Nuclear magnetic shielding of molecule in solution based on reference interaction site model self-consistent field with spatial electron density distribution

Abstract

A new method for calculating nuclear magnetic shielding in solutions is developed based on the reference interaction site model self-consistent field (RISM-SCF) with spatial electron density distribution (SEDD). In RISM-SCF-SEDD, the electrostatic interaction between the solute and the solvent is described by considering the spread of electron to obtain more realistic electronic structure in solutions. It is thus expected to allow us to predict more quantitative chemical shifts of a wide variety of chemical species in solutions. In this study, the method is applied to a water molecule in water and is validated by examining the dependence of the solvent temperature and density on chemical shifts. The dependence of solvent species is also investigated, and more accurate results are obtained for polar solvents compared to the previous RISM-SCF study. Another application example of this method is the 15 N chemical shifts of two azines in water, which is difficult to predict with the polarizable continuum model (PCM). Our results are in good agreement with the previous quantum mechanical/molecular mechanics study and experimental results. It is also shown that our method gives more realistic results for methanol and acetone than the PCM.

Chemical Shift of Solvated Hydride Ion: Comparative Study with Solvated Fluoride Ion

“…At present, it is not easy to study the chemical shifts of hydrides experimentally, but ab initio calculations offer an alternative. Previous studies showed that the calculated chemical shifts are in quantitative agreement with experimental results . Even in the case of very low abundances of ions and weak peak intensities, computational studies can provide information on the physicochemical background as well as on the possibility of detection.…”

“…In order to consider the solvent effect outside the cluster structure, we employ the latest technique that combines the framework of RISM-SCF-SEDD and the use of GIAOs . RISM-SCF-SEDD is a hybrid method that combines quantum chemical calculations with statistical mechanics of molecular liquids.…”

“…In MP2 calculations, the frozen core approximation is not applied. In order to consider solvent effects outside the first solvation shell in a statistically converged manner, chemical shifts are also calculated by RISM-SCF-SEDD method combined with Gaussian 16 …”

“…Previous studies showed that the calculated chemical shifts are in quantitative agreement with experimental results. 14 Even in the case of very low abundances of ions and weak peak intensities, computational studies can provide information on the physicochemical background as well as on the possibility of detection. There have been several theoretical studies concerning the solvation of hydride ion, but all of them deal with the hydrated cluster consisting of a hydride ion and water molecules.…”

Evaluation of an Efficient 3D-RISM-SCF Implementation as a Tool for Computational Spectroscopy in Solution

“…We have seen above in the context of solvatochromism that water is a rather special solvent within a RISM framework, not necessarily the best-suited case (see also below). Very recently, Sato and co-workers presented an implementation using RISM-SCF-SEDD for the calculation of NMR shifts . The authors investigated the 15 N chemical shifts of pyrazine in different solvents and found a trend comparable to the experimentally observed one.…”