Towards physical interpretation of Hammett constants: charge transferred between active regions of substituents and a functional group

Abstract

The charges transferred between substituents and two functional groups: nitroso and N,N-dimethylamine in disubstituted benzene rings, were calculated at the B3LYP/cc-pVDZ level, using Natural Population Analysis. They were compared with the charges transferred between active regions of the substituents and of the groups. The transferred charge was well correlated with the Hammett constants, but only when the charges were calculated for the corresponding active regions instead of being calculated for the substituents and functional groups themselves. The results were compared for substituents introduced at the para and meta position to the NO and N(CH3)2 groups.