Ring signatures for benzenoids with up to seven rings,Part 1: Catacondensed systems

We revisited the π‐electron ring partitions in catacondensed benzenoids and re‐examined structural regularities reported for the ring partitions in these compounds, seeking the origin of the observed regularities. We examined the distribution of the π‐electron ring partitions by counting the contributions arising from benzene rings having different assigned numbers of π‐electrons. This has led to a better insight into the underlying structure of the π‐electron ring partitions and also to a novel and unique π‐electron “signature” of individual rings in benzenoid hydrocarbons. The physical interpretation of the local π‐electron ring partition represents the local π‐electron density of benzenoid molecules, and is not an alternative index of local aromaticity as one may erroneously assume. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008