9‐Br‐closo‐1,2‐C₂B₁₀H₁₁ has been prepared and its gas‐phase structure has been examined by means of gas electron diffraction. The structure of the carbaborane core is similar to the structure of the parent compound, which is of C_2v symmetry. A DFT‐based search for the corresponding reaction pathway of the bromination of closo‐1,2‐C₂B₁₀H₁₂ revealed that the catalytic amount of aluminum reduces the barrier of the initial attack of the bromination agent toward the negatively charged part of the icosahedral carbaborane, i. e., the first transition state, from about 40 to about 27 kcalmol^‐1. The Br−Br bond is weakened by an intermediate binding to the large π‐hole on the aluminum atom of AlBr₃, which is the driving force for the AlBr₃‐catalyzed bromination.

中文翻译：

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气态电子衍射法确定closo-1,2-C2B10H12的溴化机理和生成的9-Br-closo-1,2-C2B10H11的结构

制备了9-溴-1,2-C ₂ B ₁₀ H _11，并通过气相电子衍射检查了其气相结构。碳硼烷核的结构与母体化合物的结构相似，具有C _2v对称性。基于DFT的closo - _1,2 -C ₂ B ₁₀ H ₁₂溴化反应的相应反应路径研究表明，催化量的铝减少了溴化剂最初攻击溴代甲烷负电荷部分的障碍。二十面体碳硼烷 例如，第一过渡态，从大约40 kcalmol到大约27 kcalmol^‐1。Br-Br键通过与AlBr ₃铝原子上大π孔的中间键而减弱，这是AlBr ₃催化溴化的驱动力。