Nitrogen-doped heptazethrene and octazethrene diradicaloids.

Area of Science:

• Organic Chemistry
• Materials Science
• Quantum Chemistry

Background:

• Nitrogen-doped polycyclic aromatic hydrocarbons are of interest for their unique electronic properties.
• Diradicaloids, molecules with significant diradical character, exhibit fascinating reactivity and magnetic behavior.

Purpose of the Study:

• To synthesize and characterize nitrogen-doped heptazethrene (HZ) and octazethrene (OZ) diradicaloids.
• To investigate the electronic properties and ground states of these novel nitrogen-doped systems.
• To explore the reactivity differences between HZ-2N and OZ-2N.

Main Methods:

• One-pot Buchwald-Hartwig amination followed by intramolecular cyclization for precursor synthesis.
• Chemical oxidation to generate the target dicationic diradicaloids.
• Spectroscopic and computational methods to determine electronic properties and diradical character.

Main Results:

• Stable N-aryl substituted dications, HZ-2N and OZ-2N, were successfully synthesized.
• HZ-2N exhibits an open-shell singlet ground state with 27.2% diradical character and a small singlet-triplet energy gap.
• OZ-2N, with a higher diradical character (54.7%), demonstrated increased reactivity, undergoing hydrogen abstraction.

Conclusions:

• Nitrogen doping significantly influences the electronic structure and diradical character of heptazethrene and octazethrene systems.
• The degree of diradical character dictates the reactivity of these diradicaloids.
• These findings open avenues for designing novel organic materials with tunable electronic and magnetic properties.