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Carbon‐13 and related NMR chemical shifts in alkylammonium and alkylphosphonium salts
Author(s) -
Evans David J.,
Leigh G. Jeffery,
Macdonald Colin J.
Publication year - 1990
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.1260280810
Subject(s) - chemistry , chemical shift , carbon fibers , alkyl , carbon 13 nmr , crystallography , medicinal chemistry , inorganic chemistry , stereochemistry , organic chemistry , materials science , composite number , composite material
The 13 C NMR chemical shifts of the α‐carbon atoms in cations [NR 4 ] + , [NR 3 CH 2 Ph] + and [PR 4 ] + [R = Me, Et, Pr n , Bu n or Pe n ( n ‐pentyl)] are found at anomalously high field in comparison with the corresponding shifts in RCl or RNH 2 . This is ascribed in part to the effect of the positive charge. The effect is detectable but less pronounced with β‐carbon atoms, but is not detectable in subsequent carbon atoms in longer alkyl chains.