(R,S)-2 '-Amino-6 '-methyl-2,5 ',5 '-trioxo-6 ' H-spiro[indoline-3,4 '-pyrano[3,2-c][2,1]benzothiazine]-3 '-carbonitrile dimethylformamide monosolvate

The title solvate, C20H14N4O4S center dot C3H7NO, comprises a stereogenic centre but the centrosymmetric space group causes the presence of the racemate in the crystal. The spiro-joined fragments are almost orthogonal, with a dihedral angle of 86.8 (2)degrees between the mean planes of the pyrane ring and the dihydroindolone ring system. The atoms of the indolinone bicycle are coplanar, with an r.m.s. deviation of 0.005 angstrom. In the crystal, pairs of N-H center dot center dot center dot O hydrogen bonds link the molecules into centrosymmetric dimers which are linked to the dimethylformamide solvent molecules by further N-H center dot center dot center dot O hydrogen bonds. N-H center dot center dot center dot N hydrogen bonds link neighbouring dimers into [010] chains.