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Direct Interconversion between Bis(borylenes) and Diborenes
Sourav Kar1,2, Koushik Saha1,2, Vailappully Binilkrishna1,2
1Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Journal of the American Chemical Society
|November 18, 2025
Summary
Researchers report novel ferrocene-based borylene systems. A unique diborene formed from bis(borylene) reversibly dissociates, demonstrating a Wanzlick-type equilibrium crucial for borylene chemistry.
Area of Science:
- Organometallic Chemistry
- Carbene Chemistry
- Boron Chemistry
Background:
- Borylenes and diborenes are key boron compounds with limited understanding of their equilibrium.
- Wanzlick-type equilibria between low-coordinate boron species and their dimers are not well-established.
Purpose of the Study:
- To synthesize and characterize novel ferrocene-based borylene and diborene systems.
- To investigate the Wanzlick-type equilibrium between borylenes and diborenes using ferrocene scaffolds.
- To explore the reactivity and properties of these unique organoboron compounds.
Main Methods:
- Synthesis of cyclic (alkyl)(amino)carbene (CAAC)-stabilized ferrocene-based borylenes.
- Characterization of mono- and disubstituted ferrocene borylene systems.
- Investigation of intramolecular C-H, CO, and H2 activation reactions.
- Analysis of the reversible coupling and decoupling between bis(borylene) and diborene species.
Main Results:
- Reported CAAC-stabilized mono- and disubstituted ferrocene-based borylenes.
- Observed intramolecular C-H, CO, and H2 activation in monosubstituted borylenes.
- Synthesized a diborene from a disubstituted ferrocene bis(borylene) featuring a delocalized four-center-two-electron (4c-2e) π bond.
- Demonstrated reversible dissociation of the diborene back to bis(borylene), establishing a Wanzlick-type equilibrium.
Conclusions:
- The ferrocene scaffold's electronic and rotational flexibility facilitates reversible bis(borylene)-diborene coupling.
- The observed reversible equilibrium provides direct evidence for Wanzlick-type behavior in borylene chemistry.
- Ferrocenyl diborene species exhibit unique photophysical, redox, and reactive properties.
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