title: Evidence for beta-chlorocarbenium and beta-bromocarbenium ions.
abstract: Isotopic perturbation of degenerate equilibrium is used to determine whether tetramethylethylenechloronium and tetramethylethylenebromonium ions are closed 1,2-bridged structures or rapid equilibria of open beta-halocarbenium ions. The observed 13C NMR isotope shifts are consistent with a combination of large equilibrium shifts and small upfield intrinsic shifts. The presence of equilibrium shifts in both halonium ions indicates that these ions are not closed 1,2-bridged structures. Rather, they are best represented by equilibria of beta-halocarbenium ions.
authors.affiliation: Department of Chemistry, Villanova University, Villanova, Pennsylvania 19085, USA. brian.ohta@villanova.edu
authors.forename: Brian K
authors.initials: BK
authors.lastname: Ohta
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Hough
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Schubert