Abstract The cesium dodecahydro-monocarba-closo-dodecaborate Cs[CB11H12] crystallizes with an unexpected trigonal crystal structure having the lattice parameters a = 2094.73(3) and c = 1324.56(2) pm (c/a = 0.632) for Z = 18. The non-centrosymmetric space group R3 allows an ordering of the unsymmetric [CB11H12]– anions in a way that the least electronegative vertices of the pseudo-icosahedral cages avoid close proximity to the Cs+ cations. Hence there are channels at [0 0 z], [1/3 2/3 z] and [2/3 1/3 z], into which the C–H bonds of the [CB11H12]– units are pointing. There are two crystallographically independent Cs+ cations and [CB11H12]– anions present with unsurprising interatomic distances (d(C–B) = 166–181 pm, d(B–B) = 170–183 pm, d(B–H) = d(C–H) ≈ 110 pm) for the latter. Both Cs+ cations have contact to 18 hydrogen atoms (d(Cs–H) = 296–427 pm) stemming from six unevenly face-grafting [CB11H12]– anions, where only B–H bonds are involved. This fact is nicely reflected by IR and Raman spectroscopy. According to a 6/6 motif of the ions with highly distorted mutual octahedral coordination spheres of their centres of gravity, the crystal structure of Cs[CB11H12] follows roughly a rock salt-like arrangement. This becomes even more evident, when order-disorder transitions starting at T = 60 °C lead to more highly symmetrical structures with orientationally disordered [CB11H12]– anions.

中文翻译：

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Die unerwartete Kristallstruktur des Csium-Dodekahydro-Monocarba-closo-Dodekaborats Cs[CB11H12]

摘要 十二氢-单碳-闭-十二硼酸铯 Cs[CB11H12] 以意外的三角晶体结构结晶，晶格参数为 a = 2094.73(3) 和 c = 1324.56(2) pm (c/a = 0.632)，Z = 18 . 非中心对称空间群 R3 允许对非对称 [CB11H12]– 阴离子进行排序，从而使伪二十面体笼的电负性最小的顶点避免靠近 Cs+ 阳离子。因此在[0 0 z]、[1/3 2/3 z]和[2/3 1/3 z]处有通道，[CB11H12]-单元的C-H键指向这些通道。有两种晶体学独立的 Cs+ 阳离子和 [CB11H12]– 阴离子，其原子间距离并不奇怪（d(C–B) = 166–181 pm，d(B–B) = 170–183 pm，d(B–H) =对于后者，d(C–H) ≈ 110 pm)。两种 Cs+ 阳离子都与 18 个氢原子 (d(Cs–H) = 296–427 pm) 接触，这些氢原子源自六个不均匀的面接枝 [CB11H12]– 阴离子，其中仅涉及 B–H 键。IR 和拉曼光谱很好地反映了这一事实。根据重心高度扭曲的相互八面体配位球的离子的 6/6 基序，Cs[CB11H12] 的晶体结构大致遵循岩盐状排列。这变得更加明显，当从 T = 60 °C 开始的有序-无序转变导致具有取向无序的 [CB11H12]– 阴离子的高度对称结构时。根据重心高度扭曲的相互八面体配位球的离子的 6/6 基序，Cs[CB11H12] 的晶体结构大致遵循岩盐状排列。这变得更加明显，当从 T = 60 °C 开始的有序-无序转变导致具有取向无序的 [CB11H12]– 阴离子的高度对称结构时。根据重心高度扭曲的相互八面体配位球的离子的 6/6 基序，Cs[CB11H12] 的晶体结构大致遵循岩盐状排列。这变得更加明显，当从 T = 60 °C 开始的有序-无序转变导致具有取向无序的 [CB11H12]– 阴离子的高度对称结构时。