Isolable radical cation and dication of dialumene

TL;DR

Scientists synthesized stable aluminum compounds that can switch between different charged states, opening new possibilities for chemical reactions.

Contribution

The first synthesis of isolable dialumene-derived radical cation and dication using bulky silyl and carbene ligands.

Findings

Aluminum complexes can reversibly switch between neutral, radical cationic, and dicationic states.

The dication shows reactivity as a Lewis acid and can mediate deoxygenation and isocyanide homologation.

Bulky silyl and carbene ligands stabilize the electron-deficient aluminum species.

Abstract

Alkenes are known to undergo successive oxidation to form alkene-derived radical cations and dications, which have found applications across various fields. As the aluminum analogues of alkenes, dialumenes likewise have the potential to lose one or two π-bonding electrons, forming dialumene-derived radical cations or dications. To date, however, these species have remained elusive, most likely due to the intrinsic electron deficiency imposed by both the positive charge and the pronounced electrophilicity of aluminum. Here, we present the synthesis of a stable aluminum-centered radical cation and dication through the combination of bulky silyl substituents and electron-donating carbene ligands. Further studies reveal that these aluminum complexes can switch between their neutral, radical cationic, and dicationic states, thus establishing a redox-reversible system. Furthermore, the dication exhibits multiple modes of reactivity, acting as a Lewis acid while also mediating both deoxygenation reactions and isocyanide homologation.

As the aluminum analogues of alkenes, dialumenes have the potential to lose one or two π-bonding electrons, forming dialumene-derived radical cations or dications, but they are challenging to isolate due to intrinsic electron deficiency. Here, the authors present the synthesis of a stable aluminum-centered radical cation and dication.

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