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A Lewis Superacidic Borirane Derivative Featuring a Tris(Carboranyl)Borane Environment
Libo Xiang1, Junyi Wang2, Alexander Matler1
1Institute for Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg 97074, Germany.
Inorganic Chemistry
|December 12, 2025
Summary
A novel carborane-fused borirane exhibits enhanced Lewis superacidity, surpassing antimony pentafluoride. This unique compound displays unprecedented reactivity due to combined Lewis superacidity and ring strain.
Area of Science:
- Organoboron chemistry
- Supramolecular chemistry
Background:
- Boriranes are strained three-membered boron-containing heterocycles.
- Carboranes are a class of compounds containing boron, carbon, and other atoms.
- Lewis superacids are strong Lewis acids with enhanced reactivity.
Purpose of the Study:
- To synthesize and characterize a novel carborane-fused borirane.
- To investigate the Lewis acidity and reactivity of the synthesized compound.
- To explore the potential of this compound as a Lewis superacid and in novel chemical transformations.
Main Methods:
- Synthesis via salt elimination reaction between lithium carborane and a carboranylboron dibromide.
- Full characterization using solid-state and solution-state techniques (e.g., NMR, X-ray crystallography).
- Evaluation of Lewis acidity through fluoride ion affinity (FIA) measurements.
Main Results:
- Successful synthesis of the carborane-fused borirane (C2B10H10)B(C2B10H10iPr).
- Demonstrated Lewis superacidity, exceeding that of SbF5, due to the tris(carboranyl)borane environment.
- Observed unprecedented reactivity, including transfer hydrogenation, THF ring-opening via σ-bond metathesis, and dearomative N-C bond insertion.
Conclusions:
- The synthesized carborane-fused borirane is the first borirane classified as a Lewis superacid.
- The combination of Lewis superacidity and ring strain enables unique chemical reactivity.
- This study opens new avenues in organoboron chemistry and catalysis.
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