Obtaining relative induced ring currents quantitatively from NICS.
A model for obtaining the sigma-only effect on the nucleus-independent chemical shift (NICS) is introduced. By subtracting the values obtained for the "sigma-only" model from the respective values of the conjugated system it is possible to obtain the NICS values that originate from the pi system only. This procedure allows obtaining a quantitative measure of the relative intensities of diatropic and paratropic ring currents in different systems with a built-in measure of their accuracy. The scope and limitations of the model are discussed.
Stanger
Amnon
A
Schulich faculty of Chemistry and The Lise-Meitner-Minerva Center for Computational Quantum Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel. stanger@tx.technion.ac.il