Computational characterization of 2, 4, 6, 8, 10, 12, 13-heptaazatetracyclo [5.5.1.0 3,11 .0 5,9 ]tridecanes as potentia
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ORIGINAL RESEARCH
Computational characterization of 2, 4, 6, 8, 10, 12, 13-heptaazatetracyclo [5.5.1.03,11.05,9]tridecanes as potential energetic compounds Jian-ying Zhang • Fang Wang • Xue-dong Gong
Received: 9 December 2012 / Accepted: 29 January 2013 Ó Springer Science+Business Media New York 2013
Abstract The characters of high density and high heat of formation of cage molecules have attracted a lot of investigations as potential energetic materials. Several such compounds have been synthesized, e.g., octanitrocubane, hexanitrohexaazaisowurzitane (CL-20), and 4-trinitroethyl2, 6, 8, 10, 12-pentanitrohexaazaisowurtzitane(TNE-CL20). In the present study, a new cage compound, namely 2, 4, 6, 8, 10, 12, 13-heptaazatetracyclo [5.5.1.03,11.05,9] tridecane (HATT), was proposed. Density functional theory has been employed to study the geometric and electronic structures for a series of nitro derivatives of HATT at the B3LYP/631G(d,p) level. Thermodynamic properties derived on the basis of statistical thermodynamic principles are linearly correlated with the numbers of nitro group as well as the temperature. Detonation performance was evaluated based on the calculated densities and heats of formation. It is found that some title compounds have high densities of ca. 1.9 g cm-3, detonation velocities over 9.0 km s-1, and detonation pressures of about 40.0 GPa and may be novel potential candidates of high energy density compounds (HEDCs). Thermal stability and pyrolysis mechanism of the nitro HATTs were investigated by calculating the bond dissociation energies (BDE). In conjunction with the detonation performance and thermal stability, HATTs with no less than five nitro groups are recommended as the preferred candidates of HEDCs. These results provide basic information for the further studies of cage compounds. Keywords Cage DFT Detonation performance Bond dissociation energy Stability J. Zhang F. Wang X. Gong (&) School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, People’s Republic of China e-mail: [email protected]
Introduction High nitrogen heterocyclic cage compounds have attracted considerable interest as high energy density compounds (HEDCs) [1–15]. This class of novel high-nitrogen compounds form a unique class of energetic materials possessing high positive heat of formation (HOF), good detonation performance, and high thermal stability that result in numerous applications, such as solid fuels in micropropulsion systems, gas generators, and smoke-free pyrotechnic fuels [16]. Most of the energy comes either from oxidation of the carbon backbone, as traditionally found in common explosives, such as RDX (cyclotrimethylenetrinitramine) and HMX (cyclotetramethylenetetrainitramine), or from the strain energy in the cage system. Some heterocyclic cage compounds were synthesized recently and exhibited high performance in terms of explosive velocity and pressure. CL-20 [2, 4, 6, 8, 10, 12-hexanitrohexaazaisowurtzitane] is such a new cage compound that is
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