Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.004 Å; R factor = 0.038; wR factor = 0.105; data-to-parameter ratio = 13.8.In the title compound, C 18 H 19 BrN 2 O 4 , the chromene unit is not quite planar (r.m.s. deviation = 0.199 Å ), with the methyl C atoms lying 0.027 (4) and 1.929 (4) Å from the mean plane of the chromene unit. The six-membered carbocyclic ring of the chromene moiety adopts an envelope conformation, with the dimethyl-substituted C atom as the flap. The methylamine and nitro groups are slightly twisted from the chromene moiety, with C-N-C-O and O-N-C-C torsion angles of 2.7 (4) and À0.4 (4), respectively. The dihedral angle between the mean plane of the chromene unit and the benzene ring is 85.61 (13) . An intramolecular N-HÁ Á ÁO hydrogen bond generates an S(6) ring motif, which stabilizes the molecular conformation. In the crystal, molecules are linked via N-HÁ Á ÁO hydrogen bonds, forming hexagonal rings lying parallel to the ab plane. A region of disordered electron density, most probably disordered ethanol solvent molecules, occupying voids of ca 432 Å 3 for an electron count of 158, was treated using the SQUEEZE routine in PLATON [Spek (2009). Acta Cryst. D65, 148-155]. Their formula mass and unit-cell characteristics were not taken into account during refinement. Related literature

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In the title compound, C31H25N5O3·C2H6OS, the three indole/indoline units are all essentially planar with maximum deviations of 0.0172 (3), 0.053 (2) and 0.07 (2) Å. The pyrrolidine ring adopts an envelope conformation with the C atoms bearing the 1-ethyl-2-oxo­indole substituent (in which the five-membered ring adopts a twisted conformation) as the flap. The dimethyl sulfoxide solvent mol­ecule is disordered over two positions, with an occupancy factor ratio of 0.871 (4):0.129 (4). The solvent components are linked to the heterocyclic mol­ecule via C—H⋯O and C—H⋯S hydrogen bonds. In the crystal, the solvent components are linked to the heterocyclic molecule via C—H⋯O and C—H⋯S inter­actions, forming R 2 2(10) ring motifs. The mol­ecules are further connected into a chain along the a-axis direction via N—H⋯O hydrogen bonds.

In both title pyridine derivatives, (I) and (II), the cation adopts an E configuration with respect to the C=C. In compound (I), the PF6 − anion is disordered with occupancy factors of 0.614 (7):0.386 (7). In both the compounds, the crystal packing is stabilized by C—H⋯F inter­molecular inter­actions results into two-dimensional mol­ecular sheets, which are formed by (14) ring motifs in compound (I), (40) ring motifs in compound (II). In addition to that, the crystal packing is further stabilized by P—F⋯π inter­actions in compound (I) and π–π in compound (II).

In the title compound, C26H20N4O2S, the central pyrrolidine ring adopts a twist conformation on the C—C bond involving the spiro C atom. Its mean plane makes dihedral angles of 78.83 (14), 65.91 (15) and 44.49 (18)° with the mean planes of the adjacent oxindole ring system, the indole system and the thio­phene ring, respectively. The indole and indoline units are essentially planar, with maximum deviations of 0.019 (3) and 0.090 (3) Å, respectively. In the oxindole fused-ring system, the pyrrole ring adopts an envelope conformation with the spiro C atom as the flap. In the crystal, pairs of N—H⋯O hydrogen bonds link the mol­ecules, forming inversion dimers with an R 2 2(8) ring motif. The dimers are linked by further N—H⋯O hydrogen bonds, forming a two-dimensional network lying parallel to (100).