Density functional theory calculations for simple prototypes of perfluorocarbons: neutral and anionic c-C4F8 and 2-C4F8

作者：Choi Heechol; Park Young Choon; Lee Yoon Sup; Baeck Kyoung Koo^*

来源：Journal of Fluorine Chemistry, 2013, 146: 46-52.

DOI：10.1016/j.jfluchem.2013.01.002

• Perfluorocarbons
• Octafluorocyclobutane
• Perfluoro-2-butene
• Density-functional-theory
• Electron Affinity
• Trans-to-cis isomerization

In order to find a density functional theory (DFT) method appropriate to perfluorocarbon molecules (PFCs), the properties of three isomeric forms of C4F8 were calculated, with special emphasis on the ring-puckering angle (delta), electron affinity (EA), and the inversion barriers to the ring-puckering (Delta E-RP) of c-C4F80,- and the trans-to-cis isomerization (Delta E-iso) of 2-C4F80,-. It was shown that reliable calculations of the EAs of the PFCs require that at least one set off functions be added to the split valence-shell type and diffuse basis functions. Our analysis of the calculated values recommends the omega B97X-D/aVTZ method for future studies of other PFC systems. Examination of the trans-to-cis isomerization of the neutral 2-C4F8 and anionic 2-C4F8- systems revealed that the transition state of the neutral form (TSiso) is symmetric but that its anionic counterpart (TSiso-) is asymmetric in both geometry and charge distribution. This asymmetry corresponds to a kind of electronic charge flow from one side of 2-C4F8- to the other. The reason for the lower energy barrier of the isomerization of the anion than that of the neutral form is also discussed.

• 出版日期2013-2