Interplay of Aromaticity and Coulomb Repulsion in the Electronic Structure of a Dimeric Pentafulvalene Upon Multi-Electron Uptake
4 affiliations
- 1Institute for Integrated Cell-Material Sciences (WPI-iCeMS, Institute for Advanced Study, Kyoto University, Yoshida, Sakyo-ku, Kyoto, Japan, 606-8501
- 2Department of Chemistry
- 3State University of New York
- 4Graduate School of Engineering, Kyoto University, Yoshida, Sakyo-ku, Kyoto, Japan, 606-8501
Abstract
Multielectron reduction of finite one-dimensional (1D) π-conjugated hydrocarbons remains poorly understood because such frameworks are usually unstable due to charge accumulation in the absence of electron-withdrawing substituents. Here, we investigate the reduction of dibenzopentafulvalene dimers ([2]DBFs), a rare class of quasi-1D conjugated hydrocarbons that exhibit unusual stability toward multi-electron reduction and contain four indenylidene subunits that can each become aromatic upon reduction, raising the question of where the excess electrons reside. Chemical reduction of [2]DBFs with alkali metal-based reductants afforded dianionic and tetraanionic species, which were characterized by electronic absorption spectroscopy, NMR spectroscopy, single-crystal X-ray diffraction, and complementary quantum chemical calculations. The dianions accommodate excess negative charge at the outer indenylidene subunits, where Coulomb repulsion is minimized by charge separation while gaining 10π Hückel aromaticity. In contrast, upon four-electron reduction, all four indenylidene subunits become aromatic, and the excess charge becomes more broadly distributed and can extend to the end-capping phenyl groups even at the expense of the aromatic character of the end-capping benzene rings. The solid-state structures further reveal that the observed charge distributions are strongly influenced by the spatial arrangement of counter cations. These results identify local aromatization, Coulomb repulsion, and countercation position as competing factors that determine where electrons reside in multiply charged finite 1D π-conjugated hydrocarbons.
Related
- Aromaticity in Polycyclic Aromatic Hydrocarbons (PAHs): A Comparative Analysis Using Magnetic, Geometric, and Electronic Criteria
- Electrochemical Metastability of Au–Pd Alloy Nanoparticles: Interplay between Alloying, Surface Structure, and Halide-Induced Dissolution
- Poly(pentafulvalene)s: One-Dimensional Conjugated Hydrocarbons toward Stable and Narrow-Bandgap Polyenes
- Structure–Performance Interplay and Mechanical Degradation Modes in Lithium Cobalt Oxide Cathodes: Implications for Flexible Lithium-Ion Battery Design
- VIBE-QC: an open-source, general-purpose electronic-structure code for molecules and solids developed with generative AI
BibTeX
@misc{wang2026interplay,
title = {{Interplay of Aromaticity and Coulomb Repulsion in the Electronic Structure of a Dimeric Pentafulvalene Upon Multi-Electron Uptake}},
author = {Zhe Wang and Yikun Zhu and Zheng Wei and Herdya S. Torchon and Shu I. Takagi and Marina A. Petrukhina and Aiko Fukazawa},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15011124/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15011124/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Interplay of Aromaticity and Coulomb Repulsion in the Electronic Structure of a Dimeric Pentafulvalene Upon Multi-Electron Uptake
AU - Zhe Wang
AU - Yikun Zhu
AU - Zheng Wei
AU - Herdya S. Torchon
AU - Shu I. Takagi
AU - Marina A. Petrukhina
AU - Aiko Fukazawa
PY - 2026
DA - 2026/10/27
PB - ChemRxiv
DO - 10.26434/chemrxiv.15011124/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15011124/v1
AB - Multielectron reduction of finite one-dimensional (1D) π-conjugated hydrocarbons remains poorly understood because such frameworks are usually unstable due to charge accumulation in the absence of electron-withdrawing substituents. Here, we investigate the reduction of dibenzopentafulvalene dimers ([2]DBFs), a rare class of quasi-1D conjugated hydrocarbons that exhibit unusual stability toward multi-electron reduction and contain four indenylidene subunits that can each become aromatic upon reduction, raising the question of where the excess electrons reside. Chemical reduction of [2]DBFs with alkali metal-based reductants afforded dianionic and tetraanionic species, which were characterized by electronic absorption spectroscopy, NMR spectroscopy, single-crystal X-ray diffraction, and complementary quantum chemical calculations. The dianions accommodate excess negative charge at the outer indenylidene subunits, where Coulomb repulsion is minimized by charge separation while gaining 10π Hückel aromaticity. In contrast, upon four-electron reduction, all four indenylidene subunits become aromatic, and the excess charge becomes more broadly distributed and can extend to the end-capping phenyl groups even at the expense of the aromatic character of the end-capping benzene rings. The solid-state structures further reveal that the observed charge distributions are strongly influenced by the spatial arrangement of counter cations. These results identify local aromatization, Coulomb repulsion, and countercation position as competing factors that determine where electrons reside in multiply charged finite 1D π-conjugated hydrocarbons.
ER -