Fig. 7.

Activation enthalpy of ring flips for certain scenarios. a Activation enthalpy of a ring without stabilizing contacts. b Activation enthalpy of a ring with stabilizing contacts, in this case a stacking ring (shown in red). The stabilization of the ground state is between 5 and 10 kJ mol⁻¹ (Burley and Petsko 1989). c Activation enthalpy of a ring with stabilizing contacts of a stacking ring (shown in red), both rings are undergoing concerted ring flips