Reactivity patterns of imidazole, oxazole, and thiazole as reflected by the polarization justified Fukui functions.

The concept of the polarization justified Fukui functions has been tested for the set of model molecules: imidazole, oxazole, and thiazole. Calculations of the Fukui functions have been based on the molecular polarizability analysis, which makes them a potentially more sensitive analytical tool as compared to the classical density functional theory proposals, typically built on electron density only. Three selected molecules show distinct differences in their reactivity patterns, despite very close geometry and electronic structure. The maps of the polarization justified Fukui functions on the molecular plane correctly identify important features of the molecules: the site for the preferential electrophilic attack in imidazole (-NH, see the TOC image) and oxazole (5-C), as well as uniquely aromatic character of the thiazole molecule and the acidic forms XH(+) of all three species.