Shielding and spin-spin coupling constants from gas-phase NMR

Abstract

Abstraet. Intermolecular interactions modify nuclear magnetic resonance (NMR) chemical shifts and spin-spin coupling constants. The intermolecular effects can be determined if the NMR parameters for an isolated molecule are known+ Gas-phase NMR spectroscopy offers such methods which allow one to measure the shielding and spin-spin coupling constants at the zero-density lirnit where the NMR parameters are free from intermolecular contributions. It is also shown that at present the multinuclear NMR spectra can easily be obtained for gaseous samples containing several micrograms of a solute compound.

A relativistic DFT study of one-bond fluorine-X indirect spin–spin coupling tensors

“…Indirect spin-spin coupling and magnetic shielding constants are known to be sensitive to molecular geometry and also intermolecular effects. 30,70 We have attempted to find reliable structures for this investigation, and have used both gas-and solidphase structures obtained by various experimental methods, including gas-phase electron diffraction, solid-state x-ray and neutron diffraction and liquid-crystal NMR studies. Intermolecular effects and vibrational effects 71 on J have not been considered; calculated and experimental data will be compared without a detailed discussion considering the impact of a solvent or of a change of state on the observed results.…”