Quantum Chemical Study of Spatial Structure and Stereoelectronic Properties of Iminodihydrofuran Ensembles

A quantum chemical study of structural peculiarities of iminodihydrofuran ensembles (from dimers to tetramers with individual calculations for penta- and hexamers) associated with their rotation isomerism was carried out. Three basic spatial packings of the iminodihydrofuran chains were distinguished with increasing the number of ensemble elements. The spiral and linear packings are equally probable from the standpoint of their thermodynamic stability. The third packing, exhibiting the curvature radius, is inferior to the former two, as judged from the relative stability. It was shown that ensembles in the alternating linear-spiral form are fundamentally possible to exist. Data was obtained testifying to a possibility for the intramolecular hydrogen bond forming between the imine and amine moieties in the tetramer spiral structures; activation barriers of intramolecular prototropic rearrangement were determined.