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Residual ( 13 C, 14 N) dipolar coupling in 13 C NMR of solid nitrogen‐containing aromatic compounds
Author(s) -
Harris R. K.,
Jonsen P.,
Packer K. J.
Publication year - 1985
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.1260230716
Subject(s) - chemistry , diazo , quadrupole , dipole , nmr spectra database , nitrogen , coupling constant , electric field gradient , spectral line , crystallography , atomic physics , organic chemistry , physics , particle physics , astronomy
Carbon‐13 NMR spectra of some solid substituted anilines and aromatic diazonium salts, taken under conditions of cross‐polarization with high‐power proton decoupling, are presented. In the case of the aromatic diazo compounds the carbon directly attached to the diazo group gives rise at 22.6 MHz to a line shape which has approximately the appearance of a 2:1:1 triplet but which is shown to be in reality a 2:1 doublet of 2:1 doublets. This arises from the presence of both a long‐range and a short‐range residual ( 13 C, 14 N) dipolar coupling. Isotopic labelling of the nitrogen in the diazo group allowed the determination of the nuclear quadrupole coupling constants of the two 14 N nuclei and, consequently, theoretical simulation of the apparent triplet line shape. The orientations of the electric field gradient tensors for the 14 N nuclei in these compounds are discussed in terms of their electronic structure.