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Acta Cryst. (2013). E69, o343-o344
[ doi:10.1107/S1600536813003188 ]

Bis(2-carboxy-N-{[1-(2-hydroxyethyl)-3,3-dimethylindolin-2-ylidene]methylimino}anilinium) sulfate monohydrate

G. J. Gainsford, M. Ashraf and A. J. Kay

Abstract: The asymmetric unit of the title compound, 2C20H22N3O3+·SO42-·H2O, contains four cations, two sulfate anions and two lattice water molecules. One of the four cations shows a different conformation of the hydroxyethyl group; the remaining three are all essentially superimposable. Two cations exhibit two-site orientational disorder [ratios = 0.524 (5):0.476 (5) and 0.616 (6):0.384 (6)] of the last two atoms of their hydroxyethyl groups, and one water molecule is disordered over two positions in a 0.634 (13):0.366 (13) ratio. Each imine H atom is intramolecularly in contact with the adjacent carboxyl O atom, forming an S(6) motif, while all the carboxylic acid H atoms are hydrogen bonded to O atoms of the sulfate anions. Other notable hydrogen-bond interactions involve (methylene, phenyl and imine chain) C-H...O (sulfate and carboxyl) and O-H...O(water) contacts, making up a comprehensive three-dimensional network involving D22(n), with n = 4-6 and 15-16, and C22(17) classical hydrogen-bond motifs. The crystal investigated was twinned by pseudomerohedry with a twin component ratio of 0.4745 (12):0.5255 (12).

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