title: Characterization and Reactivity of the [N,N-Dimethyl(thioformamidyl)]-9-fluorenyl Cation(1).
abstract: The 9-[N,N-dimethyl(thioformamidyl)]-9-fluorenyl cation was generated under stable ion conditions and characterized by UV/visible and NMR spectroscopy and methanol trapping reactions. The same cation was generated by laser excitation of the appropriate chloride precursor in 2,2,2-trifluoroethanol, and rate constants for nucleophilic quenching by alcohols and several anions were measured. The quenching data for this and other 9-fluorenyl cations demonstrate that the reactivity decreases for 9-substituents in the order H > carbomethoxy > N,N-dimethyl(thioformamidyl), demonstrating that the thioamidyl group imparts substantial kinetic stabilization to an adjacent cationic center. Both steric and electronic factors are suggested to be important in determining this reactivity order.
authors.affiliation: Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, Ontario, Canada K1A 0R6, and Department of Chemistry, York University, North York, Ontario, Canada M3J 1P3.
authors.forename: Calvin S. Q.
authors.initials: CS
authors.lastname: Lew
authors.forename: David F.
authors.initials: DF
authors.lastname: Wong
authors.forename: Linda J.
authors.initials: LJ
authors.lastname: Johnston
authors.forename: Michael
authors.initials: M
authors.lastname: Bertone
authors.forename: Alan C.
authors.initials: AC
authors.lastname: Hopkinson
authors.forename: Edward
authors.initials: E
authors.lastname: Lee-Ruff