Crystal structures and Hirshfeld surface analysis of 5-amino-1-(4-methoxyphenyl)pyrazole-4-carboxylic acid and 5-amino-3-(4-methoxyphenyl)-isoxazole

The title compounds, C11H11N3O3, (I), and C10H10N2O2, (II), are commercially available and were crystallized from ethyl acetate solution. The dihedral angle between the pyrazole and phenyl rings in (I) is 52.34 (7)degrees and the equivalent angle between the isoxazole and phenyl rings in (II) is 7.30 (13)degrees. In the crystal of (I), the molecules form carboxylic acid inversion dimers with an R(8) ring motif via pairwise O-H center dot center dot center dot O hydrogen bonds. In the crystal of (II), the molecules are linked via N-H center dot center dot center dot N hydrogen bonds forming chains propagating along [010] with a C(5) motif. A weak N -H center dot center dot center dot pi interaction also features in the packing of (II). Hirshfeld surface analysis was used to explore the intermolecular contacts in the crystals of both title compounds: the most important contacts for (I) are H center dot center dot center dot H (41.5%) and O center dot center dot center dot H/H center dot center dot center dot O (22.4%). For (II), the most significant contact percentages are H center dot center dot center dot H (36.1%) followed by C center dot center dot center dot H/H center dot center dot center dot C (31.3%).