Solvate of 2,4,6,8,10,12‐Hexanitro‐2,4,6,8,10,12‐Hexaazaisowurtzitane (CL‐20) with both N 2 O 4 and Stable NO 2 Free Radical

A new solvate of a powerful explosive 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane (CL‐20) and liquid oxidizer N 2 O 4 has been synthesized. When stored at room temperature, the white crystals turn yellowish brown, which indicates partial dissociation of N 2 O 4 with the formation of a stable NO 2 free radical, which is confirmed by ESR spectroscopy. The resulting solvate was analyzed by powder X‐ray diffraction, IR‐spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The vapor pressure of NO 2 above the solvate crystals is similar to the pressure above common hydrates. The presence of the NO 2 radical does not affect the thermal stability of CL‐20. However, under closed conditions, NO 2 increases the rate of the autocatalytic decomposition reaction. The kinetics of this reaction at the surface temperature determine the burning rate of the solvate. The novel solvate has a high density (1.98 g cm −3 ), a high predicted detonation velocity and pressure, and sensitivity to impact slightly higher to that of ϵ‐CL‐20.