title: Nonamethylcyclopentyl cation rearrangement mysteries solved.
abstract: The C1 nonamethylcyclopentyl cation minimum undergoes complete methyl scrambling in SbF5 with a 7 kcal/mol barrier. This corresponds to the rate-limiting conformational interconversion of enantiomeric hyperconjomers via a C(s) transition structure (above right). A remarkable, more rapid, second process only exchanges methyls within sets of four and five (blue and red, see above), as has been observed experimentally at low temperatures. The computed ∼2 kcal/mol barrier involves a C(s) [1s,2s] sigmatropic methyl shift transition structure (above left).
authors.affiliation: Department of Chemistry, University of California-Davis, 1 Shields Avenue, Davis, California 95616, United States. djtantillo@ucdavis.edu
authors.forename: Dean J
authors.initials: DJ
authors.lastname: Tantillo
authors.forename: Paul von Ragué
authors.initials: Pv
authors.lastname: Schleyer