Crystal structure and Hirshfeld surface analysis of (3aR,4S,7S,7aS)-4,5,6,7,8,8-hexachloro-2-{6-[(3aR,4R,7R,7aS)-4,5,6,7,8,8-hexachloro-1,3-dioxo-1,3,3a,4,7,7a-hexahydro-2H-4,7-methanoisoindol-2-yl]hexyl}-3a,4,7,7a-tetrahydro-1H-4,7-methanoisoindole-1,3(2H)-dione

The asymmetric unit contains one-half of the formula unit of the title compound. The crystal structure is stabilized by intermolecular C—H⋯O, C—H⋯Cl and C—Cl⋯π interactions, and short intermolecular Cl⋯O and Cl⋯Cl contacts, forming a three-dimensional network.

The molecule of the title compound, C 24 H 16 Cl 12 N 2 O 4 , is generated by a crystallographic inversion centre at the midpoint of the central C-C bond. A kink in the molecule is defined by a torsion angle of À169.86 (15) about this central bond of the alkyl bridge. The pyrrolidine ring is essentially planar [max. deviation = 0.014 (1) Å ]. The cyclohexane ring has a boat conformation, while both cyclopentane rings adopt an envelope conformation. In the crystal structure, molecules are linked by intermolecular C-HÁ Á ÁO, C-HÁ Á ÁCl and C-ClÁ Á Á interactions, and short intermolecular ClÁ Á ÁO and ClÁ Á ÁCl contacts, forming a three-dimensional network.
In order to visualize the intermolecular interactions (Table 2) in the crystal of the title compound, a Hirshfeld surface analysis was carried out using Crystal Explorer 17.5 (Turner et al., 2017). The molecular structure of the title compound with displacement ellipsoids for the non-hydrogen atoms drawn at the 50% probability level. [Symmetry code: (a) 2 À x, 1 À y, Àz].

Figure 2
Crystal packing of the title compound viewed along the a-axis direction. C-HÁ Á ÁO, C-HÁ Á ÁCl hydrogen bonds and C-ClÁ Á Á interactions (Table 1)   Crystal packing viewed along the b axis, with intermolecular interactions shown as in Fig. 2. H atoms not involved in hydrogen bonding are omitted for clarity. Table 1 Hydrogen-bond geometry (Å , ).

Figure 4
A view of the Hirshfeld surface for the title compound, plotted over d norm in the range À0.1922 to 1.7149 a.u. together with interacting neighbouring molecules. ecules, forming a cyclic R 4 4 (48) ring motif (Bernstein et al., 1995). The molecules are stacked in layers held together by offsetinteractions, with a centroid-centroid distance of 3.564 (1) Å for the pyrrolidine and benzene rings. There is also an intermolecular C-ClÁ Á Á interaction present.
In the crystal of QOVCAH, the cyclohexene ring adopts a boat conformation, and the five-membered rings have envelope conformations with the bridging atom as the flap. Their mean planes are oriented at a dihedral angle of 86.51 (7) . The molecular structure is stabilized by a short intramolecular C-HÁ Á ÁO contact. In the crystal, molecules are linked by O-HÁ Á ÁO hydrogen bonds, forming chains propagating along [100]. The chains are linked by C-HÁ Á Á interactions, forming slabs parallel to (001).
The compound MOJFUP crystallizes in the triclinic space group P1 with two molecules, A and B, in the asymmetric unit, and MOJGAW in the monoclinic space group P2 1 /n with one molecule per asymmetric unit. The synthesis of both compounds is conducted using endo starting materials, and the same configuration is observed in the resulting crystal structures. In MOJFUP, steric interactions between the orthofluorine atoms and the carbonyl oxygen atoms prevents free rotation about the nitrogen-ipso-carbon bond, which is evidenced by separate 19 F NMR peaks in solution for the ortho-F atoms. In molecule A, the 2,3,5,6-tetrafluoropyridine plane is rotated by 58.05 (5) relative to the pyrrolidine plane and the corresponding dihedral angle for molecule B is 61.65 (7) . The addition of an oxygen atom between N and C in the bridge between the ring systems in MOJGAW alleviates this steric restriction and only one 19 F NMR peak in solution is observed for the ortho-F atoms; even so, the dihedral angle between the 2,3,5,6-tetrafluoropyridine and pyrrolidine planes in the crystal of MOJGAW of 84.01 (5) is larger than that found in MOJFUP.
The main directional interactions in the crystal structures of MOJFUP and MOJGAW are of the type C-HÁ Á ÁO, C-HÁ Á ÁF, C-OÁ Á Á, and C-FÁ Á Á. In both compounds, weak hydrogen-bonding interactions are observed for the hydrogen atom(s) to the carbonyl groups (C-HÁ Á ÁO and C-HÁ Á ÁF in MOJFUP; C-HÁ Á ÁO in MOJGAW) and the olefinic hydrogen atoms (C-HÁ Á ÁF in MOJFUP; C-HÁ Á ÁO in MOJGAW). A weak interaction is also observed for a bridge hydrogen atom in MOJGAW, C-HÁ Á ÁF. The packing is further aided byinteractions with the pyridine ring in MOJGAW.