Darstellung und Kristallstrukturen von Dipyridiniomethan-Monohalogenohydro-closo-Dodecaboraten(2−), [(C5H5N)2CH2][B12H11X]; X = Cl,Br, I

Preparation and Crystal Structures of Dipyridiniomethane Monohalogenohydro-closo-Dodecaborates(2?), (C₅H₅N)₂CH₂]B₁₂H₁₁X]; X = Cl, Br, I B₁₂H₁₂]^2? reacts with dihalogenomethanes CH₂X₂ in presence of trifluoro acetic acid, yielding the monohalogenododecaborates B₁₂H₁₁X]^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 (C₅H₅N)₂CH₂]B₁₂H₁₁Cl] · 2(CH₃)₂SO (orthorhombic, space group Pnma, a = 17.351(6), b = 16.034(5), c = 9.659(2) Å, Z = 4) and of the isotypic bromo and iodo compounds (C₅H₅N)₂CH₂]B₁₂H₁₁X] (monoclinic, space group P2₁/n, Z = 4; for X = Br: a = 7.339(2), b = 15.275(3), c = 16.761(4) Å, β = 96.80(2)°; for X = I: a = 7.4436(8), b = 15.3510(8), c = 16.9213(16) Å, ß = 97.326(7)°) exhibit crystal lattices build up by columns of substituted boron clusters and angular dications (C₅H₅N)₂CH₂]²⁺ orientated along the shortest axis which are assembled to alternating layers.