Influence of Antipodally Coupled Iodine and Carbon Atoms on the Cage Structure of 9,12-I2-closo-1,2-C2B10H10: An Electron Diffraction and Computational Study

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• 作者：Yury V. Vishnevskiy ; Denis S. Tikhonov ; Christian G. Reuter ; Norbert W. Mitzel ; Drahom铆r Hnyk ; Josef Holub ; Derek A. Wann ; Paul D. Lane ; Raphael J. F. Berger ; Stuart A. Hayes
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：December 21, 2015
• 年：2015
• 卷：54
• 期：24
• 页码：11868-11874
• 全文大小：392K
• ISSN：1520-510X

文摘

Because of the comparable electron scattering abilities of carbon and boron, the electron diffraction structure of the C_2v-symmetric molecule closo-1,2-C₂B₁₀H₁₂ (1), one of the building blocks of boron cluster chemistry, is not as accurate as it could be. On that basis, we have prepared the known diiodo derivative of 1, 9,12-I₂-closo-1,2-C₂B₁₀H₁₀ (2), which has the same point-group symmetry as 1 but in which the presence of iodine atoms, with their much stronger ability to scatter electrons, ensures much better structural characterization of the C₂B₁₀ icosahedral core. Furthermore, the influence on the C₂B₁₀ geometry in 2 of the antipodally positioned iodine substituents with respect to both carbon atoms has been examined using the concerted application of gas electron diffraction and quantum chemical calculations at the MP2 and density functional theory (DFT) levels. The experimental and computed molecular geometries are in good overall agreement. Molecular dynamics simulations used to obtain vibrational parameters, which are needed for analyzing the electron diffraction data, have been performed for the first time for this class of compound. According to DFT calculations at the ZORA-SO/BP86 level, the ¹¹B chemical shifts of the boron atoms to which the iodine substituents are bonded are dominated by spin鈥搊rbit coupling. Magnetically induced currents within 2 have been calculated and compared to those for [B₁₂H₁₂]^{2鈥?/sup>, the latter adopting a regular icosahedral structure with I_h point-group symmetry. Similar total current strengths are found but with a certain anisotropy, suggesting that spherical aromaticity is present; electron delocalization in the plane of the hetero atoms in 2 is slightly hindered compared to that for [B₁₂H₁₂]2鈥?/sup>, presumably because of the departure from ideal icosahedral symmetry.}