Shear induced weakening of the hydrogen bonding lattice of the energetic material 5,5′-Hydrazinebistetrazole at high-pressure

Abstract

5,5'-Hydrazinebistetrazole (HBTA) has been studied by in-situ x-ray diffraction and vibrational spectroscopy to pressures near 25 GPa at room temperature. Analysis of the x-ray diffraction pattern of HBTA collected at ambient pressure and temperature revealed a monoclinic structure consistent with that previously reported. Under compression, the x-ray diffraction reveals little evidence of a phase transition over the pressure range studied. Slight anisotropy in response to compression was noted and the β angle decreased moderately, suggesting geometry modifications occur in the hydrogen bonding lattice and between neighboring HBTA molecules as a result of compression along the c axis. Blue shifts in the Infrared active N-H stretching modes were observed, implying a weakening of the hydrogen bond with compression. The weakening of the hydrogen bonding lattice with pressure may lead to an increase in the bending angle of the C-N=N-C bridge between the tetrazole rings and an increased overlap between the π-bonding orbitals. The Raman spectra showed a number of modes associated with HNNH motions of the bridge become more prominent in the spectra under compression. Additionally, the possibility that the increased bend in the angle of the C-N=N-C bridge results from a shearing deformation is discussed.

Phase transition and trigger mechanism of initial reaction under pressure for benzofuroxan energetic materials: Raman spectroscopy and first‐principle calculations

“…Therefore, it is necessary to understand the initial molecular dynamic response of energetic materials to pressure. [ 5 ]…”

The role of H-bond in the high-pressure chemistry of model molecules

“…However, the strengthening of hydrogen bonds along multiple directions can also lead to a sort of freezing of intermolecular configurations thus kinetically hindering structural or chemical transformation. This occurrence is rather common in energetic crystals where the stability at high pressure is often related to hydrogen bonding [20][21][22][23][24], an important issue in view of understanding the mechanisms ruling the insensitivity of explosives [25,26].…”