抄録
Moebius systems are topological objects with only one surface. A Moebius strip can be constructed by affixing the ends of a rectangular strip after twisting it by 180?. In 1964 the Swiss theoretical chemist E. Heilbronner predicted that Moebius-type pi systems (unlike "normal" Hu"ckel annulenes) should be aromatic with 4n electrons. Since then more than 200 theoretical papers were published predicting the properties of potential Moebius aromatics. Many attempts notwithstanding, the experimental proof of Heilbronners statement was pending for more than 40 years.The main reason for the synthetic problems are the high strain energy and the reduced orbital overlap which are induced by the twist of the pi system. This cannot be compensated for by the Moebius-aromatic stabilization. Even if a Moebius annulene could be generated at very low temperatures it would immediately flip the bonds and isomerize to the more stable non-twisted configuration.We developed a general strategy to stabilize the Moebius topology in annulenes in such a way that the Moebius-compounds are thermodynamically more stable than the non-twisted Hueckel isomers. The properties of our Moebius aromatics confirm Heilbronners prediction.
