Looking for high-energy density compounds among hexaazaadamantane derivatives with - CN, - NC, and - ONO2 groups

摘要

Density functional theory (DFT) was employed to evaluate the heats of formation (HOFs) for hexaazaadamantane (HAA) derivatives with -CN, -NC, and -ONO2 groups, respectively. This was done by designing isodesmic reactions at the B3LYP/6-31G* level of theory, where the HAA cage skeletons were kept unbroken to produce more accurate results, and all HOFs for the required reference compounds, NH2CN, NH2NC, NH2ONO2, and (CH2NH)(3),were derived from the G(3) theory calculation based on the atomization energies. The calculation results show that the HOFs of HAA derivatives are mainly affected by the number and the position of substituent groups, all the obtained HOFs are positive, and the -NC derivatives have the most HOFs among the three types of derivatives with the same number of substituent groups. The detonation velocity (D) and detonation pressure (P) were obtained from the empirical Kamlet-Jacobs equations. All the -NC and -CN derivatives of HAA have lower densities (rho), heats of explosion (Q), D, and P. However, these properties of -ONO2 derivatives are rather high and vary with the number of -ONO2 groups. Considering the easiness for synthesis and relative stability, 2,4,6,8-hexaazaadamantanenitrate is finally recommended as a potential candidate of a high-energy density compound (HEDC).