Nuclear magnetoelectric shieldings for chiral discrimination in NMR spectroscopy. Theoretical study of (Ra)-1,3-dimethylallene, (2R)-2-methyloxirane, and (2R)-N-methyloxaziridine molecules

Dynamic magnetoelectric shieldings at the nuclei, having the same magnitude butopposite sign in D and L enantiomers, have been evaluated at the random-phase approximationlevel of accuracy for three chiral molecules of medium size. For frequencies normally operatedin nuclear magnetic resonance spectroscopy, calculated values are probably too small to bedetectable in disordered phase. Within the same experimental conditions, the isotropic part ofnuclear magnetic shielding polarizability and a related pseudoscalar provide contributions 3 ordersof magnitude bigger than the average magnetoelectric shieldings to (i) the magnetic field inducedat a resonant nucleus and (ii) the induced electric dipole of electrons rotating at the Larmorfrequency; therefore, nuclear magnetic shielding polarizabilities are probably more suitable thannuclear magnetoelectric shieldings for chiral discrimination in nuclear magnetic resonancespectroscopy.