Stability and Energetics of Metastable Molecules: Tetraazatetrahedrane (N4),Hexaazabenzene (N6) and Octaazacubane (N8)

摘要

By use of ab initio self-consistent field (SCF), coupled-cluster, and -many-bodyperturbation theory (MBPT) methods, the potential nitrogen molecules, tetrahedral N4 and octahedral N8, are found to be metastable, corresponding to local minima on their respective potential energy surfaces. Barriers to unimolecular dissociation appear to be large enough that the unknown molecules could be formed. Three additional N4 Structures (Cs, C2v, and D2h) are also found. Vibrational frequencies are computed at the MBPT(2) level to aid in the identification of these unknown molecules. Similar analysis of the N6 analogue of benzene demonstrates, unambiguously, that even though hexaazabenzene is a local minimum at the SCF level, at the correlated level it is a second-order saddle point of the N6 surface. Metastable, ab initio, MBPT, tetrahedral.