Solvent Effects on the NMR Parameters

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. Q 1999 John Wiley & Sons, Inc. J Comput Chem 20: 1281]1291, 1999