Zur Polymorphie von In5Br7 |
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Authors: | Michael Ruck,Hartmut Bä rnighausen |
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Abstract: | On the Polymorphism of In5Br7 The existence of two polymorphs of In5Br7 has been proved by single crystal structure determinations. In5Br7 (tP192) crystallizes with the tetragonal space group P41212 and lattice parameters at = 1318.9(5) pm and ct = 3723.8(9) pm (293 K). Concerning monoclinic In5Br7 (mC192), the centrosymmetric space group C2/c with lattice parameters am = 1867.3(4) pm, bm=1867.0(5) pm, cm = 1918.0(7) pm, and βm = 103.96(2)° (293 K) has been confirmed. Both modifications of In5Br7 are built up from layers of the same type. These layers with a thickness of about 930 pm consist of structure fragments [InBr2]4+ and [InBr12]4–. The anion is composed of two ethan‐like [InBr6]2– units, which contain In–In bonds. The stacking sequence of the layers with symmetry C 1 2 (1) differs for the two modifications of In5Br7. The tetragonal form is generated by applying a 41 screw axis; the monoclinic polymorph is formed by introducing inversion centers between the layers. The adequate name of In5Br7 = In[InBr6]Br is triindium(I)‐hexabromodiindate(II)(In–In)‐bromide. |
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Keywords: | Indium bromide crystal structure polymorphism pseudo‐symmetry twinning stacking faults |
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