4′-(4-Chlorophenyl)-1′-methyldispiro[indan-2,2′-pyrrolidine-3′,2′′-indan]-1,3,1′′-trione

In the title compound, C27H20ClNO3, the two cyclopentane rings adopt envelope conformations. The pyrrolidine ring also adopts an envelope conformation (with the spiro C atom as the flap) and its least-squares plane (fitted to five atoms) makes dihedral angles of 66.50 (9), 77.36 (8) and 73.76 (8)° with the chlorobenzene ring and the two 2,3-dihydro-1H-indene ring systems, respectively. The molecular conformation is stabilized by an intramolecular C—H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, molecules are linked by C—H⋯O hydrogen bonds into chains running parallel to the [001] direction.

In the title compound, C 27 H 20 ClNO 3 , the two cyclopentane rings adopt envelope conformations. The pyrrolidine ring also adopts an envelope conformation (with the spiro C atom as the flap) and its least-squares plane (fitted to five atoms) makes dihedral angles of 66.50 (9), 77.36 (8) and 73.76 (8) with the chlorobenzene ring and the two 2,3-dihydro-1Hindene ring systems, respectively. The molecular conformation is stabilized by an intramolecular C-HÁ Á ÁO hydrogen bond, which generates an S(6) ring motif. In the crystal, molecules are linked by C-HÁ Á ÁO hydrogen bonds into chains running parallel to the [001] direction.

Refinement
All H atoms were positioned geometrically and refined using a riding model with C-H = 0.95-1.00 Å and U iso (H) = 1.2 or 1.5 U eq (C). A rotating-group model was applied for the methyl group. The highest residual electron density peak is located at 0.73 Å from atom C10 and the deepest hole is located at 0.49 Å from atom Cl1. Fig. 1. The molecular structure of the title compound showing 50% probability displacement ellipsoids for non-H atoms. The intramolecular hydrogen bond is shown as a dashed line.   Glazer, 1986) operating at 100.0 (1) K.

sup-2 Figures
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Cl1 1.36538 (5