Strukturen caesiumhaltiger Fluoride. VII. Cs6Ni5F16 – eine neue Verbindung im System CsF/NiF2 und ihre Kristallstruktur

Structures of Caesium-containing Fluorides. VII. Cs₆Ni₅F₁₆ – a New Compound in the System CsF/NiF₂ and its Crystal Structure Single crystals of a more caesium-containing phase of composition Cs₆Ni₅F₁₆, forming in the course of solid state CsNiF₃ preparation, could be isolated and their structure determined: a = 618.4(1), b = 1. 455.5(2), c = 2145.1(2) pm, space group Cmca, Z = 4, R = 0.030 (1936 independent reflections). The structure contains chains of five face-sharing octahedra, which are connected at their ends via corners to form a zig-zag layer. The Ni? Ni distances within the chains are 264.1 and 270.2 pm, the average Ni? F distance is 202.0 pm. The caesium atoms exhibit 10-, 11-, and 12-coordination. The structural relations to 2L? CsNiF₃ and Cs₄Ni₃F₁₀ are discussed.