DFT analysis of rotational barriers, 1H and 13C NMR chemical shifts in neutral and protonated furfurylidenanilines

Differences in Mulliken charges for each position in neutral and protonated furfurylidenanilines were correlated with experimental 1H and 13C Substituent Induced Shifts. The experimental trends in 1H and 13C Substituent Induced Shifts were well reproduced by charge differences. Only the functional group 1H shifts do not correlate with the charges reflecting the variable effect of the anisotropy term due to the benzene ring. Protonation of FA removes this variability.