Conformational study, molecular structure, and S…H‒N, S‒H…N intramolecular hydrogen bond in thioformyl-3-aminoacrylaldehyde

Abstract

The molecular structure and intramolecular hydrogen bond (HB) energies of 42 conformers of thioformyl3-aminoacrylaldehyde (TFA) were investigated at HF, Moller–Plesset theory and B3LYP levels of theory using the 6-311++G∗∗ basis set. HB energies for all conformers were obtained from the Espinosa method. In this method, the H-bond energies may be estimated from the properties of bond critical points. In addition, harmonic vibrational frequencies were evaluated at the same levels to confirm the nature of the stationary points found and also to account for the zero point vibrational energy correction. Furthermore, the atoms in molecules theory of Bader that is based on topological properties of the electron density (ρ) was used to analyze critical points and to study the nature of the HB in these systems. Natural bond orbital analysis was also performed for better understanding the nature of intramolecular interactions in TFA