THEORETICAL ENERGY GRADIENT STUDY OF FIVE - MEMBERED RINGS
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Date
1977
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
An energy gradient procedure is combined with extended H\""{u}ckel molecular orbital theory to study the conformations of seven 5-membered ring molecules. The potential energy and pucker amplitude are determined as functions of the pseudorotation angle. Two of the molecules are analogs of nucleic acid sugars. The deoxyribose sugar analog has a single global minimum and a high barrier (3.4 kcal/mol) to pseudorotation. The ribose analog has two global minima with a high barrier (2.7 kcal/mol) between them in one direction and a low barrier (0.5 kcal/mol) between them in the other direction along the pseudorotation path. The high barriers are found only when both $NH_{2}$ and $CH_{3}$ exocyclic substituents are present. Comparisons are made with results from experiment and from earlier gradient calculations on cyclopentane, cyclopentanol, and tetrahydrofuran.
Description
Author Institution: Department of Physics and Astronomy, The University of New Mexico