Weak C-H...O and C-H...N interactions in nitropyrazoles

摘要: The structures of 1-methyl-3-nitro­pyrazole and 1-methyl-4-nitro­pyrazole, C4H5N3O2, have been determined. 3-nitro derivative has crystallographic m-symmetry while the 4-nitro compound no imposed symmetry. significant differences in bond distances angles between are ascribable to electron-withdrawing effects nitro group attached C3 or C4, respectively. In both structures, mol­ecules organized into layers by an extensive network C—H⋯O C—H⋯N hydrogen interactions. Within a layer, arranged similar way, although up 0.3 A analogous H⋯O H⋯N intermolecular observed. cohesion is due van der Waals contacts.