Synthesis, X-ray characterization and computational Studies of N-imidazolyl and N-pyrazolyl pyrimidine derivatives

In this manuscript we report the synthesis and X-ray characterization of neutral 2-(1H-imidazol-1-yl)-pyrimidine (1), 2-(1H-pyrazol-1-yl)-pyrimidine (2) and 1-(2-pyrimidinyl)-1H-benzimidazole (3). We have also obtained crystals of the corresponding hydrochlorides of compounds 1 and 3. Finally, the outer sphere complex of protonated 2-(1H-imidazol-1-yl)-pyrimidine with [CoCl4]2− as counterion is described. In several charged structures interesting anion–π interactions determine the crystal packing. Moreover, in neutral systems some stacking interactions are governed by double lone pair–π interactions. High level ab initio calculations (RI-MP2/def2-TZVP) have been used to evaluate the noncovalent interactions observed in the solid state and the interplay between them.