Ab initio study of the structure of enolic and ketonic forms of β-diketones with the general formula R″COCH2COR′ (R′ and R″ = H, CH3, CF3).

Autor:	Sliznev, V. V., Lapshina, S. B., Girichev, G. V.
Předmět:	KETONES GEOMETRIC quantization VIBRATIONAL spectra ISOMERIZATION HYDROGEN bonding CHELATES MOLECULAR structure
Zdroj:	Journal of Structural Chemistry; Mar2006, Vol. 47 Issue 2, p220-231, 12p, 1 Diagram, 5 Charts, 1 Graph
Abstrakt:	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. [ABSTRACT FROM AUTHOR]
Databáze:	Complementary Index
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