Nuclear magnetic dipole moments from NMR spectra-quantum chemistry and experiment

Abstract

We discuss new values of nuclear magnetic dipole moments, obtained from accurate absolute shielding constants and gas-phase NMR data, for a series of nuclei. The generally accepted previous values of magnetic moments were for many isotopes derived from NMR spectra. However, in the procedure applied to determine the moments of bare nuclei the effects of the molecular electronic structure have been often described in a very approximate manner. Accurate absolute shielding scales can be presently established analysing gas-phase NMR spectra and shielding constants determined by ab initio methods of quantum chemistry. We present a systematic analysis of the nuclear magnetic moments, based on the relation between these moments, the resonance frequencies and the shielding constants. With the new values of nuclear magnetic dipole moments the relations between the NMR parameters of different nuclei are fulfilled in a consistent manner, whereas using the literature values leads to significant errors. © 2008 Springer-Verlag Berlin Heidelberg.