title: Azatrioxa[8]circulenes: planar anti-aromatic cyclooctatetraenes.
abstract: 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.
authors: Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark.
authors: Christian B
authors: CB
authors: Nielsen
authors: Theis
authors: T
authors: Brock-Nannestad
authors: Peter
authors: P
authors: Hammershøj
authors: Theis K
authors: TK
authors: Reenberg
authors: Magnus
authors: M
authors: Schau-Magnussen
authors: Denis
authors: D
authors: Trpcevski
authors: Thomas
authors: T
authors: Hensel
authors: Roberto
authors: R
authors: Salcedo
authors: Gleb V
authors: GV
authors: Baryshnikov
authors: Boris F
authors: BF
authors: Minaev
authors: Michael
authors: M
authors: Pittelkow