Fully conjugated tetraborylethylene: selenium mediated C-C double bond formation from diborylcarbenoid

Area of Science:

• Organometallic Chemistry
• Materials Science
• Organic Electronics

Background:

• Heteroatom-substituted ethylenes are crucial for electronic devices.
• π-acceptor substituted ethylenes are less explored than π-donors.
• Boron is a potential π-acceptor, but fully conjugated tetraborylethylenes (TBE) were unreported.

Purpose of the Study:

• To synthesize the first fully conjugated tetraborylethylene (TBE).
• To investigate the electronic properties of TBE.
• To explore novel π-acceptor materials for electronic applications.

Main Methods:

• Selenium-mediated C-C double bond formation.
• Synthesis from diborylcarbene (DBC) synthetic equivalents.
• Characterization of intermediates and the final TBE product.
• Density Functional Theory (DFT) calculations.

Main Results:

• The first fully conjugated tetraborylethylene (TBE) was successfully synthesized.
• An intermediate, bis(diborylmethylene)-λ⁴-selane, was confirmed.
• TBE exhibits an elongated C-C bond length (1.368(2) Å) due to π-electron deficiency.
• DFT calculations revealed a low-lying LUMO (-1.75 eV) attributed to boron p-orbitals.

Conclusions:

• The synthesis of TBE represents a significant advancement in π-acceptor chemistry.
• The unique electronic structure of TBE, with its low-lying LUMO, suggests potential for electronic device applications.
• This work expands the scope of conjugated organic materials for future technologies.