Abstract
Crystal structures of the title compound (systematic name: morpholin-4-ium 2,5-di-bromo-4-hy-droxy-3,6-dioxo-cyclo-hexa-1,4-dien-1-olate), C4H10NO(+)·C6HBr2O4 (-), were determined at three temperatures, viz. 130, 145 and 180 K. The asymmetric unit comprises one morpholinium cation and two halves of crystallographically independent bromanilate monoanions, which are located on inversion centres. The conformations of the two independent bromanilate anions are different from each other with respect to the O-H orientation. In the crystal, the two different anions are linked alternately into a chain along [211] through a short O-H⋯O hydrogen bond, in which the H atom is disordered over two positions. The refined site-occupancy ratios, which are almost constant in the temperature range studied, are 0.49 (3):0.51 (3), 0.52 (3):0.48 (3) and 0.50 (3):0.50 (3), respectively, at 130, 145 and 180 K, and no significant difference in the mol-ecular geometry and the mol-ecular packing is observed at the three temperatures. The morpholinium cation links adjacent chains of anions via N-H⋯O hydrogen bonds, forming a sheet structure parallel to (-111).
Highlights
The asymmetric unit comprises one morpholinium cation and two halves of crystallographically independent bromanilate monoanions, which are located on inversion centres
The refined site-occupancy ratios, which are almost constant in the temperature range studied, are 0.49 (3):0.51 (3), 0.52 (3):0.48 (3) and 0.50 (3):0.50 (3), respectively, at 130, 145 and 180 K, and no significant difference in the molecular geometry and the molecular packing is observed at the three temperatures
We reported the crystal structure of morpholinium hydrogen chloranilate, C4H10NO+C6HCl2O4, in which a short O—H O hydrogen bond is formed between the chloranilate ions and the H atom in the hydrogen bond is disordered over two sites (Ishida & Kashino, 1999)
Summary
Anilic acid (2,5-dihydroxy-1,4-benzoquinone) derivatives, such as chloranilic acid (2,5-dichloro-3,6-dihydroxy-1,4benzoqinone) and bromanilic acid (2,5-dibromo-3,6-dihydroxy-1,4-benzoqinone), appear attractive as a versatile template for generating hydrogen-bonded selfassemblies with various organic bases (Zaman et al, 2001; Molčanov & Kojić-Prodić, 2010; Gotoh & Ishida, 2011; Thomas et al, 2013) and as a model compound for investigating proton dynamics in hydrogen-bond systems (Ikeda et al, 2005; Seliger et al, 2009). We reported the crystal structure of morpholinium hydrogen chloranilate, C4H10NO+C6HCl2O4, in which a short O—H O hydrogen bond is formed between the chloranilate ions and the H atom in the hydrogen bond is disordered over two sites (Ishida & Kashino, 1999). The anomalous behavior was ascribed to a drastic temperature variation of the disordered O—H O doi:10.1107/S2056989015017272. We have undertaken the structural determination of morpholinium hydrogen bromanilate, C4H10NO+C6HBr2O4, to extend the study of hydrogen-bonding in the amine-halohydroxybenzoquinone system.
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