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Accurate determination and analysis of the temperature dependence of long‐range spin–spin couplings in 2‐chlorobenzaldehyde
Author(s) -
Laatikainen Reino,
Tuppurainen Kari,
Hiltunen Yrjö,
Lötjönen Simo
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.1260281107
Subject(s) - chemistry , dihedral angle , planarity testing , spin (aerodynamics) , ring (chemistry) , proton , planar , sign (mathematics) , proton spin crisis , atmospheric temperature range , range (aeronautics) , coupling (piping) , computational chemistry , molecular physics , crystallography , molecule , thermodynamics , organic chemistry , hydrogen bond , nuclear physics , materials science , composite material , mathematical analysis , physics , computer graphics (images) , mathematics , computer science , mechanical engineering , engineering
The proton‐proton spin‐spin couplings of 2‐chlorobenzaldehyde were determined accurately for acetone‐ d 6 and CD 3 CN solutions at several temperatures. The sign and temperature dependence of the para ‐benzylic six‐bond coupling, 6 J α4 , was also obtained, although the observed value of this indicator of the formyl–ring co‐planarity was in the range −24 to −31 mHz. The fitting of the temperature dependence suggests that 6 J 0 (the value of the coupling when the formyl‐ring dihedral angle is 0°) is very small and probably positive, in contrast, for example, to styrene. The results are discussed on the basis of some modified INDO/FP calculations. A simple resolution enhancement technique is also described.