β-NbBr5, eine neue Modifikation von Niobpentabromid mit einer eindimensionalen Lagenfehlordnung/ β-NbBr5, a New Modification of Niobium Pentabromide Having One-Dimensional Stacking Disorder

Müller, Ulrich; Klingelhöfer, Paul

β-NbBr5, eine neue Modifikation von Niobpentabromid mit einer eindimensionalen Lagenfehlordnung/ β-NbBr5, a New Modification of Niobium Pentabromide Having One-Dimensional Stacking Disorder

2014

Müller, Ulrich | Klingelhöfer, Paul

While trying to react NbBr₅ with sulfur in a closed tube, crystals of the new modification β-NbBr₅ were obtained. Its X-ray diffraction patterns have sharp reflexions and diffuse streaks showing the presence of a one-dimensional disorder. From the sharp reflexions alone, a statistically averaged sub-structure results; it has the space group Ccmm and the lattice constants a₀ = 644, b₀ = 1867 and c₀ = 615 pm. Taking into account the diffuse streaks, the true structure was deduced; its lattice constants are a = 2a₀, c = Co, b indefinite due to the disorder. β-NbBr₅ is isostructural to tantalum pentaiodide. It consists of layers of (NbBr₅)₂ molecules that are stacked with displacement faults in the direction of b. The bromine atoms have a hexagonal close-packing arrangement.

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