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Updated: Feb 22, 2026

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
Bowl shaped deformation in a planar aromatic polycycle upon reduction. Li and Na separated dianions of the aromatic
T Wombacher1, R Goddard, C W Lehmann
1Fachbereich Chemie, Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Alarich-Weiss Str. 12, 64287 Darmstadt, Germany. joerg.schneider@ac.chemie.tu-darmstadt.de.
Abstract:
Herein we report the synthesis and crystal structures of three light alkali metal salts of the dianion of the polycyclic aromatic hydrocarbon 5,6:11,12-di-o-phenylenetetracene (LDOPT). The compounds are obtained by reaction of LDOPT with an excess of lithium or sodium metal in different O-donor solvents (DME, diglyme) and crystallize as naked, solvated-cation separated dianions exhibiting no interaction between the alkali metal ion and the aromatic π-system of LDOPT. Depending on the aprotic etheral solvent and the hardness of the alkaline metal agent a significant structural perturbation of the conjugated carbon framework of LDOPT is observed resulting in a bowl shaped curvature of the anionic π-perimeter, in contrast to its fully planar neutral state. Reduction of LDOPT with lithium in DME results in the formation of the solvent-separated molecular structure of {[(DME-κ2O)3Li+]2(LDOPT2-)}21 containing naked isolated units of dianionic LDOPT. A similar structural arrangement is observed for the corresponding sodium compound {[(DME-κ2O)3Na+]2(LDOPT2-)}22 in which, however, a lesser curvature of the isolated dianionic ligand skeleton compared to 1 is observed. In contrast to 1 and 2 reduction with sodium in diglyme results in the formation of {[(diglyme-κ3O)2Na+]2(LDOPT2-)}0.53. The deformation of the peripheric phenylene rings of [LDOPT2-] in 3 is not as pronounced as compared to 1 and 2. Nevertheless, molecular structures of 1-3 deviate from full-planarity as observed in the parent neutral LDOPT. No preferential endo- or exo-site coordination of the alkaline metal cations Li+ and Na+ on the curved dianionic π-perimeter is observed.
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