Dualism of 1,2,4-oxadiazole ring in noncovalent interactions with carboxylic group

• A series of carboxylic acids bearing 1,2,4-oxadiazole substituent were prepared • Noncovalent interactions between carboxylic group and oxadiazole ring were revealed • These interactions have dispersive nature A number of cyclohexane and cyclohexene carboxylic acids bearing 1,2,4-oxadiazole substituent were prepared via condensation of amidoximes with anhydrides of corresponding dicarboxylic acids. All prepared compounds were studied via HRMS, 1 H and 13 C NMR. In addition, for five acids crystalline structures were obtained via X-ray diffraction analysis. Inspection of these X-ray structures revealed two type previously undescribed noncovalent interactions between oxadiazole ring and carboxylic group: O(carboxyl)···C(oxadiazole) and O(oxadiazole)···C(carboxyl). Computational investigation by a number of theoretical approaches (the quantum theory of atoms in molecules, the independent gradient model, natural bond orbital, molecular electrostatic potential, and Kohn-Sham energy decomposition analyses, as well as the domain based local pair-natural orbital coupled-cluster and atomic-dipole-moment-corrected Hirshfeld methods) demonstrated that these interactions are caused by the packing effect and have an electrostatic and dispersive nature. Graphical Abstract .