A Dissected Ring Current Model for Assessing Magnetic Aromaticity: A General Approach for both Organic and Inorganic Rings

A model based on classical electrodynamics is used to measure the strength of ring currents of different molecular orbitals, i.e., sigma- and pi-orbitals, and characteristics of ring current loops, i.e., ring current radii and height of current loops above/below the ring planes, among a number of organic as well as inorganic molecules. For the pi-current, the present model represents an improvement of previous approaches to determine ring current intensity. It is proven that the present model is more precise than previous models as they could not explain presence of the minimum in the plot of NICS pi zz versus distance close to the ring plane. Variations in the charge of molecules and the types of constituent atoms of each species affect the ring current radii of both sigma- and pi-current loops as well as the height of pi-current loops above/below the ring plane. It is suggested that variation in the distribution of the one-electron density in different systems is the main source of differences of the ring current characteristics. (C) 2011 Wiley Periodicals, Inc. J Comput Chem 32: 2422-2431, 2011