Synthesis, crystal structure and Hirshfeld surface analysis of dimethyl 3-(3-bromo-phen-yl)-6-methyl-7-oxo-3,5,6,7-tetra-hydro-pyrazolo-[1,2-a]pyrazole-1,2-di-carboxyl-ate.

The title compound, C17H17BrN2O5, resulted from the 1,3-dipolar cyclo-addition reaction between dimethyl acetyl-enedi-carboxyl-ate and (3-bromo-benzyl-idene)-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 bromo-phenyl ring subtends a dihedral angle of 88.95 (9)° with the mean plane of its attached pyrazole ring. In the crystal, the mol-ecules are linked by C-H⋯O hydrogen bonds and aromatic π-π inter-actions with an inter-centroid distance of 3.8369 (10) Å. The Hirshfeld surface analysis and fingerprint plots reveal that the mol-ecular 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 mol-ecular packing. © El Ajlaoui et al. 2022.