Metalloktaederdoppel in den Clusterverbindungen Gd10I16(C2)2 und Gd10Br15B2/Tb10Br15B2

Gd₁₀I₁₆(C₂)₂ and Gd₁₀Br₁₅B₂/Tb₁₀Br₁₅B₂ Cluster Compounds with M₁₀ Twin Octahedra The compound Gd₁₀I₁₆(C₂)₂ can be prepared from Gd metal, GdI₃ and C at 950 °C. It crystallizes in P1 with a = 10.463(4) Å, b = 16.945(6) Å, c = 11.220(4) Å, α = 99.15(3)°, β = 92.68(3)° und γ = 88.06(3)°. Gd₁₀Br₁₅B₂ is formed between 900 und 950 °C, Tb₁₀Br₁₅B₂ between 900 und 930 °C from stoichiometric amounts of the rare earth metals, tribromide and boron. Both compounds crystallize in the space group P1 for Gd₁₀Br₁₅B₂ with a = 8.984(2) Å, b = 9.816(2) Å, c = 10.552(5) Å, α = 91.14(3)°, β = 114.61(3)° and γ = 110.94(3)° and for Tb₁₀Br₁₅B₂ with a = 8.939(4) Å, b = 9.788(3) Å, c = 10.502(2) Å, α = 91.19(3)°, β = 114.51(3)° and γ = 111.10(2)°. In the crystal structures of all three compounds the rare earth metals form edge‐shared Ln₁₀ twin octahedra. In Gd₁₀I₁₆(C₂)₂ the Gd octahedra are centered with C₂ groups (d_C–C = 1.43(7) Å). In Ln₁₀Br₁₅B₂ (Ln = Gd, Tb) the octahedra contain single boron atoms. The clusters are connected through halide atoms to chains Ln₁₀(Z)₂X X X ]. Adjacent chains are fused threedimensionally via I I for the Gd iodide carbide and via Br Br for the bromide borides of Gd und Tb. It is interesting to see an identical pattern of connection between the chains for the reduced oxomolybdates, e. g. PbMo₅O₈.