The Effect of Fluorine Substituents on 15N Chemical Shifts

FIGURE 2.2. H6-N cross peak in a 1H-15N gHSQC experiment with 2-fluoropyridine 

With many compounds of interest to both pharmaceutical and agrochemical chemists containing nitrogen, and with the increasing capabilities of modern NMR instrumentation, the potential for use of 15N NMR data in structure characterization is beginning to be recognized and utilized. Substituent effects on 15N chemical shifts can be quite dramatic, and the relatively few data that are available 

To give the reader some perspective of the large range of 15N chemical shifts, secondary aliphatic amines such as pyrrolidine have chemical shifts in the range of 38 ppm, aniline (54), primary amides ( 105), benzonitrile (256), pyridine (317), pyrrole (146), pyrazole N-1 (207), N-2 (399), imidazole (211), pyridazine (400), pyrimidine (295), and pyrazine (333).9 

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