Synthesis, crystal structure and Hirshfeld surface analysis of dimethyl 3-(3-bromophenyl)-6-methyl-7-oxo-3,5,6,7-tetrahydropyrazolo[1,2-a]pyrazole-1,2-dicarboxylate

The title compound, C17H17BrN2O5, resulted from the 1,3-dipolar cycloaddition reaction between dimethyl acetylenedicarboxylate and (3-bromobenzylidene)-4-methyl-5-oxopyrazolidin-2-ium-1-ide in CHCl3. The dihedral angle between the pyrazole rings (all atoms) is 32.91 (10)°; the oxo-pyrazole ring displays an envelope conformation whereas the other pyrazole ring adopts a twisted conformation. The bromophenyl ring subtends a dihedral angle of 88.95 (9)° with the mean plane of its attached pyrazole ring. In the crystal, the molecules are linked by C—H...O hydrogen bonds and aromatic π–π interactions with an inter-centroid distance of 3.8369 (10) Å. The Hirshfeld surface analysis and fingerprint plots reveal that the molecular packing is governed by H...H (37.1%), O...H/H...O (31.3%), Br...H/H...Br (13.5%) and C...H/H...C (10.6%) contacts. The energy framework indicates that dispersion energy is the major contributor to the molecular packing.