Crystal structure of 6-(4-chlorophenyl)-6a-nitro-6,6a,6b,7,9,11a-hexahydrospiro[chromeno[3′,4′:3,4]pyrrolo[1,2-c]thiazole-11,11′-indeno[1,2-b]quinoxaline] chloroform monosolvate

In the title compound, C33H23ClN4O3S·CHCl3, the thiazole ring adopts an envelope conformation with the N atom as the flap, and the pyrrolidine ring adopts a half-chair conformation. The thiazole ring mean plane makes a dihedral angle of 59.31 (1)° with the pyrrolidine ring mean plane, 71.67 (1)° with the chromene ring and 82.59 (1)° with the chlorobenzene ring. An intramolecular C—H⋯N hydrogen bond occurs. In the crystal, a second C—H⋯N hydrogen bond links the main and solvent molecules. The solvent chloroform molecule is disordered about two positions with an occupancy ratio of 0.508 (14):0.492 (14).

In the crystal, the molecular structure has an intramolecular C-H···N hydrogen bond. The crystal packing of the title compound viewed down the 'a′ axis is shown in Fig. 2. The solvent molecule (CHCl 3 ) has an intermolecular C-H···N hydrogen bond (Table. 1.).

S3. Refinement
The hydrogen atoms were placed in calculated positions with C-H = 0.93Å to 0.98Å, refined in the riding model with fixed isotropic displacement parameters:U iso (H) = 1.5U eq (C) for methyl group and U iso (H) = 1.2U eq (C) for other groups. In bond distance between the carbon and chlorine atom was restrained to 1.782 (1) Å.

Figure 1
The molecular structure of the title compound, showing the atomic numbering and displacement ellipsoids drawn at 30% probability level. For the sake of clarity, the solvent molecule CHCl 3 is omitted.

Figure 2
The crystal packing of the title compound viewed down the 'a′ axis. H-atoms not involved in H-bonds have been excluded for clarity.

Refinement
Refinement on F 2 Least-squares matrix: full R[F 2 > 2σ(F 2 )] = 0.043 wR(F 2 ) = 0.121 S = 1.04 6440 reflections 443 parameters 10 restraints Primary atom site location: structure-invariant direct methods Secondary atom site location: difference Fourier map Hydrogen site location: inferred from neighbouring sites H atoms treated by a mixture of independent and constrained refinement where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.26 e Å −3 Δρ min = −0.35 e Å −3 Special details 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 Occ.