Ring Currents in Pentacyclic Hydrocarbons

Abstract

McWeeny's modification of London's molecular orbital theory of π‐electron ring currents has been used to calculate the individual currents in the 15 pentacyclic hydrocarbons. The results, useful in themselves for the calculation of NMR chemical shifts, are also significant in the light of what they shed on the question of the range of validity of the assumption that the current in each ring is approximately equal to the benzene ring current.