Abstract:
Substituent effects in C6H5X. . .M+ (M+ = Li+, Na+, K+, and NHþ4) systems have been characterized using isotropic nuclear magnetic shielding constants (r). Good linear relationship between r and the Hammett
substituent constant rp is established which suggests that the substituent effects can be quantified by NMR experiments. Irrespective of the electronic nature of X, meta carbons, and all the hydrogens are always deshielded and this property is useful for detecting cation–p interaction. The r-scan plots
revealed that the deshielding effect of the cation on the aromatic ring is significant even at large cation–p distance ( 4.5 Å)
