6-Phenyl-1,5-diazabicyclo[3.1.0]hexane: structure variations going from gas to crystal phase

Based on gas electron diffraction experiments supported by quantum chemical simulations, the molecular structure of 6-phenyl-1,5-diazabicyclo[3.1.0]hexane (PhDBH) in the gas phase was determined, which is characterized by the puckering motion of the five-membered ring typical of bicyclo[3.1.0]- hexanes. It was found that the previously determined crystal packing is accompanied by a certain torsional twisting of the molecule, requiring activation energy. Based on the simulations of PhDBH clusters, it was shown that the energy is compensated by intermolecular interactions.