Crystal structures and Hirshfeld surface analysis of 5-amino-1-(4-methoxyphenyl)pyrazole-4-carbox-ylic 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) and the equivalent angle between the isoxazole and phenyl rings in (II) is 7.30 (13). In the crystal of (I), the molecules form carboxylic acid inversion dimers with an R(8) ring motif via pairwise O—H. . .O hydrogen bonds. In the crystal of (II), the molecules are linked via N—H. . .N hydrogen bonds forming chains propagating along [010] with a C(5) motif. A weak N—H. . . 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. . .H (41.5%) and O. . .H/H. . .O(22.4%). For (II), the most significant contact percentages are H. . .H (36.1%) followed by C. . .H/H. . .C (31.3%).