Gas-phase structures of sterically crowded disilanes studied by electron diffraction and quantum chemical methods: 1,1,2,2-tetrakis(trimethylsilyl)disilane and 1,1,2,2-tetrakis(trimethylsilyl) dimethyldisilane

Jan Schwabedissen, Paul D. Lane, Sarah L. Masters, Karl Hassler, Derek A. Wann

Research output: Contribution to journalArticle

Abstract

The gas-phase structures of the disilanes 1,1,2,2-tetrakis(trimethylsilyl)disilane [(Me3Si)(2)HSiSiH(SiMe3)(2)] (1) and 1,1,2,2-tetrakis(trimethylsilyl)dimethyldisilane [(Me3Si)(2)MeSiSiMe(SiMe3)(2)] (2) have been determined by density functional theoretical calculations and by gas electron diffraction (GED) employing the SARACEN method. For each of 1 and 2 DFT calculations revealed four C-2-symmetric conformers occupying minima on the respective potential-energy surfaces; three conformers were estimated to be present in sufficient quantities to be taken into account when fitting the GED data. For (Me3Si)(2)RSiSiR(SiMe3)(2) [R = H (1), CH3 (2)] the lowest energy conformers were found by GED to have RSiSiR dihedral angles of 87.7(17)degrees for 1 and -47.0(6)degrees for 2. For each of 1 and 2 the presence of bulky and flexible trimethylsilyl groups dictates many aspects of the geometric structures in the gas phase, with the molecules often adopting structures that reduce steric strain.

Original languageEnglish
Pages (from-to)10175-10182
Number of pages8
JournalDalton Transactions
Volume43
Issue number26
DOIs
Publication statusPublished - 14 Jul 2014

Keywords

  • AB-INITIO CALCULATIONS
  • MOLECULAR-ORBITAL METHODS
  • VALENCE BASIS-SETS
  • CONFORMATIONAL COMPOSITION
  • VIBRATIONAL-SPECTRA
  • DENSITY
  • TETRASILANES
  • HEXASILANES
  • ELEMENTS

Cite this