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Conformational analysis 18 —lanthanide‐induced shift (LIS) investigation of some 2‐substituted 1,3‐dioxanes
Author(s) -
Abraham Raymond J.,
Wallace Kerry,
Wilkins Suzanne,
Sancassan Fernando
Publication year - 1992
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/mrc.1260301018
Subject(s) - chemistry , lanthanide , lanthanum , denticity , isopropyl , oxygen atom , crystallography , lone pair , stereochemistry , molecule , crystal structure , medicinal chemistry , inorganic chemistry , organic chemistry , ion
Abstract A LIS analysis of 2‐isopropyl‐1,3‐dioxane (1) and 2‐methyl‐2‐phenyl‐1,3‐dioxane (2) is reported. The monodentate complexing model gives good agreement with the observed shifts in both compounds, whereas the bidentate model (lanthanum binding to both oxygens) does not give an acceptable solution. In 1 the lanthanide complexes almost exclusively (90%) with the axial lone pair of the oxygen atom. The four‐site binding model gives excellent agreement with the observed shifts ( R x 3.5%). In 2 a similar lanthanide binding is found, and the analysis of the LIS allows both the deduction of the molecular conformation (C‐2‐methyl equatorial, C‐2‐phenyl axial) and also the orientation of the phenyl group (perpendicular).