Singularities in Molecular Conformation

Authors:

• Szymon Sobczak,
• Andrzej Katrusiak

Abstract

The intramolecular coupling between molecular groups leads to singularities in the molecular conformation, acting like a switch in a molecular-scale rotor. This, in turn, affects the potential-energy (E_p) barriers, acquiring a sharp shape originating from superimposed E_p functions of the molecular conformers with differently coupled methyl groups. The molecular conformation fixed at the switching position results in the disordered methyl orientations in the crystalline state. These general features have been observed for the molecule of pinacolone. The structure of the pinacolone crystals frozen at low-temperature isobaric and high-pressure isochoric conditions has been determined.