-2,6-Di(isopropyl)phenyl-2-azaphenalenyl radical cations.

-2,6-Di(isopropyl)phenyl-2-azaphenalenyl radical cations were obtained as a dark brown air-sensitive crystalline compound. The high HOMA values and the ACID calculation indicate relatively high aromatic character of a 5,8-di--butyl derivative, and clean generation of a derivative without -butyl groups indicates that the di(isopropyl)phenyl group is sufficient for hampering the formation of the σ-dimer.

Bis-periazulene (Cyclohepta[]fluorene) as a Nonalternant Isomer of Pyrene: Synthesis and Characterization of Its Triaryl Derivatives.

Bis-periazulene (cyclohepta[]fluorene), which is an unknown pyrene isomer, was synthesized as kinetically protected forms. Its triaryl derivatives - exhibited the superimposed electronic structures of peripheral, polarized, and open-shell π-conjugated systems. In contrast to previous theoretical predictions, bis-periazulene derivatives were in the singlet ground state.

Characterization of Benzo[a]naphtho[2,3-f]pentalene: Interrelation between Open-shell and Antiaromatic Characters Governed by Mode of the Quinoidal Subunit and Molecular Symmetry.

The singlet open-shell character and antiaromaticity are intriguing features in π-conjugated carbocycles. These two exhibit similar chemical and physical properties. However, they rarely coexist in the same molecule.

Open-Shell and Antiaromatic Character Induced by the Highly Symmetric Geometry of the Planar Heptalene Structure: Synthesis and Characterization of a Nonalternant Isomer of Bisanthene.

A nonbenzenoid hydrocarbon, difluoreno[1,9,8- alkj:1',9',8'- gfed]heptalene 1, is synthesized. Experimental and theoretical investigations demonstrate that the planar and symmetric heptalene core within 1 effectively induces the antiaromatic and open-shell character. These properties are not shared by bisanthene 2, a benzenoid isomer of 1.