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Azatrioxa[8]circulenes: Planar Anti‐Aromatic Cyclooctatetraenes
Author(s) -
Nielsen Christian B.,
BrockNannestad Theis,
Hammershøj Peter,
Reenberg Theis K.,
SchauMagnussen Magnus,
Trpcevski Denis,
Hensel Thomas,
Salcedo Roberto,
Baryshnikov Gleb V.,
Minaev Boris F.,
Pittelkow Michael
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201203113
Subject(s) - cyclooctatetraene , planar , aromaticity , molecule , chemistry , crystal (programming language) , crystallography , computational chemistry , combinatorial chemistry , organic chemistry , computer science , computer graphics (images) , programming language
We describe herein the first synthesis of a new class of anti‐aromatic planar cyclooctatetraenes: the azatrioxa[8]circulenes. This was achieved by treating a suitably functionalised 3,6‐dihydroxycarbazole with 1,4‐benzoquinones or a 1,4‐naphthoquinone. We fully characterised the azatrioxa[8]circulenes by using optical, electrochemical and computational techniques as well as by single‐crystal X‐ray crystallography. The results of a computational study (NICS) suggest that the central planar cyclooctatetraene is anti‐aromatic when the molecules are in neutral or oxidised states (2+), and that the corresponding dianions are aromatic. We discuss the aromatic/anti‐aromatic nature of the planar cyclooctatetraenes and compare them with the isoelectronic tetraoxa[8]circulenes.