The heteroaryl-substituted triazolopyridines 3-phenyl-7-(pyrazin-2-yl)-[1,2,3]triazolo[1,5-a]pyridine (2) and 3-[6-(pyridazin-3-yl)-pyridin-2-yl]-[1,2,3]triazolo[1,5-a]pyridine (4) have been synthesized and characterized (by HRMS, IR, 1H and 13C NMR, XRPD, melting point). The crystal structures have been solved from laboratory powder X-ray diffraction data with the direct-space strategy TALP for molecular compounds based on fast local least-squares minimizations. The crystal structure confirmed the formation of the tridentate compound 4 from a ring chain isomerization process. The almost planar arrangement of atoms in both the structures favors the presence of intermolecular π–π interactions, although weak C–H···N electrostatic interactions seem to be also important for the stabilization of the structure. Powder diffraction data have also proved to be sensible enough to determine the relative rotations of the six-membered rings despite the weak difference in scattering power between C and N atoms.

The viability of the direct-space strategy TALP (Vallcorba et al., 2012b) to solve crystal structures of molecular compounds from laboratory powder diffraction data is shown. The procedure exploits the accurate metric refined from a ‘Bragg-Brentano’ powder pattern to extract later the intensity data from a second ‘texture-free’ powder pattern with the DAJUST software (Vallcorba et al., 2012a). The experimental setup for collecting this second pattern consists of a circularly collimated X-ray beam and a 2D detector. The sample is placed between two thin Mylar® foils, which reduces or even eliminates preferred orientation. With the combination of the DAJUST and TALP software a preliminary but rigorous structural study of organic compounds can be carried out at the laboratory level. In addition, the time-consuming filling of capillaries with diameters thinner than 0.3mm is avoided.