Basicity of (2,6-Pyridino)paracyclophanes: Lone Pair-π, Cation-π, and Solvation Effects

摘要

Polar-π effects often appear to explain the interaction between a π system, such as a benzene ring, and a polar group. Perturbation of the electron density in the benzene ring by systematic "Hammett" substitution leads to reasonable correlations and slopes (p values) consistent with basic teachings of free-energy relationships. In the present study, a simple analysis of the basicity of two (2,11)dithia[3,3](2,6-pyridino)paracycIophanes, one comprising a 2,6-substituted pyridine linked to a 1,4-substituted benzene (1), the other comprising the same pyridine linked to a tetrafluoro cognate of the benzene (2), evokes exactly this analysis and lends additional support to the importance of benzene interactions in determining the stability of cations.