Nitration products of 5-amino-1H-tetrazole and methyl-5-amino-1H-tetrazoles - Structures and properties of promising energetic materials

The nitration of 5-amino-1H-tetrazole (1). 5-amino-1-methyl-1H-tetrazole (3), and 5-amino-2-methyl-2H-tetrazole (4) with HNO3 (100%) was undertaken, and the corresponding products 5-(nitrimino)-1H-tetrazole (2) 1-methyl-5-(nitrimino)-1H-tetrazole (5), and 2-methyl-5-(nitramino)-2H-tetrazole (6) were characterized comprehensively using vibrational (IR and Raman) spectroscopy, multinuclear (H-1, C-13, N-14, and N-15) NMR spectroscopy, mass spectrometry, and elemental analysis. The molecular structures in the crystalline state were determined by single-crystal X-ray diffraction. The thermodynamic properties and thermal behavior were investigated by using differential scanning calorimetry (DSC), and the heats of formation were determined by bomb calorimetric measurements. Compounds 2, 5, and 6 were all found to be endothermic compounds. The thermal decompositions were investigated by gas-phase IR spectroscopy as well as DSC experiments. The heats of explosion, the detonation pressures, and velocities were calculated with the software EXPLO5, whereby the calculated values are similar to those of common explosives such as TNT and RDX. In addition, the sensitivities were tested by BAM methods (drophammer and friction) and correlated to the calculated electrostatic potentials. ne explosion performance of 5 was investigated by Koenen steel sleeve test, whereby a higher explosion power compared to RDX was reached. Finally, the long-term stabilities at higher temperatures were tested by thermal safety calorimetry (FlexyTSC). X-Ray crystallography of monoclinic 2 and 6, and orthorhombic 5 was performed.