Solvent effects on the NMR parameters of H2S and HCN

Abstract

A recently developed method to calculate singlet and triplet gauge-origin–independent magnetic properties of solvated molecules is applied to the study of those parameters that determine an observed nuclear magnetic resonance signal: the magnetizability, the nuclear shieldings, and the indirect spin–spin coupling constants. The solvent is represented by a dielectric medium and the electronic structure of the solvated molecule by Hartree–Fock and multiconfigurational Hartree–Fock wave functions. For the properties that depend on the external magnetic field, we use London atomic orbitals to ensure gauge-origin independence and a rapid basis-set convergence. We find that the dielectric-medium effects on these molecules are substantial, being of the same order as rovibrational and electron correlation effects, and thus cannot be neglected if accurate comparisons with liquid-phase measurements are wanted. However, the present model is incapable of describing the close-range interactions that may occur in solution. It, therefore, represents the electrostatic effects of the bulk solvent, and the model is an initial approach towards a complete ab initio model for the study of magnetic properties of solvated molecules. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 1281–1291, 1999