Relationship between electrophilicity index, Hammett constant and nucleus-independent chemical shift

Inter-relationships between the electrophilicity index (w), Hammett constant (óp) and nucleusindependent chemical shift (NICS (1) – NICS value one å ngstrom above the ring centre) have been investigated for a series of meta- and para-substituted benzoic acids. Good linear relationships between Hammett constant vs electrophilicity and Hammett constant vs NICS (1) values have been observed. However, the variation of NICS (1) against w shows only a low correlation coefficient.