Bonding character, electronic properties, and electronic transitions of perfluorocubane as a small electron acceptor

Abstract

Perfluorocubane is a fluorinated analogue of a polyhedral hydrocarbon observed recently in experiment (M. Sugiyama, M. Akiyama, Y. Yonezawa, K. Komaguchi, M. Higashi, K. Nozaki and T. Okazoe, Electron in a cube: Synthesis and characterization of perfluorocubane as an electron acceptor, Science, 2022, 377, 756–759). Inspired by its unique structure and electronic properties, we systematically explored its chemical stabilities, bonding character, electronic properties, and electronic transitions using density functional theory calculations. Analysis of the binding energies and Mayer bond orders reveals that the C₈F₈ molecule has high chemical stability with a special electronic structure, and the addition of an extra electron to the neutral molecule may generate a radical anion with a hosted electron inside the cubane frame. The induced ring currents under an external magnetic field reveal that perfluorocubane exhibits an overall small diamagnetic current supported by anisotropy of the current-induced density (ACID) and gauge-including magnetically induced currents (GIMIC). AdNDP analysis indicates that the localized two-center two-electron (2c–2e) σ-bonds are responsible for structural stabilization of the molecule. Further study into the electronic excitations shows that the main electronic transitions of perfluorocubane come from the surface of the cubic frame to its inner structure. Consequently, perfluorocubane can be recognized as a small electron acceptor material due to its special electron-carrying capacity, which will promote further applications of novel conducting and semiconducting materials.