Crystal structure and Hirshfeld surface analysis of 4-(2-chloroethyl)-5-methyl-1,2-dihydropyrazol-3-one

In the crystal of the title compound, C6H9ClN2O, molecular pairs form dimers with an R22(8) motif through N—H. . .O hydrogen bonds. These dimers are connect into ribbons parallel to the (100) plane with R44(10) motifs by N—H. . .O hydrogen bonds along the c-axis direction. In addition, π–π [centroid-to-centroid distance = 3.4635 (9) A◦ ] and C—Cl. . .π interactions between the ribbons form layers parallel to the (100) plane. The three-dimensional consolidation of the crystal structure is also ensured by Cl. . .H and Cl. . .Cl interactions between these layers. According to a Hirshfeld surface study, H. . .H (43.3%), Cl. . .H/H. . .Cl (22.1%) and O. . .H/H. . .O (18.7%) interactions are the most significant contributors to the crystal packing. © 2024 International Union of Crystallography. All rights reserved.