Electric field effects on nuclear spin–spin coupling tensors and chiral discrimination via NMR spectroscopy

G. I. PAGOLA; M. B. FERRARO; S. PELLONI; P. LAZZERETTI; S.P.A. SAUER

THEORETICAL CHEMISTRY ACCOUNTS

SPRINGER

Lugar: New York; Año: 2010 vol. 127 p. 429 - 763

1432-881X

Nuclear magnetic resonance spectrometers 9 presently available are unable to recognize the two mirror- 10 image forms of a chiral molecule, because in the absence of 11 a chiral solvent, the NMR spectral parameters (chemical 12 shifts and spin–spin coupling constants) are identical for 13 the two enantiomers. This paper discusses how chirality 14 may nevertheless, at least in theory, be recognized in 15 liquid-state NMR spectroscopy by applying strong d.c. 16 electric fields and measuring a pseudoscalar contribution to 17 nuclear spin–spin coupling polarizability. Calculations are 18 reported for medium-size chiral molecules, (2R)-N-meth- 19 yloxaziridine, (Ra)-1,3-dimethylallene, and (2R)-2-methy- 20 loxirane. The very small contributions provided by the 21 pseudoscalar of nuclear spin–spin coupling polarizability seem rather difficult to detect via NMR experiments in 22 disordered phase.