Computational studies on C_(24)H_(8),C_(28)H_(12),andC_(32)H_(16)isomers in which the cubane,pentaprismane, or hexaprismane cages are linked by four CC bonds

摘要

Quantum-chemical calculations on C24H8, C28H12, and C32H16 isomers in which the cubane, pentapris-mane, or hexaprismane cages are linked by four C=C bonds have been performed using density func-tional theory (DFT) method. The geometric structures, energies, vibrational frequencies, and verticalionization energy as well as vertical electron affinity of various isomers have been obtained at theB3LYP/6-31G~(**) level of theory. Meanwhile, the present paper has also computed the enthalpies of forma-tion for different isomers so as to evaluate their stability from a thermodynamic point of view. Thereexists two different isomers for C_(28)H_(12)and C_(32)H_(16)in which the prismane (pentaprismane or hexapris-mane) cages are parallel or perpendicular to each other. It has been concluded that the isomer in whichthe prismane (pentaprismane or hexaprismane) cages are perpendicular is more stable and has relativelysmaller heat of formation.