Ab Initio and Dft Study of Interaction Between Corannulene and Alkali Cations

Corannulene is an unsaturated hydrocarbon composed of fused rings, one central five-membered ring and five peripheral six-membered rings. Its structure can be considered as a portion of C₆₀. Corannulene is a curved pi surface, but unlike C₆₀, it has two completely different faces: one concave (inside) and one convex (outside). In this work, computational modeling of the binding between alkali metals cations and corannulene has been performed at the DFT and MP2 levels. Different isomers of the corannulene/M⁺ binding have been studied and the transition states interconnecting local minima were located. The alkali cations can be bound to five or six membered ring in both faces. In DFT calculations, the binding to the convex face (outside) is favored relative to the concave face for the three alkali cations as it already has been published [R.C. Dunbar, J. Phys. Chem. A 2002, 106, 9809]. For Li⁺ and Na⁺, MP2 calculations are very similar and show the same trend, but for K⁺ the calculations are quite different and the trend is reversed. According to our results, migration of cations can take place over the convex or the concave pi-face. There are two ways to transform a concave complex in a convex complex: migration across the edge of corannulene and bowl-to-bowl inversion.