Identification of liquid-phase decomposition species and reactions for guanidinium azotetrazolate

• Guanidinium azotetrazolate (GzT) is a high-nitrogen energetic material.
• FTIR spectroscopy and ToFMS spectrometry were used for species identification.
• Quantum mechanics was used to identify transition states and decomposition pathways.
• Important reactions in the GzT liquid-phase decomposition process were identified.
• Initiation of decomposition occurs via ring opening, releasing N2.

The objective of this work is to analyze the decomposition of guanidinium azotetrazolate (GzT) in the liquid phase by using a combined experimental and computational approach. The experimental part involves the use of Fourier transform infrared (FTIR) spectroscopy to acquire the spectral transmittance of the evolved gas-phase species from rapid thermolysis, as well as to acquire spectral transmittance of the condensate and residue formed from the decomposition. Time-of-flight mass spectrometry (ToFMS) is also used to acquire mass spectra of the evolved gas-phase species. Sub-milligram samples of GzT were heated at rates of about 2000 K/s to a set temperature (553–573 K) where decomposition occurred under isothermal conditions. N2, NH3, HCN, guanidine and melamine were identified as products of decomposition. The computational approach is based on using quantum mechanics for confirming the identity of the species observed in experiments and for identifying elementary chemical reactions that formed these species. In these ab initio techniques, various levels of theory and basis sets were used. Based on the calculated enthalpy and free energy values of various molecular structures, important reaction pathways were identified. Initiation of decomposition of GzT occurs via ring opening to release N2.