High-Pressure Freezing, Crystal Structure Studies and Si-CF3 Bond Polarizability of Trimethyl(trifluoromethyl)silane (Postprint)

Abstract

Trimethyl(trifluoromethyl)silane, (CH3)3SiCF3, has been in situ pressure frozen in a diamond anvil cell and its structure determined at 0.90(5) GPa/296 K by single-crystal X-ray diffraction. The crystal is monoclinic, space group P21/m, with the molecules lying on crystallographic mirror planes. The CH3 and CF3 groups assume the fully staggered conformation. The 14-fold coordination scheme of the molecules is similar to those in (CH3)3SiCl polymorphs, but different from that in crystalline tetramethylsilane, (CH3)4Si (TMS). The longest Si-C bond length of 1.943(12) angstrom observed in the crystal structure has been documented. The shortest intermolecular contacts in the structure of pressure-frozen CF3Si(CH3)3 are observed between the hydrogen atoms, and those involving fluorine atoms are longer than sums of van der Waals' radii. These structural features explain the facile cleavage of Si-CF3 bond for CF3 group transfer in organic reactions.

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Document Details

Document Type
Technical Report
Publication Date
Nov 01, 2008
Accession Number
ADA491844

Entities

People

  • Andrzej Katrusiak
  • Anna Olejniczak
  • Ashwani Vij

Organizations

  • Adam Mickiewicz University in Poznań

Tags

Communities of Interest

  • Air Platforms
  • Materials and Manufacturing Processes
  • Space

DTIC Thesaurus Topics

  • Air Force
  • Air Force Research Laboratories
  • Chemical Compounds
  • Chemistry
  • Crystal Lattices
  • Crystal Structure
  • Crystals
  • Diffraction
  • Electron Diffraction
  • Fluorine
  • Halogens
  • High Pressure
  • Measurement
  • Molecules
  • Single Crystals
  • X Rays
  • X-Ray Diffraction

Fields of Study

  • Chemistry

Readers

  • Materials Science and Engineering.
  • Molecular Photonics/Laser Physics

Technology Areas

  • Space