Unimolecular Decomposition of 5-Aminotetrazole and its Tautomer 5-Iminotetrazole: New Insight from Isopotential Searching

Abstract

Aminotetrazole compounds have become attractive ingredients in gas generating compositions, solid rocket propellants, and green pyrotechnics. Therefore, a fundamental understanding of their thermal decomposition mechanisms and thermodynamics is of great interest. In this study, the specular reflection isopotential searching method was used to investigate the unimolecular decomposition mechanisms of 5-iminotetrazole (5-ITZ), 1H-5-aminotetrazole (1H-5-ATZ), and 2H-5-aminotetrazole (2H-5-ATZ). Subsequent thermochemical analysis of the unimolecular decomposition pathways was performed at the CCSD(T)/aug-cc-pVTZ//B3LYP/6-311++G(3df,3pd) level of theory. Based upon the relative reaction barriers predicted in this study, the initial gaseous products of 5-ITZ unimolecular decomposition are HN 3 and NH 2 CN (calculated activation barrier equal to 199.5 kJ/mol). On the other hand, the initial gaseous products of 1H-5-ATZ and 2H-5-ATZ unimolecular decomposition are predicted to be N 2 and metastable CH 3 N 3 (calculated activation barriers equal to 169.2 and 153.7 kJ/mol, respectively). These predicted unimolecular decomposition products and activation barriers are in excellent agreement with thermal decomposition experiments performed by Lesnikovich et al.

Environmental Fate and Transport of Energetic Materials

“…As with other previously published data, the pathways and energetics of the Kiselev et al work were very much in alignment with experimental results [10][11] . It is also in alignment with results of the IPS-based unimolecular decomposition study [6] , with one exception. This exception is the IPS-generated pathway shown in Figure 3 representing the 1H-5-ATZ unimolecular decomposition leading to HN 3 and NHCNH products.…”

“…A thorough description of all 7 schemes is not feasible here, and the interested reader is directed to our recent manuscript on the topic [6] . It is interesting to note however, that additional work on the decomposition of these compounds has been published since the release of this material [9] .…”

Synthesis, structural investigation and thermal properties of a novel manganese complex Mn2(DAT)2Cl4(H2O)4 (DAT=1,5-diaminotetrazole)

“…Kissinger's and Ozawa-Doyle's method were applied to study the kinetic parameters of one endothermic peak and the two main exothermic peaks of Mn 2 (DAT) 2 …”

“…Tetrazole derivatives have attracted much attention in the field of heterocyclic compounds due to their varied structures and properties. 5-Substituted tetrazoles, such as 5-amino-tetrazole [1][2][3][4][5][6][7], 5-nitramino-tetrazole [8][9][10][11][12][13], 5-nitro-tetrazole [14][15][16][17][18][19][20][21] and 5-azido-tetrazole [22][23][24][25] can form a series of metal salts or coordination compounds with transition metals and alkaline metals as its weakly acidic. Most of these compounds have extreme properties and have been widely used in the area of gas-generation and energetic materials because of their high nitrogen content and positive enthalpies of formation.…”

“…Manganese exhibits a good ability when coordinating with different kinds of ligand, and is more environmental friendly compared with the toxic heavy metal element as lead and mercury. Therefore, in this work we synthesized and characterized the novel manganese complex Mn 2 (DAT) 2 4 exhibits good energetic properties and the bridge structure gives the complex high thermal stability. In this paper the synthesis, crystal structure of Mn 2 (DAT) 2 Cl 4 (H 2 O) 4 and a proposed thermal decomposition mechanism, from the DSC, TGA-DTG and FT-IR analysis results, is presented.…”