Accurate gas-phase experimental structures of octasilsesquioxanes (Si8O12X8; X = H, Me)

Derek A. Wann, Robert J. Less, Franck Rataboul, Philip D. McCaffrey, Anthony M. Reilly, Heather E. Robertson, Paul D. Lickiss, David W. H. Rankin

Research output: Contribution to journalArticlepeer-review

Abstract

The accurate structures of silsesquioxanes Si8O12H8 and S8O12Me8 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 Oh, symmetry with Si-O distances and Si-O-Si angles of 161.41(3) pm and 147.9(2)° [re, 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 Oh 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.

Original languageEnglish
Pages (from-to)4183-4187
Number of pages5
JournalOrganometallics
Volume27
DOIs
Publication statusPublished - 2008

Keywords

  • POLYHEDRAL OLIGOMERIC SILSESQUIOXANES
  • MOLECULAR-ORBITAL METHODS
  • VALENCE BASIS-SETS
  • AB-INITIO
  • POLYMER NANOCOMPOSITES
  • ELECTRON-DIFFRACTION
  • CUBIC SILSESQUIOXANE
  • POSS NANOCOMPOSITES
  • CRYSTALLINE PHASES
  • 2ND-ROW ELEMENTS

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