Partitioning of charge in dibenzo[b,g]chrysene: the role of the system's topology

Abstract

Dibenzo[b,g]chrysene dianion (3^2–) shows in its NMR spectrum a partitioning of charge. In the dianion most of the charge is located on the ‘anthracene’ moiety. These observations have been confirmed by MNDO calculations. In the calculations, the location of the lithium cation is taken into account. This unusual phenomenon is connected with the system's paratropicity and with its charge alternation. The NMR assignments were assisted by 2D techniques.