Isolable radical cation and dication of dialumene

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Redox Chemistry

Background:

• Alkenes readily form radical cations and dications upon oxidation, with established applications.
• Dialumenes, aluminum analogues of alkenes, were theoretically predicted to form similar charged species.
• Previous attempts to synthesize dialumene cations were unsuccessful due to aluminum's electrophilicity.

Purpose of the Study:

• To synthesize and characterize stable dialumene-derived radical cations and dications.
• To investigate the redox behavior and reactivity of these novel aluminum species.

Main Methods:

• Synthesis of aluminum complexes featuring bulky silyl substituents and electron-donating carbene ligands.
• Electrochemical studies to induce and analyze oxidation states.
• Spectroscopic characterization of neutral, radical cationic, and dicationic forms.
• Reactivity studies of the dicationic species in Lewis acid catalysis, deoxygenation, and homologation reactions.

Main Results:

• Successful synthesis of stable aluminum-centered radical cation and dication.
• Demonstration of redox reversibility between neutral, radical cationic, and dicationic states.
• The dication exhibited Lewis acidity and mediated deoxygenation and isocyanide homologation reactions.

Conclusions:

• Stable dialumene radical cations and dications can be synthesized using sterically demanding substituents and electron-donating ligands.
• These aluminum species form a redox-reversible system, expanding the known chemistry of main group elements.
• The dialumene dication displays versatile reactivity, highlighting potential applications in catalysis and synthesis.