Details

Autor(en) / Beteiligte

• Streifel, Benjamin C.
• Zafra, José L.
• Espejo, Guzmán L.
• Gómez‐García, Carlos J.
• Casado, Juan
• Tovar, John D.

Titel

An Unusually Small Singlet–Triplet Gap in a Quinoidal 1,6‐Methano[10]annulene Resulting from Baird’s 4 n π‐Electron Triplet Stabilization

Ist Teil von

• Angewandte Chemie, 2015-05, Vol.127 (20), p.5986-5991

Erscheinungsjahr

2015

Quelle

Wiley Online Library

Beschreibungen/Notizen

• Abstract Within the continuum of π‐extended quinoidal electronic structures exist molecules that by design can support open‐shell diradical structures. The prevailing molecular design criteria for such structures involve proaromatic nature that evolves aromaticity in open‐shell diradical resonance structures. A new diradical species built upon a quinoidal methano[10]annulene unit is synthesized and spectroscopically evaluated. The requisite intersystem crossing in the open‐shell structure is accompanied by structural reorganization from a contorted Möbius aromatic‐like shape in S 0 to a more planar shape in the Hückel aromatic‐like T 1 . This stability was attributed to Baird’s Rule which dictates the aromaticity of 4 n π‐electron triplet excited states.