Proton transfer from H₂O to p-substituted anilide anion: can the size of water cluster influence the N⁻···H-OH→N-H···OH⁻ switching.

The effects of the H(2)O cluster size and the substituent (X=H, Me, OMe, CHO, NO and NO(2)) in the para position of anilide ion on the HN⁻···H-OH→HN-H···OH⁻ switching were investigated by means of B3LYP and MP2 methods. The changes in the H-bond strength due to variation of the substituent and H(2)O cluster size were well monitored by changes in the interaction energy, structural parameter, electron density topology, natural charge, charge transfer and percentage of p-character of N atom in the C-N bond. The HN(-)[Symbol: see text][Symbol: see text][Symbol: see text]H-OH→HN-H[Symbol: see text][Symbol: see text][Symbol: see text]OH(-) switching was enhanced by an increase in the extent of solvation and the insertion of the electron-donating substituents in the para position. The results demonstrate that the strength of the HN(-)∙∙∙HO H-bond increases and that of NH∙∙∙OH(-) H-bond decreases by electron-donating substituents. The reverse situations were found for electron-accepting substituents.