Conformational Behaviors of 2-Substituted Cyclohexanone Oximes: An AB Initio,Hybrid Dft Study,and NBO Interpretation |
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Authors: | Fatemeh Azarakhshi Davood Nori-Shargh Nasrin Masnabadi Hooriye Yahyaei Seiedeh Negar Mousavi |
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Affiliation: | 1. Department of Chemistry , Arak Branch, Islamic Azad University , Arak , Iran;2. Department of Chemistry, Zanjan Branch , Islamic Azad University , Zanjan , Iran |
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Abstract: | Abstract The impacts of the generalized anomeric effect (GAE) and gauche effect (GE) associated with donor–acceptor electron delocalizations and dipole–dipole interactions on the conformational properties of 2-methoxy- (1), 2-methylthio- (2), 2-methylseleno- (3), 2-fluoro- (4), 2-chloro- (5), and 2-bromocyclohexanone oxime (6) have been studied by means of hybrid density functional theory (B3LYP/6–311+G**) and ab initio molecular orbital (HF/6–311+G**)-based methods and natural bond orbital (NBO) interpretation. Both methods used showed that the above compounds exist predominantly in the axial chair conformation and the axial conformation stability increased from 2-methoxy- (1) to 2-methylselenocyclohexanone oxime (3) and also from 2-fluoro- (4) to 2-bromocyclohexanone oxime (6). The NBO analysis showed that the GAE increases from compound 1 to compound 3 and also from compound 4 to compound 6. GE does not have significant impact on the conformational behaviors of compounds 1–6 and GAE succeeds in accounting qualitatively for the increase of the axial preferences in both series of compounds. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Table S1. Supporting Information Available. The structures optimized and thermodynamic functions of the axial and equatorial conformations of compounds 1–6. This material is available free of charge via the Internet. |
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Keywords: | ab initio Generalized anomeric effects NBO 2-substituted cyclohexanone oximes |
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