Autori: C. Uncuta, E. Bartha, D. Gherase, I.A. Loas, F. Teodorescu, R. A. Varga, N. Vanthuyne, C. Roussel, U. Berg

Editorial: J.Mol.Struc., p.989, 2011.

Rezumat:

A homologous series of chiral bis-ketals and mixed hemiketal-ketals with rigid bicyclo[3.3.1]-3,7-dioxanonane skeleton has been prepared. The crystallization mode (conglomerate or racemic compound) was established by chiral HPLC with double UV/polarimetric detection. The study of the solid-state structure by single crystal X-ray diffraction disclosed interesting CHcdots, three dots, centeredπ intermolecular interactions. Hindering of rotation of phenyl groups at (hemi)ketalic centres was found to occur. A 1H–DNMR study gave activation barriers ΔG# of 15.9 kcal mol−1 in the ketalic moiety and 10.3 kcal mol−1 in the hemiketalic moiety. The experimental results were substantiated by MM and DFT calculations for ground and transition states.

Cuvinte cheie: X-ray analyses, Conglomerate, CH-Pi, interactions, DNMR, Hindered rotation barriers, DFT calculations

URL: http://dx.doi.org/10.1016/j.molstruc.2010.12.028