High energy and moderate sensitivity are the two most important demands for modern energetic materials. The powerful CL-20 and its previously obtained derivatives do not meet safety requirements. To reach the desired goal of high-performance polycyclic cage multi-nitramine structures with reduced sensitivity, a novel family of energetic compounds was designed and synthesized by the incorporation of an alkylnitramine moiety into the pentanitro hexaazaisowurtzitane backbone. All obtained compounds were fully characterized by high-resolution mass spectrometry, IR and multinuclear NMR (¹H, ¹³C{¹H}, ¹⁴N, and ¹⁵N{¹H}) spectroscopy, and some of them with single-crystal X-ray diffraction. For the target substances, the enthalpies of formation were determined experimentally by combustion calorimetry. Thermal stability measurements and safety testing were carried out. Their energetic potential as components of rocket propellants was studied using high-temperature chemical equilibrium thermodynamic calculations. The most attractive of the new materials, N-methyl-N-[(2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexaazaisowurtzitan-4-yl)methyl]nitramide and N,N′-bis[(2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexaazaisowurtzitan-4-yl)methyl]nitramide, exhibit high density (1.86–1.92 g cm⁻³), heat resistance (decomposition onset at about 223 °C) and enthalpy of formation (up to about 10³ kJ kg⁻¹). Moreover, they are the most insensitive among energetic hexaazaisowurtzitane derivatives known and are up to 2/4 times safer against impact/friction than CL-20. The combination of admirable properties makes these materials promising for use in high-energy condensed systems. The target compounds are highly effective energetic components for metal-free rocket propellants, providing, at moderate contents, specific impulse values 6.5–8 s higher than similar formulations based on CL-20.

New energetic materials based onN,N′-methylene bridged polyfunctionalized cage compounds are reported in which derivatives of bis(polynitrohexaazaisowurtzitanyl)methane have both a higher enthalpy of formation and a lower friction sensitivity than CL-20.

To design high-energy-density materials of a new level, it is necessary to develop methods for the functionalization of energetic scaffolds, which will make it possible to tune their physicochemical and energetic properties. For this reason, we have elaborated an approach to synthesize a new series of energetic cage compounds with advanced properties by introducing the N-cyano group into the polynitro hexaazaisowurtzitane framework. The structures of the obtained substances were fully characterized with a combination of methods, including multinuclear (¹H, ¹³C{¹H}, ¹⁴N, and ¹⁵N{¹H}) NMR and IR spectroscopy, high-resolution mass spectrometry, X-ray diffraction analysis, electron microscopy and quantum chemical calculations. For the resulting compounds, the thermal stability and safety tests were carried out, calorimetric and pycnometric measurements were performed, as well as the energetic potential was determined by high-temperature chemical equilibrium thermodynamic calculations. The new cyano derivatives have an acceptable density (up to 1.92 g cm^–3) and a high enthalpy of formation (up to 2 MJ kg^–1), which is 2 times that of the benchmark CL-20. The resistance of the target compounds to friction (up to 220 N) is the highest compared to CL-20 and its known analogues. 4,10-Dicyano-2,6,8,12-tetranitro-2,4,6,8,10,12-hexaazaisowurtzitane of the new series is the most thermally stable (T_dec 238 ^oC) among the known energetic polynitro hexaazaisowurtzitanes and is the first derivative of this family to surpass CL-20 in heat resistance. Moreover, the specific impulse for the novel materials showed an improvement of 6.5–13 s over CL-20.