and development of new energetic molecules is a resource‐intensive process, yielding materials with relatively unpredictable performance properties. Cocrystallization and crystalline solvate formation have been explored as possible routes towards developing new energetic materials that reduce the initial investment required for discovery and performance uncertainty because existing energetic molecules with known properties serve as the constituents. The formation of a hydrogen peroxide (HP) solvate of CL‐20 was previously reported and has a density comparable to that of ϵ‐CL‐20, the densest and most stable polymorph of CL‐20. CL‐20/HP produces a second crystalline form, which was unexpected given the high density of the original CL‐20/HP solvate. Both forms were predicted to have improved detonation performance relative to that of ϵ‐CL‐20. In this work, the detonation velocity of a solvate of CL‐20/HP is measured and compared to that of CL‐20. Using the measured enthalpy of formation, the solvate was predicted to detonate 80 m s−1 faster at a powder density of 1.4 g cm−3; however, experimentally, the solvate detonates 300 m s−1 faster than CL‐20. Thermochemical predictions are also used to show that the solvate detonates 100 m s−1 faster than ϵ‐CL‐20 at the theoretical maximum density, making it the first energetic cocrystal or solvate of ϵ‐CL‐20 predicted to detonate faster than CL‐20 at full density.

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The decomposition mechanisms of 1,3,5-trinitro-1,3,5-triazinane (RDX) have been explored over the past decades, but as of now, a complete picture on these pathways has not yet emerged, as evident from the discrepancies in proposed reaction mechanisms and the critical lack of products and intermediates observed experimentally. This study exploited a surface science machine to investigate the decomposition of solid-phase RDX by energetic electrons at a temperature of 5 K. The products formed during irradiation were monitored online and in situ via infrared and UV–vis spectroscopy, and products subliming in the temperature programmed desorption phase were probed with a reflectron time-of-flight mass spectrometer coupled with soft photoionization at 10.49 eV (ReTOF-MS-PI). Infrared spectroscopy revealed the formation of water (H2O), carbon dioxide (CO2), dinitrogen oxide (N2O), nitrogen monoxide (NO), formaldehyde (H2CO), nitrous acid (HONO), and nitrogen dioxide (NO2). ReTOF-MS-PI identified 38 cyclic and acyclic products arranged into, for example, dinitro, mononitro, mononitroso, nitro–nitroso, and amines species. Among these molecules, 21 products such as N-methylnitrous amide (CH4N2O), 1,3,5-triazinane (C3H9N3), and N-(aminomethyl)­methanediamine (C2H9N3) were detected for the first time in laboratory experiments; mechanisms based on the gas phase and condensed phase calculations were exploited to rationalize the formation of the observed products. The present studies reveal a rich, unprecedented chemistry in the condensed phase decomposition of RDX, which is significantly more complex than the unimolecular gas phase decomposition of RDX, thus leading us closer to an understanding of the decomposition chemistry of nitramine-based explosives.

Understanding of the fundamental mechanisms involved in the decomposition of 1,3,5‐trinitro‐1,3,5‐triazinane (RDX) still represents a major challenge for the energetic materials and physical (organic) chemistry communities mainly because multiple competing dissociation channels are likely involved and previous detection methods of the products are not isomer selective. In this study we exploited a microsecond pulsed infrared laser to decompose thin RDX films at 5 K under mild conditions to limit the fragmentation channels. The subliming decomposition products during the temperature programed desorption phase are detected using isomer selective single photoionization time‐of‐flight mass spectrometry (PI‐ReTOF‐MS). This technique enables us to assign a product signal at m/z=42 to ketene (H2CCO), but not to diazomethane (H2CNN; 42 amu) as speculated previously. Electronic structure calculations support our experimental observations and unravel the decomposition mechanisms of RDX leading eventually to the elusive ketene (H2CCO) via an exotic, four‐membered ring intermediate. This study highlights the necessity to exploit isomer‐selective detection schemes to probe the true decomposition products of nitramine‐based energetic materials.