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.

Crystal structure of (E)-3-allyl-2-sulfanyl-idene-5-[(thio-phen-2-yl)methyl-idene]thia-zolidin-4-one.

Mol-ecules of the title compound, C11H9NOS3, are built up by one thio-phene and one 2-thioxa-thia-zolidin-4-one ring which are connected by a methyl-ene bridge. In addition, there is an allyl substituent attached to nitro-gen. The two rings are almost coplanar, making a dihedral angle between them of 0.76 (11)°. The allyl group is oriented perpendicular to the mean plane through both ring systems. The crystal structure exhibits inversion dimers in which mol-ecules are linked by pairs of C-H⋯O hydrogen bonds. Additional π-π inter-actions between neighboring thio-phene and 2-thioxa-thia-zolidin-4-one rings [inter-centroid distance = 3.694 (2) Å] lead to the formation of a three-dimensional network.

Crystal structure of (Z)-3-allyl-5-(3-bromo-benzyl-idene)-2-sulfanyl-idene-1,3-thia-zolidin-4-one.

In the title compound, C13H10BrNOS2, the rhodanine (systematic name: 2-sulfanyl-idene-1,3-thia-zolidin-4-one) and the 3-bromo-benzyl-idene ring systems are inclined slightly, forming a dihedral angle of 5.86 (12)°. The rhodanine moiety is linked to an allyl group at the N atom and to the 3-bromo-benzyl-idene ring system. The allyl group, C=C-C, is nearly perpendicular to the mean plane through the rhodanine ring, maling a dihedral angle of 87.2 (5)°. In the crystal, mol-ecules are linked by pairs of C-H⋯O hydrogen bonds, forming inversion dimers with an R 2 (2)(10) ring motif.

Crystal structure of (Z)-3-allyl-5-(4-chloro-benzyl-idene)-2-sulfanyl-idene-1,3-thia-zolidin-4-one.

In the title compound, C13H10ClNOS2, the dihedral angle between the rhodanine (r.m.s. deviation = 0.008 Å) and 4-chloro-benzyl-idene rings is 1.79 (11)°. The allyl group attached to the N atom, which lies almost perpendicular to the rhodanine ring, is disordered over two orientations in a 0.519 (13):0.481 (13) ratio. A short intra-molecular C-H⋯S inter-action closes an S(6) ring. In the crystal, mol-ecules are linked by π-π stacking inter-actions [centroid-centroid separation = 3.600 (15) Å], generating inversion dimers.

Crystal structure of (Z)-3-allyl-5-(4-methyl-benzyl-idene)-2-sulfanyl-idene-1,3-thia-zolidin-4-one.

In the title compound, C14H13NOS2, the atoms of the allyl group are disordered over two sets of sites, with an occupancy ratio of 0.559 (10):0.441 (10). The rhodanine ring makes a dihedral angle of 5.51 (12)° with the mean plane through the p-tolyl group. There are no specific inter-molecular inter-actions in the crystal packing.