Premium
Tris(dipivaloylmethanato)europium induced shifts of proton resonances in π‐deficient nitrogen heterocycles
Author(s) -
Armarego W. L. F.,
Batterham T. J.,
Kershaw J. R.
Publication year - 1971
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.1270030512
Subject(s) - cinnoline , chemistry , pyridazine , pyrazine , phthalazine , acridine , quinazoline , europium , quinoline , quinoxaline , phenanthridine , medicinal chemistry , isoquinoline , benzothiophene , steric effects , pyridine , diazine , protonation , photochemistry , stereochemistry , thiophene , organic chemistry , ion
Abstract Tris(dipivaloylmethanato)europium [Eu(DPM) 3 ]induced shifts of the proton resonances of pyridine and its 2‐methyl, 3‐methyl, 2,3‐dimethyl and 2,5‐dimethyl derivatives, pyridazine, pyrimidine, pyrazine, quinoline, isoquinoline, 1,6‐, 1,7‐ and 1,8‐naphthyridine, cinnoline, phthalazine, quinazoline, quinoxaline, 1,4,5‐ and 1,4,6‐triazanaphthalene, pteridine, acridine, phenanthridine and 1, 10‐phenanthroline, have been measured for solutions containing 0·1, 0·3 and 0·5 molar equivalents of Eu(DPM) 3 . Differences in the behaviour of these heterocycles are discussed in terms of the steric relationship between the heterocycle and the complex. The 3 cos 2 ϕ term, present in the expression for calculating pseudo‐contact shifts, is shown to be important. The order of basicity of these heterocycles, as measured by their pK a values, cannot be used to predict the order of Eu(DPM) 3 induced chemical shifts.