Parameters, Calculation of Nuclear Magnetic Resonance

Abstract

The fundamental parameters that reproduce a nuclear magnetic resonance ( NMR ) spectrum in gases, liquids, and solids are the NMR chemical shift of the nucleus, the indirect nuclear spin–spin coupling, and the nuclear quadrupole coupling. All three quantities are tensors whose directional properties are intimately related to the local electronic structure at the nucleus; the third is trivially related to the electric field gradient (EFG) at the nucleus, so we consider the latter. The theoretical methods used in calculating the shielding (which is measured as a chemical shift relative to some convenient reference substance), the J ‐coupling, and the EFG are considered here, also the challenges in the accurate calculation of these quantities, including relativistic effects, dynamics, and solid‐state effects. The sensitivity to intramolecular geometry, local and long‐range environment, and dynamic averaging that make these NMR parameters particularly useful as probes for analysis also provide major challenges in carrying out theoretical calculations.

Four-component relativistic 31P NMR calculations for trans-platinum(ii) complexes: importance of the solvent and dynamics in spectral simulations

“…So far, the accurate prediction of heavy-metal nucleus NMR parameters poses challenges for quantum chemistry. [22][23][24] Calculated relativistic effects in the vicinity of a heavy metal are generally very sensitive to the character of metal-ligand bonding and the inclusion of environmental effects. Hence, specific difficulties arise when solvation is expected to be important, for which it is necessary to go beyond a static description and one needs to include the solvent dynamics.…”