DOI: 10.1002/jhet.377

Six pyrazolo[1,5-a]pyrimidines bearing a 7-trifluoromethyl (three compounds), a 7-trichloromethyl (two compounds), and a 7-ethoxycarbonyl (one compound) have been structurally characterized. The new X-ray structures of 2-methyl-5-(p-bromophenyl)-7-trifluoromethylpyrazolo[1,5-a]pyrimidine (3) and 2-methyl-7-trichloromethylpyrazolo[1,5-a]pyrimidine (4) are reported. The combined use of GIAO/B3LYP/6-311++G(d,p) calculations with NMR spectroscopy in solution and in the solid state allows to establish some general rules that can be useful for characterizing related compounds. Compounds 3 and 4 present in the solid-state interesting intra- and intermolecular halogen bonds.