Bartell mechanism

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. The mechanism exchanges the axial atoms with one pair of the equatorial atoms. Similarly to the Berry mechanism in square planar molecules, the symmetry of the intermediary phase of the vibrational mode is "chimeric"cite web|url=http://www.ch.ic.ac.uk/rzepa/bpr/ |publisher=ch.ic.ac.uk |title=Mechanisms that Interchange Axial and Equatorial Atoms in Fluxional processes |accessdate=2008-01-22] 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

ee also

*Berry mechanism
*Pseudorotation