Tetra-n-butylammonium bromide: a redetermination at 150 K addressing the merohedral twinning
نویسنده
چکیده
The redetermined, low temperature (150 K), structure of tetra-n-butyl-ammonium bromide, (C(4)H(9))(4)N(+)·Br(-), has been found to be merohedrally twinned via twin law -1 0 0, 0 - 1 0, 1 0 1. The structure was previously determined, with low precision, no inclusion of H atoms and only the bromide ion refined with anisotropic displacement parameters, by Wang et al. (1995 ▶). Mol. Cryst. Liq. Cryst. Sci. Tech. A, 264, 115-129. The redetermined structure has considerably improved precision in all geometrical parameters, has all non-H atoms refined anisotropically, H atoms included, and is isomorphous with the iodide analogue. The structure is otherwise routine, with the shortest cation to anion contacts being between the bromide anion and the CH atoms close to the ammonium nitro-gen centre at a distance of ca. 2.98-3.11 Å. Each anion makes eight such contacts to four different anions. The n-butyl chains are fully extended, adopting an all-anti conformation with approximate S(4) point symmetry.
منابع مشابه
Low-temperature rerefinement of nonmerohedrally twinned tripyridinium bis[tetrabromidoferrate(III)] bromide
The asymmetric unit of the title double salt, (C(5)H(6)N)(3)[FeBr(4)](2)Br, consists of three pyridinium cations, two tetra-hedral bromidoferrate(III) anions and a bromide anion. The three cations each form one N-H⋯Br hydrogen bond to the bromide anion. The crystal under investigation was a non-merohedral twin, with a portion of 22% for the minor twin component.
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