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 R-2(2)(8) motif through N-H center dot center dot center dot O hydrogen bonds. These dimers are connect into ribbons parallel to the (100) plane with R-4(4)(10) motifs by N-H center dot center dot center dot O hydrogen bonds along the c-axis direction. In addition,pi-pi [centroid- to-centroid distance = 3.4635 (9) angstrom] and C-Cl center dot center dot center dot pi interactions between the ribbons form layers parallel to the (100) plane. The three-dimensional consolidation of the crystal structure is also ensured by Cl center dot center dot center dot H and Cl center dot center dot center dot Cl interactions between these layers. According to a Hirshfeld surface study, H center dot center dot center dot H (43.3%), Cl center dot center dot center dot H/H center dot center dot center dot Cl (22.1%) and O center dot center dot center dot H/H center dot center dot center dot O (18.7%) interactions are the most significant contributors to the crystal packing.