Dual-Platform Design of Tetrazole Energetics: Fused Heterocycles and Oxadiazole–Tetrazole Linkages with Oxygen-Rich Substituents

A molecular design strategy integrating nitrogen-rich fused-ring or 1,3,4-oxadiazole frameworks with dinitromethyl-substituted tetrazoles was developed to enhance the energetic performance. The resulting compounds combine high detonation parameters with favorable thermal stability (Td = 127–161 °C) and mechanical insensitivity (IS = 8–30 J, FS = 120–240 N). Nitration of the 1,3,4-oxadiazole moiety in compound 10 yields outstanding performance (Dv = 8613 m·s–1, P = 29.0 GPa, and ρ = 1.81 g·cm–3). Single-crystal X-ray analysis shows the dinitromethyl group adopts a near-perpendicular orientation to the tetrazole, reducing π–π stacking but improving oxygen balance. In fused-ring systems, inner-salt formation disrupts conjugation and induces a twisted conformation, enhancing intramolecular electrostatic interactions and thermal stability. Importantly, introduction of a –CH2COCH3 substituent via chloroacetone─which is further converted to a dinitromethyl motif under nitration─facilitates successful nitramination of the oxadiazole amino group. This substituent lowers the LUMO, shifts the preferred protonation site away from the amino nitrogen, preserves the amino lone pair for attack by NO2+, and, together with the nitroform fragment, improves charge delocalization and oxygen balance. Collectively, these features produce nitramino/dinitro-functionalized tetrazoles with enhanced reactivity and energetic metrics, demonstrating that coupling oxygen-rich explosophores with tunable nitrogen-rich backbones is an effective approach to high-energy, low-sensitivity energetic materials.