N-oxide Derivatives - Car-Parrinello Molecular Dynamics and ELF Study on Intramolecular Hydrogen Bonds

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2018-07
• Main Authors: Panek, Jaroslaw Jan, Jezierska, Aneta Bozena
• Format: Article
• Language: English
• ISSN: 1520-5215

First-principle molecular dynamics simulations (CPMD) and Electron Localization Function (ELF) topological analysis were performed for two N-oxides, 2-(N,N-dimethylamino-N-oxymethyl)-4,6-dimethylphenol (I) and 5,5'-dibromo-3-diethylaminomethyl-2,2'-biphenol N- oxide (II). Special attention was paid to hydrogen bonds dynamics and spectroscopic features. Simulations were carried out in vacuo and in the crystalline phase. It was found that for the compound I proton transfer phenomena do not occur spontaneously. An opposite situation was noticed for one of the two intramolecular hydrogen bonds of the compound II. The influence of the neighboring molecules (including microsolvation) and the crystal field on the hydrogen bond properties cannot be neglected. Hydrogen bonds spectroscopic signatures were quite well reproduced by power spectra of atomic velocity. Metric and spectroscopic theoretical findings were compared with experimental data available, especially in a view of the fact that experimental X-ray diffraction and FT-IR data of the compound II indicate strong delocalization of the N-oxide bridge proton. ELF analysis showed that for the compound II the N-oxide bridge belongs to the topological category of strong hydrogen bonds with the separate ELF basin for the bridged hydrogen atom.