The Subbromide Bi5Br4 – On the Existence of a Hidden Phase |
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| Authors: | Falk Pabst Jen-Hui Chang Kati Finzel Miroslav Kohout Peer Schmidt Michael Ruck |
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| Institution: | 1. Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062 Dresden, Germany;2. Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany;3. Brandenburgische Technische Universität Cottbus Senftenberg, Universitätsplatz 1, 01968 Senftenberg, Germany |
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| Abstract: | Black and irregularly shaped crystals of the bismuth-rich bromide Bi5Br4 were obtained as a by-product of the reaction of CsBr, Bi, and BiBr3. X-ray diffraction on a single-crystal revealed its orthorhombic structure with the space group Pmmn (no. 59) and lattice parameters a = 1800.0(2) pm, b = 1476.1(1) pm, and c = 924.5(2) pm at 296 K. The structure is composed of Bi82+ and Bi95+ polycations and bromidobismuthate(III) anions according to the structured formula Bi5Br4 = Bi20Br16 = Bi82+Bi95+BiBr5]2–Bi2Br11]5–. Bi5Br4 is the bismuth-richest among the bismuth subhalides containing isolated polycations. Extensive differential scanning calorimetry studies indicate that Bi5Br4 decomposes at 262 °C, i.e. one degree below the bismuth-rich eutectic at 263 °C. All attempts towards a rational synthesis yielded predominantly the neighboring phases BiBr and Bi6Br7. |
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| Keywords: | Bromine Bismuth Cluster compounds Phase diagrams Polycations |
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