An Isolable Bismabenzene: Synthesis, Structure, and Reactivity

Area of Science:

• Organometallic Chemistry
• Aromaticity Studies
• Main Group Chemistry

Background:

• Aromaticity is a fundamental concept in chemistry, typically associated with carbon-based systems.
• Exploring aromaticity in heavier elements remains a significant challenge in synthetic chemistry.
• Bismabenzene, a heavier analog of benzene, offers a unique platform to investigate aromaticity beyond the second row.

Purpose of the Study:

• To synthesize and characterize a stable bismabenzene.
• To experimentally and theoretically evaluate the aromaticity of this heavy benzene analog.
• To demonstrate the chemical reactivity indicative of aromatic stabilization.

Main Methods:

• Synthesis and isolation of the bismabenzene compound.
• Structural characterization using X-ray crystallography.
• Spectroscopic analysis including NMR and UV-vis spectroscopy.
• Theoretical investigations using Density Functional Theory (DFT) calculations.

Main Results:

• A stable, planar bismabenzene ring with unsaturated Bi-C and C-C bonds was successfully synthesized and characterized.
• Experimental data (crystallography, spectroscopy) and DFT calculations indicated a lack of significant bond alternation, consistent with aromaticity criteria.
• The bismabenzene underwent a [4+2] cycloaddition reaction with an alkyne, confirming its aromatic character and stabilization energy.

Conclusions:

• The synthesized bismabenzene represents a stable, planar, aromatic system, extending the concept of aromaticity to sixth-row elements.
• The compound's structural and reactive properties provide strong evidence for its aromatic nature and tangible aromatic stabilization energy.
• This work opens new avenues for exploring aromaticity in novel heavy element compounds.