Low symmetry in molecules with heavy peripheral atoms. the gas-phase structure of perfluoro(methylcyclohexane), C6F11CF 3

G.R. Kafka, S.L. Masters, D.A. Wann, H.E. Robertson, D.W.H. Rankin

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When refining structures using gas electron diffraction (GED) data, assumptions are often made in order to reduce the number of required geometrical parameters. Where these relate to light, peripheral atoms there is little effect on the refined heavy-atom structure, which is well defined by the GED data. However, this is not the case when heavier atoms are involved. We have determined the gas-phase structure of perfluoro(methylcyclohexane), C 6F11CF3, using three different refinement methods and have shown that our new method, which makes use of both MP2 and molecular mechanics (MM) calculations to restrain the peripheral-atom geometry, gives a realistic structure without the need for damaging constraints. Only the conformer with the CF3 group in an equatorial position was considered, as ab initio calculations showed this to be 25 kJ mol-1 lower in energy than the axial conformer. Refinements combining both high-level and low-level calculations to give constraints were superior both to those based only on molecular mechanics and to those in which assumptions about the geometry were imposed. © 2010 American Chemical Society.
Original languageUndefined/Unknown
Pages (from-to)11022-11026
Number of pages5
JournalJournal of Physical Chemistry A
Issue number41
Publication statusPublished - 21 Oct 2010

Bibliographical note

Export Date: 1 October 2013

Source: Scopus


doi: 10.1021/jp1077517

Language of Original Document: English

Correspondence Address: Rankin, D. W. H.; School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ, United Kingdom; email: [email protected]

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  • Ab initio calculations
  • Atom structure
  • Equatorial positions
  • Gas electron diffraction
  • Gas-phase structures
  • Geometrical parameters
  • Methylcyclohexane
  • Refinement methods
  • Electron diffraction
  • Geometry
  • Molecular mechanics
  • Petroleum refining
  • Phase structure
  • Refining
  • Atoms

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