Internal Rotation in Aldehydes Containing Four-Membered Rings

The paper presents the results of a theoretical analysis of the low-frequency region of the vibrational spectrum and calculations of the internal rotation of model molecules containing a four-membered carbocyclic fragment and a CHO formyl group bonded with it in the anharmonic approximation. The influence of the form of the potential energy surface (PES) and the behavior of kinematic factors on the values of torsion frequencies is considered. The possibility of a pronounced kinematic relationship between the internal rotation and other low-frequency modes is examined.