Investigations of the hydrogen bond in the crystals of tropolone and thiotropolone via car-parrinello and path integral molecular dynamics.
J Comput Chem
; 40(4): 671-687, 2019 Feb 05.
Article
em En
| MEDLINE
| ID: mdl-30549082
ABSTRACT
Car-Parrinello and path integrals molecular dynamics (CPMD and PIMD) simulations were carried out for the 10π-electron aromatic systems 2-hydroxy-2,4,6-cycloheptatrien-1-one, commonly known as Tropolone (I) and 2-hydroxy-2,4,6-cycloheptatriene-1-thione, called Thiotropolone (II) in vacuo and in the solid state. The extremely fast proton transfer (FPT) and "prototropy" tautomerism in the keto-enol (thione-enethiol) systems have been analyzed on the basis of CPMD and PIMD methods level. Comparisons of two-dimensional (2D) free-energy landscapes of reaction coordinate δ-parameter and RO
O or RO
S distances shows that the OH
tautomer to be more favorable in the Thiotropolone. The hydrogen between the oxygen and the sulfur atoms adopts a starkly asymmetrical position in the double potential well. The values of the energy barriers for the FPT were calculated and suggested a strong hydrogen bond with low barrier for FPT mechanism. These studies and the 2D average index of π-delocalization ãλã landscape of time evolutions of RO1
O2 and RC7O2 or RC7S1 distances for the both crystals indicate that hydrogen bonds in the crystals of Tropolone (I) and Thiotropolone (II) have characteristic properties for the type of bonding model resonance-assisted hydrogen bonds and also low-barrier hydrogen bonds. In the crystal of the Thiotropolone (II), we found the hydrogen bond OH
S existing without the equilibrium of the two tautomers whereas in the crystal of the Tropolone (I) has been confirmed the hydrogen bond OH
O existing with the equilibrium of the two tautomers. It was also found the significant differences in frequency, speed, and the image of the FPT in the studied crystals. © 2018 Wiley Periodicals, Inc.
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Base de dados:
MEDLINE
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
J Comput Chem
Assunto da revista:
QUIMICA
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Polônia