Hydrogen motion in proton sponges

Abstract

Hydrogen bonds are an essential concept in chemistry and have been studied extensively by both theoretical and experimental methods. An interesting special case is short strong hydrogen bonds present in proton sponges. In principle, three cases are possible. The potential energy surface (PES) of the hydrogen motion indeed has only one symmetric minimum. Alternatively, there can be two minima separated by a small barrier, such that the proton still moves freely between them even at 0 K. Finally, if the barrier is slightly larger, the proton motion can be frozen at low temperature, but still occurs easily at higher temperature