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Updated: Dec 15, 2025

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Modelling aromatisation of (BN)nH2n azabora-annulenes
Cate S Anstöter1, Christopher M Gibson1, Patrick W Fowler1
1Department of Chemistry, University of Sheffield, Sheffield, S3 7HF, UK. cate.anstoter@temple.edu p.w.fowler@sheffield.ac.uk.
Borazine is not aromatic, despite its
Area of Science:
- * Inorganic Chemistry
- * Theoretical Chemistry
- * Quantum Chemistry
Background:
- * Borazine is traditionally described as an "inorganic benzene" but lacks aromaticity by magnetic criteria.
- * Neutral (BN)nH2n azabora-annulenes are π-isoelectronic with [2n]annulenes but exhibit localized, not global, π-currents.
- * Nitrogen lone pairs dominate π-currents in planar azabora-annulenes, preventing aromaticity.
Purpose of the Study:
- * To investigate conditions for achieving global ring currents and aromaticity in azabora-annulenes.
- * To explore the magnetic properties of larger azabora-annulene systems.
Main Methods:
- * Calculation of induced current density using the ipsocentric approach.
- * Ab initio calculations to study azabora-annulenes with varying ring sizes and charges.
- * Analysis of π-electron counts and potential energy surfaces for planar conformations.
Main Results:
- * Azabora-annulenes with [8]- and larger rings can support global diatropic ring currents with (4N + 2) π electrons.
- * Charged azabora-annulenes typically adopt higher-order stationary points, not minima.
- * The borazocine dianion ([B4N4H8]2-) is planar, aromatic, and comparable to benzene.
Conclusions:
- * Aromaticity in azabora-annulenes is achievable through strategic π-electron modification and larger ring systems.
- * The borazocine dianion is a promising candidate for an aromatic azabora-annulene and may form sandwich compounds.
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