Ab initio calculations of ten carbon/nitrogen cubanoids
- Los Alamos National Lab., NM (United States)
The results of a uniform set of ab initio quantum-chemical calculations for 10 carbon/nitrogen cubanoids are presented. There are 22 possible C/N cubanoids with formulas (CH)[sub 8[minus]n]N[sub n], where 0 [le] n [le] 8. We give results for one cubanoid for each value of n; for n = 4 both the T[sub d] and C[sub 4v] structures are discussed. The geometries were optimized on the RHF/6-31G*//RHF/6-31G* energy hypersurfaces, and the stationary points so obtained were characterized by vibrational analyses. The effect of electron correlation on the energies of these structures is examined via MP2/6-31G*//RHF/6-31G* theory. All 10 structures are predicted to be stable molecules, and the vibrational analyses indicate that their geometries are well-defined by the RHF/6-31G*//energy hypersurfaces. Heats of formation are predicted via appropriate isodesmic reactions. All the structures are found to have large positive [delta]H[sub f]'s. Perhaps the most interesting result obtained is that the high-energy content of the nitrogen-rich cubanoids is not primarily due to bond strain, but rather to the high-energy content of the NN single bond. Comparisons of the ab initio [delta]H[sub f] values with semiempirical AM1, PM3, and MNDO predictions are made. If they can be synthesized and have reasonable kinetic stability, the C/N cubanoids containing four or more nitrogen atoms are likely to be important energetic materials. A brief discussion is given of the potential of these materials as propellants and explosives. 22 refs., 5 figs., 4 tabs.
- OSTI ID:
- 6300997
- Journal Information:
- Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 115:7; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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360600* -- Other Materials
360602 -- Other Materials-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
CALCULATION METHODS
CARBON COMPOUNDS
ENERGY LEVELS
EXCITED STATES
EXPLOSIVES
MECHANICS
MOLECULAR STRUCTURE
NITROGEN COMPOUNDS
ORGANIC COMPOUNDS
PROPELLANTS
QUANTUM MECHANICS
VIBRATIONAL STATES