Accurate Gas-Phase Experimental Structures of Octasilsesquioxanes (Si8O12X8; X = H, Me)

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• 作者：Derek A. Wann ; Robert J. Less ; Franck Rataboul ; Philip D. McCaffrey ; Anthony M. Reilly ; Heather E. Robertson ; Paul D. Lickiss ; David W. H. Rankin
• 刊名：Organometallics
• 出版年：2008
• 出版时间：August 25, 2008
• 年：2008
• 卷：27
• 期：16
• 页码：4183-4187
• 全文大小：173K
• 年卷期：v.27,no.16(August 25, 2008)
• ISSN：1520-6041

文摘

The accurate structures of silsesquioxanes Si₈O₁₂H₈ and Si₈O₁₂Me₈ have been determined by gas-phase electron diffraction methods in order to obtain experimental data on single molecules unconstrained by a crystal lattice for comparison with data obtained by theoretical methods. For Si₈O₁₂H₈ the experimentally determined structure shows ideal O_h symmetry with Si−O distances and Si−O−Si angles of 161.41(3) pm and 147.9(2)° [r_e, uncertainties (σ) in parentheses] compared with 162.9 pm and 147.8° for theoretical results from MP2/6-311++G(3df,3pd) calculations. In Si₈O₁₂Me₈ a similar O_h symmetry model gave experimental values of 161.74(5) pm and 148.9(2)° for the Si−O distances and Si−O−Si angles compared with calculated values of 163.2 pm and 148.6°, respectively.