Ab initio study of the structure of enolic and ketonic forms of ¦Â-diketones with the general formula R¡åCOCH₂COR?(R?and R?= H, CH₃, CF₃)

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• 作者：V. V. Sliznev ; S. B. Lapshina and G. V. Girichev
• 关键词：β ; diketones ; enol ; ketone ; quantum chemical computations ; structure ; vibration analysis ; potential function ; conformers ; intramolecular hydrogen bond
• 刊名：Journal of Structural Chemistry
• 出版年：2006
• 出版时间：March, 2006
• 年：2006
• 卷：47
• 期：2
• 页码：220-231
• 全文大小：164 KB

文摘

Geometric parameters, values of force constants and vibration frequencies for different geometric configurations of enolic and ketonic forms of molecules of β-diketones, R″COCH₂COR′ (R″ and/or R′ are H, CH₃, CF₃) have been computed by the ab initio method MO LCAO SCF using wide bases of Cartesian Gaussians. The enolic form of the considered molecules is most energetically favorable. Values of isomerization energy, the height of internal rotation barriers, and energies of the intramolecular hydrogen bond were obtained for it. The stabilization of the enolic form was shown to be caused by the presence of the intramolecular hydrogen bond in the chelate ring. The effect of a substituent on the computed values of molecular parameters was examined. The comparison with the available experimental data testifies to a sufficiently high reliability of the data obtained.