Surfing pi Clouds for Noncovalent Interactions: Arenes versus Alkenes

摘要

A comparative study of molecular balances by NMR spectroscopy indicates that noncovalent functional-group interactions with an arene dominate over those with an alkene, and that a -facial intramolecular hydrogen bond from a hydroxy group to an arene is favored by approximately 1.2kJmol(-1). The strongest interaction observed in this study was with the cyano group. Analysis of the series of groups CH2CH3, CHCH2, CCH, and CN shows a correlation between conformational free-energy differences and the calculated charge on the C atom of these substituents, which is indicative of the electrostatic nature of their interactions. Changes in the free-energy differences of conformers show a linear dependence on the solvent hydrogen bond acceptor parameter .