The molecular structure of C11H19ClN2O was analyzed, by linking the molecules into sheets by a combination of one C-H··· hydrogen bond and one C-H···π(arene) hydrogen bond. Two very low angle reflections were omitted from the final refinement because of partial attenuation and/or extinction. All hydrogen atoms were located in difference maps and then treated as riding atoms, with C-H = 0.95 Å and U iso(H) = 1.2Ueq(C) for aromatic and aldehyde atoms. The methyl group was modeled using six H-atom sites, all with occupancy 0.5.
Trilleras, J., Quiroga, J., Cobo, J., Low, J. N., & Glidewell, C. (2005). 5-Chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde: Sheets built from C-H⋯O and C-H⋯π(arene) hydrogen bonds. Acta Crystallographica Section E: Structure Reports Online, 61(4). https://doi.org/10.1107/S1600536805007981