Theoretical gas to liquid shift of 15 N isotropic nuclear magnetic shielding in nitromethane using ab initio molecular dynamics and GIAO/GIPAW calculations

I.C. Gerber (1) , Franck Jolibois (1)

1 LPCNO - Laboratoire de physique et chimie des nano-objets

Chemical shift requires the knowledge of both the sample and a reference magnetic shielding. In few cases as nitrogen (15N), the standard experimental reference corresponds to its liquid phase. Theoretical estimate of NMR magnetic shielding parameters of compounds in their liquid phase is then mandatory but usually replaced by an easily-get gas phase value, forbidding direct comparisons with experiments. We propose here to combine ab initio molecular dynamic simulations with the calculations of magnetic shielding using GIAO approach on extracted cluster's structures from MD. Using several computational strategies, we manage to accurately calculate 15N magnetic shielding of nitromethane in its liquid phase. Theoretical comparison between liquid and gas phase allows us to extrapolate an experimental value for the 15N magnetic shielding of nitromethane in gas phase between -121.8 and -120.8 ppm.

Domaines: Chimie théorique et/ou physique

I.C. Gerber, Franck Jolibois. Theoretical gas to liquid shift of 15 N isotropic nuclear magnetic shielding in nitromethane using ab initio molecular dynamics and GIAO/GIPAW calculations. Physical Chemistry Chemical Physics, 2015, 17 (18), pp.12222-12227. ⟨10.1039/c5cp00722d⟩. ⟨hal-02366310v2⟩