Angewandte Chemie International Edition
Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Cover Picture (Angew. Chem. Int. Ed. Engl. 7/1986)
The cover picture shows pieces of a puzzle of substructures of novel, cyclic conjugated [4n]-π-electron systems. The fragments are shown in the colors of the solutions of the respective “antiaromatics”. Pleiaheptalene (yellow) is the first peri-annelated [4n]-π-electron system without aromatic partial structures. 9b-Methyl-9bH-benz[cd]azulene (blue), a tricyclic annulene, has an almost planar perimeter and shows pronounced paratropism. In contrast, 1,2,5,7-tetra-tert-butyl-s-indacene (red fluorescence), a planar annelated 12π-electron system, exhibits only a slight paratropic ring-current effect with extensive delocalization. More about these novel compounds is reported by K. Hafner et al. on page 630.