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Nitroxide radical as a probe for molecular conformation. Part I. 13 C NMR study of the interaction of N,N ‐dimethylamides with nitroxide radical
Author(s) -
Wawer Iwona,
Ströhl Dieter,
Kleinpeter Erich
Publication year - 1993
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.1260310813
Subject(s) - chemistry , nitroxide mediated radical polymerization , mndo , molecule , amide , radical , planarity testing , stereochemistry , acceptor , stereospecificity , computational chemistry , crystallography , radical polymerization , organic chemistry , polymerization , catalysis , polymer , physics , condensed matter physics
13 C NMR contact shifts induced by the 2,2,6,6,‐tetramethylpiperidine nitroxide radical (TMPN) were measured for N , N ‐dimethyl‐ para ‐substituted benzamides and N , N ‐dimethyl‐β‐bromo‐ and ‐α,β‐methylacrylamides. The shifts were linear functions of radical concentration, c r . It was found that N ‐methyl group anti to the carbonyl group is a better acceptor site than the syn ‐ N ‐methyl group and that there is a relationship between Δδ/dc r and the non‐planarity of molecules of amides with an s ‐skew conformation. The electrostatic potential of amide molecules obtained from MNDO calculations was used to predict the stereospecific interaction with radicals.