Intermolecular Hydrogen Bonding in Noncovalent Complexes of Cavitands Studied by Gas-Phase Ion-Molecule Reactions and Theoretical Calculations

摘要

Interaction of the primary alkyl ammonium ions with the cavitands resembles a gyroscope (Fig. 5a), which leaves at least one hydrogen at a time open for reaction. In the secondary ammonium complexes of 2 and 4, both NH protons are involved in hydrogen bonding with adjacent P(velence)O groups and exchange reactions are not observed (Fig. 5b). Cavitands 1 and 3 can effectively employ only a single available hydrogen bonding site and the interaction with a secondary ammonium ion is reminiscent of a pendulum, which enables the occurence of reactions (Fig 5d). Also the tertiary ammonium complex of 2 resembles a pendulum (Fig. 5c), but with 1 and 3, tertiary ammonium ions form a stable hydrogen bond.