Synthese und Kristallstruktur von Cadmium‐Dodekahydro‐ closo ‐Dodekaborat‐Hexahydrat, Cd(H 2 O) 6 [B 12 H 12 ]

Synthesis and Crystal Structure of Cadmium Dodecahydro closo ‐Dodecaborate Hexahydrate, Cd(H 2 O) 6 [B 12 H 12 ] Through neutralization of the aqueous free acid (H 3 O) 2 [B 12 H 12 ] with cadmium carbonate (CdCO 3 ) and after isothermic evaporation of the resulting solution, colourless lath‐shaped single crystals of Cd(H 2 O) 6 [B 12 H 12 ] are obtained. Cadmium dodecahydro closo ‐dodecaborate hexahydrate crystallizes at room temperature in the monoclinic system (space group: C2/m) with the lattice constants a = 1413.42(9), b = 1439.57(9), c = 749.21(5) pm and β = 97.232(4)° (Z = 4). The crystal structure of Cd(H 2 O) 6 [B 12 H 12 ] can be regarded as a monoclinic distortion variant of the CsCl‐type structure. Two crystallographically different [Cd(H 2 O) 6 ] 2+ octahedra (d(Cd–O) = 227–230 pm) are present which only differ in their relative orientation. The intramolecular bond lengths for the quasi ‐icosahedral [B 12 H 12 ] 2− cluster anions range in the intervals usually found for dodecahydro closo ‐dodecaborates (d(B–B) = 177–179 pm, d(B–H) = 103–116 pm). The hydrogen atoms of the [B 12 H 12 ] 2− clusters have no direct coordinative influence on the Cd 2+ cations. Due to the fact that no “zeolitic” crystal water molecules are present, a stabilization of the lattice takes place mainly via the B–H δ− ··· +δ H–O hydrogen bonds.