Hydrogen atom or proton transfer in neutral and single positive ions of salicylic acid and related compounds

The characteristics of the process of hydrogen or proton transfer in neutral and single positive ions of salicylic acid, o-hydroxybenzaldehyde, and salicylaldimine were investigated using the B3LYP density functional method. Single-point computations at the CCSD(T) level were also conducted. For neutral systems, the reaction corresponds to a proton transfer process coupled with an electronic transfer, which leads to a compound with nonzwitterionic character. A similar behavior is seen for ionized pi radical cations.