Crystal structure of 1,7,8,9-tetrachloro-4-(3,5-dichlorobenzyl)-10,10-dimethoxy-4-azatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione

In the title compound, C17H11Cl6NO4, the configuration of the cycloalkene skeleton is endo,cis. The benzene ring is twisted by 58.94 (8)° from the attached pyrrolidine ring. Two carbonyl groups play a key role in the crystal packing. A short intermolecular C⋯O distance of 3.017 (3) Å reveals that one carbonyl group is involved in dipole–dipole interactions, which link two adjacent enantiomers into an inversion dimer. Another carbonyl group provides an acceptor for the weak intermolecular C—H⋯O hydrogen bonds which link these dimers into layers parallel to (011).

In (I), the configuration of the cycloalkene skeleton is endo, cis. The dihedral angle of pyrrolidine ring and benzene ring is 58.94 (8)°. Two carbonyl groups play a key role in the crystal packing (Fig. 2). One carbonyl group is involved in dipole-dipole interactions, with C3···O1(-x+2, -y+2, -z) distance of 3.017 (3) Å, which link two adjacent enantiomers into inversion dimers. The other carbonyl group provides an acceptor for two weak intermolecular C-H···O hydrogen bonds (Table 1). These intermoleclular interactions link these dimers into layers parallel to (011).
The crystals appropriate for X-ray data collection were obtained from acetone solution at room temperature after four days.

S3. Refinement
All H atoms were placed in geometically idealized positions and constrained to ride on their parent atoms with C-H distances of 0.93 Å (0.98 for alicylic CH) for aromatic ring CH, and U iso (H) = 1.2-1.5 U eq (C).

Figure 1
View of (I) showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.