Bartell mechanism

The pentagonal bipyramidal molecular geometry, on which the Bartell pseudorotation acts

The Bartell mechanism is a pseudorotational mechanism similar to the Berry mechanism. It occurs only in molecules with a pentagonal bipyramidal molecular geometry, such as IF7. This mechanism was first predicted by H. B. Bartell in 1970.[1] The mechanism exchanges the axial atoms with one pair of the equatorial atoms with an energy requirement of about 2.7 kcal/mol. Similarly to the Berry mechanism in square planar molecules, the symmetry of the intermediary phase of the vibrational mode is "chimeric"[1][2][3] of other mechanisms; it displays characteristics of the Berry mechanism, a "lever" mechanism seen in pseudorotation of disphenoidal molecules, and a "turnstile" mechanism (which can be seen in trigonal bipyramidal molecules under certain conditions).

References

  1. 1 2 WJ Adams, HB Thompson, LS Bartell, 1970, J. Chem. Phys. 53:4040-6.
  2. ↑ LS Bartell, MJ Rothman & A Gavezzotti, 1982, J. Chem. Phys. 76:4136-4413.
  3. ↑ M Cass, KK Hii & HS Rzepa, 2005, "Mechanisms that interchange axial and equatorial atoms in fluxional processes: Illustration of the Berry pseudorotation, the turnstile and the lever mechanisms via animation of transition state normal vibrational modes", J. Chem. Educ. (online), 2005; see Archived 2019-10-19 at the Wayback Machine, accessed 28 May 2014

See also


This page is issued from Wikipedia. The text is available under Creative Commons Attribution-Share Alike 4.0 unless otherwise noted. Additional terms may apply for the media files.