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A proton spin–lattice relaxation rate and nuclear Overhauser effect investigation of the stereochemistry of some 1‐aryl derivatives of 1,2‐dihydro‐ s ‐triazines
Author(s) -
Peiris Sriyawathie,
Colebrook Lawrence D.
Publication year - 1984
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270220407
Subject(s) - conformational isomerism , diastereomer , chemistry , nuclear overhauser effect , enantiomer , aryl , relaxation (psychology) , proton , proton nmr , spin–lattice relaxation , proton spin crisis , stereochemistry , nuclear magnetic resonance , computational chemistry , nuclear magnetic resonance spectroscopy , molecule , organic chemistry , physics , psychology , social psychology , alkyl , quantum mechanics
Proton spin–lattice relaxation rates ( R 1 values) have been measured, at 400 MHz, for a number of 2‐methyl‐ and 2,2‐dimethyl‐substituted 4,6‐diamino‐1‐aryl‐1,2‐dihydro‐ S ‐triazines. These compounds have high barriers to internal rotation about the aryl CN bond, and exist in solution as mixtures of enantiomeric or diastereomeric rotational isomers. Diastereotopically related 2‐methyl groups in enantiomeric rotamers, and 2‐methyl and 2‐methine protons in diastereomeric rotamers, typically have different relaxation rates. In favourable circumstances this information may be used to identify the individual rotamers. Unequivocal direct identification of rotamers may be obtained from nuclear Overhauser effect difference spectra.