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Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
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Encapsulation of an Electron in a Diborencine Macrocycle: Synthesis, Structure, and Reactivity
Yuhao Wu1, Yi Pan1, Jiachen Yao1
1Department of Chemistry, State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, P. R. China.
Journal of the American Chemical Society
|September 22, 2025
Summary
Researchers successfully trapped a single electron using a boron-boron one-electron sigma bond in a diborencine macrocycle. This novel electron encapsulation showcases unique structural and reactive properties, advancing molecular design.
Area of Science:
- Inorganic Chemistry
- Supramolecular Chemistry
- Computational Chemistry
Background:
- Encapsulating single electrons is challenging due to electron delocalization.
- Boron-based macrocycles offer potential host systems for electron confinement.
Purpose of the Study:
- To achieve stable single-electron encapsulation within a host system.
- To characterize the electronic and structural properties of a novel one-electron bond.
- To explore the reactivity of the electron-trapping macrocycle.
Main Methods:
- X-ray single-crystal analysis
- Electron Paramagnetic Resonance (EPR) studies
- Density Functional Theory (DFT) computations
- Nuclear Magnetic Resonance (NMR) spectroscopy
- High-Resolution Mass Spectrometry (HRMS)
Main Results:
- Successfully trapped a single electron via a B-B one-electron sigma bond in a diborencine macrocycle (compound 4).
- Characterized the B-B bond, revealing significant s-character and sp3 hybridization of boron atoms.
- Demonstrated rich reactivity of compound 4, including O2 cleavage, ring expansion with disulfides, and ring contraction with diselenides and quinones.
Conclusions:
- The study presents a novel method for single-electron encapsulation using a B-B one-electron sigma bond.
- The characterized macrocycle exhibits unique electronic properties and diverse reactivity.
- DFT studies provide mechanistic insights into the observed reactions.
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