Substituent effects on heats of formation, group interactions, and detonation properties of polyazidocubanes.

摘要: We have calculated the heats of formation (HOFs) for a series polyazidocubanes by using density functional theory (DFT), Hartree-Fock, and MP2 methods with 6-31G* basis set as well semiempirical methods. The cubane skeleton was chosen reference compound, that is, not broken in process designing isodesmic reactions. There exists group additivity HOF respect to azido group. AM1 method also produced reliable results HOFs title compounds, but MINDO3 did not. relationship between molecular structures discussed. It found increases 330–360 kJ/mol each additional number being added skeleton. distance groups slightly influences values HOFs. interacting energies neighbor are range 2.3∼6.6 kJ/mol, which so small less related substituent numbers. average interaction energy nearest N3 most stable conformer octaazidocubane is 2.29 at B3LYP/6-31G* level. relative stability compounds assessed based on HOFs, gaps frontier orbitals, bond orders CN3 CC bonds. predicted detonation velocity hepta- octa-derivatives over 9 km/s, pressure them ca. 40 GPa or over. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1263–1269,