Fukui function as a descriptor of the imidazolium protonated cation resonance hybrid structure.

The Lewis structures that contribute to the imidazolium protonated cation resonance hybrid can be explained in a unified way in terms of the Fukui function (density functional descriptor) and the local hard and soft acids and bases principle. The results obtained open the possibility of analyzing the resonance contributors and the resonance hybrid in terms of the electronic density. [structure--see text]