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Analysis of 1 H NMR spectra of fluorene and azafluorenes: Long‐range coupling constants
Author(s) -
Fomichov A. A.,
LawaniEdogiawerie S. O.,
Prostakov N. S.
Publication year - 1983
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/omr.1270210505
Subject(s) - fluorene , coupling constant , chemistry , pyridine , resonance (particle physics) , ring (chemistry) , chemical shift , spectral line , heteroatom , nmr spectra database , crystallography , nitro , medicinal chemistry , atomic physics , organic chemistry , physics , alkyl , particle physics , astronomy , polymer
Analyses of the 1 H NMR spectra of fluorene, 2‐nitrofluorene, 1‐azafluorene, 2‐azafluorene, 4‐azafluorene, 7‐nitro‐4‐azafluorene and 1,4‐diazafuorene have been carried out using computer calculations and homo double resonance techniques. The relative signs and magnitude of the 4 J , 5 J and 6 J long‐range coupling constants of the 9‐CH 2 group protons with the pyridine and phenylene ring protons have been measured by five‐ and six‐spin calculations. It was established that the presence of substituents and the N heteroatom has only a very weak effect on the values and signs of these coupling constants. The usual alternating signs of long‐range coupling constants involving π‐electron systems were confirmed, giving negative signs for even and positive signs for odd numbers of bonds separating the coupling protons.