Calculation of the Tautomeric Properties of 3-Formyl-Tetrinic Acid by the ab initio and DFT Methods
Source: Journal of Applied Spectroscopy, Volume 68, Number 3, 6 May 2001 , pp. 401-409(9)
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 MøllerPlesset second-order perturbation theory with the use of a 631G(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 PerdewBurkeErnzerhof (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.
Document Type: Regular paper
Affiliations: 1: Photochemistry Center, Russian Academy of Sciences, 7a Novatorov Str., Moscow, 117421, Russia email@example.com 2: Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus
Publication date: 2001-05-06