Calculation of the Tautomeric Properties of 3-Formyl-Tetrinic Acid by the ab initio and DFT Methods

Authors: Avakyan V.G.¹; Gromak V.V.²

Source: Journal of Applied Spectroscopy, Volume 68, Number 3, 6 May 2001 , pp. 401-409(9)

Publisher: Springer

Buy & download fulltext article:

Price: $47.00 plus tax (Refund Policy)

Abstract:

We have carried out a nonempirical quantum-chemical calculation with full optimization of the geometry of all theoretically possible tautomeric forms of 3-formyl-tetrinic acid (FTRA) according to the Møller–Plesset second-order perturbation theory with the use of a 6–31G(d) double zeta basis set. The correlation corrections to the total energy of molecules for optimized geometric configurations were calculated in the 6-31G(d,p) basis. All the possible tautomeric forms of FTRA and the harmonic vibrational frequencies were also calculated within the density functional theory (DFT) with the use of the Perdew–Burke–Ernzerhof (PBE) functional in a three-exponent basis. It is shown that FTRA in vapors (in the perfect gas approximation) exists in the form of a mixture of three enol forms, among which two exo-forms predominate. The frequencies and forms of normal vibrations for each cis-enol tautomer in the region of vibrations of keto-groups and double bonds differ widely, which permits identification of the tautomers present in the mixture. The possible mechanisms of enol-enol transformations of 3-acyltetrinic acids are discussed.

Keywords: ab initio calculation; calculation by the DFT method; 3-formyl-tetrinic acid; tautomerism of bgr , bgr '-triketones; intramolecular hydrogen bond

Language: English

Document Type: Regular paper

Affiliations: 1: Photochemistry Center, Russian Academy of Sciences, 7a Novatorov Str., Moscow, 117421, Russia avak@photonics.ru 2: Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus

Publication date: 2001-05-06