5-Chloro-5′′-(4-chlorobenzylidene)-4′-(4-chlorophenyl)-1′′-ethyl-1′-methyldispiro[indoline-3,2′-pyrrolidine-3′,3′′-piperidine]-2,4′′-dione

Two spiro links are found in the title compound, C31H28Cl3N3O2, one connecting the piperidine and pyrrolidine rings, and the other connecting the pyrrolidine ring and indole residue. The piperidine ring adopts a half-chair conformation, in which the C atom connected to the spiro-C atom lies 0.741 (3) Å out of the plane of the remaining five atoms (r.m.s. deviation = 0.053 Å). The pyrrolidine ring has an envelope conformation with the flap atom being the methylene C atom. Centrosymmetric eight-membered {⋯HNCO}2 amide dimers are the most significant feature of the crystal packing. These are connected into layers parallel to (-120) by C—H⋯O and π–π interactions between pyrrolidine-bound benzene rings [inter-centroid distance = 3.8348 (15) Å]. Slipped face-to-face interactions between the edges of pyrrolidine-bound benzene [shortest C⋯C separation = 3.484 (4) Å] connect the layers into a three-dimensional architecture.

Two spiro links are found in the title compound, C 31 H 28 Cl 3 N 3 O 2 , one connecting the piperidine and pyrrolidine rings, and the other connecting the pyrrolidine ring and indole residue. The piperidine ring adopts a half-chair conformation, in which the C atom connected to the spiro-C atom lies 0.741 (3) Å out of the plane of the remaining five atoms (r.m.s. deviation = 0.053 Å ). The pyrrolidine ring has an envelope conformation with the flap atom being the methylene C atom. Centrosymmetric eight-membered {Á Á ÁHNCO} 2 amide dimers are the most significant feature of the crystal packing. These are connected into layers parallel to (120) by C-HÁ Á ÁO and interactions between pyrrolidine-bound benzene rings [inter-centroid distance = 3.8348 (15) Å ]. Slipped face-to-face interactions between the edges of pyrrolidine-bound benzene [shortest CÁ Á ÁC separation = 3.484 (4) Å ] connect the layers into a three-dimensional architecture.   Table 1 Hydrogen-bond geometry (Å , ).

Refinement
The C-bound H atoms were geometrically placed (C-H = 0.93-0.98 Å) and refined as riding with U iso (H) = 1.2-1.5U eq (C). The N-bound H-atom was treated similarly with N-H = 0.86 Å, and with U iso (H) = 1.2U eq (N).

Results and discussion
Spiropyrrolidine derivatives are known to have biological activity and the basic sketal structure has been well established by X-ray crystallography (Kumar et al. 2008). In continuation of our biological and crystallographic studies of such derivatives (Girgis et al. 2012;Farag et al. 2013), the title compound, (I), was synthesised and characterised crystallographically.
Two spiro links exist in (I), Fig. 1, namely where the piperidine and pyrrolidine rings are connected at C1, and where the pyrrolidine ring and indole residue are connected at C6. The phenylmethylidene and pyrrolidine-bound aryl residues are connected to the piperidine ring at positions C4 and C8, respectively. The conformation about the C4═C11 double bond is E. The sp 3 character of the piperidine-N1 atom is confirmed by the sum of the angles about this atom, i.e. 335 °.
The piperidine ring adopts a half-chair conformation where the C2 atom lies 0.741 (3) Å out of the plane of the remaining five atoms (r.m.s. deviation = 0.0527 Å). The C6 and C8 atoms occupy axial and equatorial positions with respect to the piperidine ring, the phenylmethylidene residue occupies an equatorial position, and the N-bound methyl substituent is equatorial. The pyrrolidine ring has an envelope conformation with the flap atom being the C7 atom which lies 0.607 (4) Å out of the plane of the remaining four atoms (r.m.s. deviation = 0.0536 Å).

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