Premium
Primary tritium and deuterium isotope effects on chemical shifts of compounds having an intramolecular hydrogen bond †
Author(s) -
Bolvig Simon,
Hansen Poul Erik,
Morimoto Hiromi,
Wemmer David,
Williams Philip
Publication year - 2000
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/1097-458x(200007)38:7<525::aid-mrc663>3.0.co;2-s
Subject(s) - kinetic isotope effect , chemistry , deuterium , tritium , intramolecular force , tautomer , hydrogen , deuterium nmr , hydrogen bond , isotope , primary (astronomy) , radiochemistry , organic chemistry , nuclear magnetic resonance spectroscopy , molecule , nuclear physics , physics , astronomy
The primary deuterium and tritium isotope effects, δ(XH) − δ(XD/T), were measured for 55 compounds having one or more intramolecular hydrogen bonds. The primary isotope effects were measured at various temperatures. For compounds displaying tautomerism the primary isotope effects are found to have contributions from both intrinsic and equilibrium isotope effects. The primary tritium isotope effect, P Δ( 1 H, 3 H), and the primary deuterium isotope effect, P Δ ( 1 H, 2 H), are shown to be related by$$ ^{\rm P}\Delta (^{1}\hbox{H},^{3}\hbox{H}) =1.4 ^{\rm P}\Delta (^{1}\hbox{H},^{2}\hbox{H}) $$This finding is valid for both tautomeric compounds and compounds with localized hydrogen bonds. Large negative primary tritium and deuterium isotope effects were observed for compounds displaying tautomerism and having sulfur as donor or acceptor. These isotope effects show a strong temperature dependence, which is related to the change in equilibrium due to isotope substitution. For the compounds with localized hydrogen bonds, the primary deuterium and tritium isotope effects correlated with the two bond deuterium isotope effect on 13 C chemical shifts. The primary deuterium and tritium isotope effects are therefore a measure of the hydrogen bond strength for compounds with localized hydrogen bonds. Copyright © 2000 John Wiley & Sons, Ltd.