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Lanthanide‐induced shifts in proton NMR spectra—IV: Praseodymium‐induced shifts to lower applied fields and obscured chemical shifts from lanthanide‐induced shift (LIS) data
Author(s) -
Hlubucek J. R.,
Shapiro B. L.
Publication year - 1972
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.1270040606
Subject(s) - lanthanide , chemistry , praseodymium , chemical shift , proton , molecule , proton nmr , reagent , molar ratio , naphthalene , spectral line , inorganic chemistry , stereochemistry , catalysis , organic chemistry , ion , physics , quantum mechanics , astronomy
Praseodymium(III) tris(dipivalomethanato) [Pr(DPM) 3 ] reduces the complex overlapping aromatic absorptions in the proton NMR spectrum of a monosubstituted naphthalene, cis ‐3‐(1‐naphthyl)‐1,3,5,5‐tetramethlcyclohexan‐1‐ol( 1 ) to a virtually first‐order pattern, whereas Eu(DPM) 3 at the same and higher molar concentrations does not completely resolve the aromatic proton signals. Plots of the Pr(DPM) 3 ‐induced shifts measured in carbon tetrachloride solution versus molar equivalents of Pr(DPM) 3 added may be extrapolated to provide accurate chemical shifts in the absence of added lanthanide shift reagent (LSR). The qualitative conformational conclusions from the Pr(DPM) 3 shifts agree with those from the Eu(DPM) 3 ‐induced shifts, but there are detailed differences in the relative lanthanide‐induced shifts (LIS) for different proton types in the molecule.