2023/06/30 by Tingting Xu, Xudong Hou, Yi Han +3
Chemistry · #Advanced NMR Techniques and Applications #Fullerene Chemistry and Applications #Synthesis and Properties of Aromatic Compounds
paper · doi:10.1002/ange.202304937
openalex publication_date 2023/06/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
Abstract Polycyclic hydrocarbons consisting of two or more directly fused antiaromatic subunits are rare due to their high reactivity. However, it is important to understand how the interactions between the antiaromatic subunits influence the electronic properties of the fused structure. Herein, we present the synthesis of two fused indacene dimer isomers: s ‐indaceno[2,1‐ a ]‐ s ‐indacene ( s ‐ID ) and as ‐indaceno[3,2‐ b ]‐ as ‐indacene ( as ‐ID ), containing two fused antiaromatic s ‐indacene or as ‐indacene units, respectively. Their structures were confirmed by X‐ray crystallographic analysis. 1 H NMR/ESR measurements and DFT calculations revealed that both s ‐ID and as ‐ID have an open‐shell singlet ground state. However, while localized antiaromaticity was observed in s ‐ID , as ‐ID showed weak global aromaticity. Moreover, as ‐ID exhibited a larger diradical character and a smaller singlet‐triplet gap than s ‐ID . All the differences can be attributed to their distinct quinoidal substructures.