Computational Study of 13C NMR Chemical Shift Anisotropy Patterns in C20H10 and [C20H10]4-. Insights into Their Variation upon Planarization and Formation of Concentric Aromatic Species in the Smaller Isolated-Pentagon Structural Motif.

摘要: Corannulene, C20H10, exhibits a concave surface in the ground state that is able to experience bowl-to-bowl inversion through planar conformation. Such structure smaller example resembling an isolated-pentagon motif, as relevant fragment fullerene chemistry. Here, we explored differences between bowl and conformations involving both energetic 13C NMR properties, for neutral tetraanionic species by using density functional theory (DFT) methods. This allows us understand variation of chemical environment at carbon atoms upon planarization this representive motif. Our results reveal shift comes about from different main components shielding tensor, according relative position (i.e., rim, hub, protonated), which more hub protonated sites, contrast rim remaining almost unshifted. Interestingly, ...