The Symmetrization Postulate of Quantum Mechanics in NMR Spectra

Abstract

Abstract In NMR spectroscopy, consequences of the symmetrization postulate of quantum mechanics for groupings of identical atomic nuclei are usually ignored. A common view is that only in rare instances this general practice must be suspended. However, according to recent experimental and theoretical findings, such instances are not so exotic as it is generally believed. Occurrence of the so-called quantum exchange couplings, stemming from the spin-space correlations imposed by the symmetrization postulate, is now routinely oberved in liquid-phase NMR of some transition metal tri-and dihydrides. Moreover, most recent studies on the dynamics of methyl-type molecular rotors reveal that even stochastic motions of such nuclear systems, generally treated as classical par excellence, can in fact be shaped up by the symmetrization postulate. Interestingly, the quantum nature of such motions can be visible not only at cryogenic but also at ambient temperatures. The main issues that are addressed in the present review include manifestations of the symmetrization postulate in NMR spectra of the metal hydrides and methyl-type rotors. Emphasis is laid on the new developments in the field as well as on the relevant problems that await further analysis.