Regioisomeric Switching via Thermal Rearrangement: Toward Safer High-Performance Energetic Materials

High-energy density materials (HEDMs) demand precise structural and energetic control to achieve optimal detonation performance, thermal stability, and insensitivity. Now we report a thermally induced rearrangement in the cine-substitution of 1,3,4-trinitropyrazole with 5-aminotetrazole, resulting in two regioisomeric pyrazole–tetrazole frameworks. At room temperature, nucleophilic substitution at the more reactive tetrazole N1-position gave the kinetic product, 1-(3,4-dinitro-1 H -pyrazol-5-yl)-1 H -tetrazol-5-amine ( 1 ), which undergoes thermal rearrangement to form a C5-NH-linked thermodynamic isomer, N -(3,4-dinitro-1 H -pyrazol-5-yl)-2 H -tetrazol-5-amine ( 2 ) upon heating via a Dimroth-like rearrangement. To enhance performance and safety, compound 2 was converted into energetic salts, with the hydroxylammonium ( 2b, Dv: 9412 m/s) and hydrazinium salts ( 2c, Dv: 9441 m/s) exhibiting superior detonation velocities, superior to HMX. Meanwhile, nitration of the kinetic product yielded N -(1-(3,4-dinitro-1 H -pyrazol-5-yl)-1 H -tetrazol-5-yl)nitramide ( 3 ), which demonstrated the highest detonation velocity (Dv: 9451 m/s), exceeding HMX, while its energetic salts further improve stability with optimized performance. Additionally, carbonyl azide functionalization of 1 resulted in (3,4-dinitro-1 H -pyrazol-5-yl)carbamoyl azide ( 4), which displayed the highest detonation properties (Dv: 8799 m/s; P: 33.2 GPa) among carbonyl azides, comparable to RDX. This study highlights thermally controlled regioisomeric switching as a promising strategy for designing safer, high-performance energetic materials.