In summary, we have identified blueprints for the design of NHC-CDI adducts that can sample 3D space through isomerization between Z/Z, E/Z, and E/E conformations. The keys to stabilizing E/E conformers are (1) reducing steric crowding between the NHC and CDI N-substituents and (2) installing favorable interactions (e.g., p-stacking) between those same substituents. A new synthetic strategy that leverages the thermodynamic stability of NHC-CDI adducts over NHC dimers was invented to prepare a novel NHC-CDI that adopts an E/E conformation in solution.