Kristallstruktur von Dipyridiniomethan-Monohalogenohydro-closo-Decaboraten(2–), [(C5H5N)2CH2][2-XB10H9]; X  Cl,Br, I

Crystal Structures of Dipyridiniomethane Monohalogenohydro-closo-Decaborates(2–), (C₅H₅N)₂CH₂]2-XB₁₀H₉]; X = Cl, Br, I B₁₀H₁₀]^2? reacts with chlorine, bromine and iodine or with N-halogenosuccinimide, yielding the monohalogenodecaborates 2-XB₁₀H₉]^2? (X = Cl, Br, I), which are separated by ion exchange chromatography on diethylaminoethyl(DEAE) cellulose from the starting compound and higher halogenated products. The X-ray structure determinations of the isotypic chloro and bromo compounds (C₅H₅N)₂CH₂]2-XB₁₀H₉] (monoclinic, space group C2/c, Z = 8; for X ? Cl: a = 33.174(5), b = 7.2809(4), c = 16.2232(7) Å, β = 113.307(7)°; for X = Br: a = 33.525(11), b = 7.281(2), c = 16.297(4) Å, β = 113.62(2)°) and of the iodo compound (C₅H₅N)₂CH₂]2-IB₁₀H₉] (monoclinic, space group P2₁, Z = 2, a = 7.143(3), b = 13.568(4), c = 9.479(7) Å, β = 97.57(5)°) show columns of substituted boron clusters 2-XB₁₀H₉]^2?, X = Cl, Br, I and bent dications (C₅H₅N)₂CH₂]²⁺ along the shortest axis wich are assembled to alternating layers in the crystal lattice.