Year: 2026
Type: preprint
Abstract: The coexistence of 2D π-aromaticity and 3D σ-aromaticity within a single edge-fused molecule remains an open question, as the two aromatic subsystems are often assumed to be electronically incompatible. Here we fuse benzene, C 7 H 7 + and C 7 H 7 – onto the pentagonal-bipyramidal B 7 H 5 /C 2 B 5 H 5 fragment and systematically vary the fusion-edge composition (B–B, B–C, C–C), evaluating the 2D ring with GIMIC bond currents, NICS, ISE and EDDB. The 3D cage aromaticity remains essentially intact in aromatic cases, whereas the fate of the 2D ring depends strongly on the ring type and the fusion edge. Benzene fusion gives only weakly aromatic 2D rings, while C7H7 + fused through boron-rich edges develops a desymmetrized through-edge current path and sustains strong diatropic circuits up to 13.2 nA/T, restoring magnetic communication between the 2D ring and the 3D cage. Adding two electrons instead produces local paratropic circuits on the 2D rings via a HOMO-to-LUMO rotational transition. Throughout these systems the four descriptors diverge within both aromatic and antiaromatic series.
Source: ChemRxiv
Authors: Guo Yu, Zhanchao Meng, Guangxin Liang
Institution: ShanghaiTech University
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Awards: 若干化学相关多环西松烷类天然产物的集合式合成研究, G4985277076
OpenAlex ID: W7216427668