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    (Br) Bromine NMR 79Bromine NMR Properties of 79Br 81Bromine NMR Properties of 81Br Safety note References
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  • Properties of 79Br
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  • Properties of 81Br
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(Br) Bromine NMR

Use our NMR service that provides Br NMR and many other NMR techniques.

Bromine (Br) has two NMR active nuclei, 79Br and 81Br with a wide chemical shift range (fig. 1). Both nuclei are quadrupolar and therefore yield broad signals as ions in symmetrical environments and signals, too broad to be observed with a high-resolution NMR spectrometer, even in small molecules. As a result bromine NMR is restricted to relaxation studies of the binding of bromide ions. 81Br is the more sensitive nucleus and yields slightly narrower signals than 79Br (fig. 2) so 81Br is the nucleus of choice. However, 79Br has a frequency very similar to 13C (fig. 3) and is often observable using a carbon specific probe. Because of this and because it produces clear quadrupolar spinning sidebands in the solid state (fig. 4), it is widely used in solid state NMR for adjusting the magic angle. There is very little information about bromine chemical shifts (fig. 1).

Fig. 1. Chemical shift ranges for bromine NMR

Chemical shifts of bromine

Fig. 2. Comparison of 79Br and 81Br for KBr in D2O. 81Br is the more sensitive nucleus and yields narrower signals.

Comparison of 79Br and 81Br spectra

Fig. 3. The signal of 79Br (right) in the same spectrum as the 13C signals (left) for KBr and acetone in D2O. The chemical shift scales are for 13C (top) and 79Br (bottom).

13C and 79Br signal in the same spectrum

79Bromine NMR

79Br (fig. 5) is less sensitive and yields broader signals than 81Br so it is not usually the nucleus of choice for liquid NMR. However, 79Br has a frequency very similar to 13C (fig. 3) and is often observable using a carbon specific probe. Because of this and because it produces clear quadrupolar spinning sidebands in the solid state (fig. 4), it is widely used in solid state NMR for adjusting the magic angle.

Fig. 4. 79Br-NMR spectrum of solid KBr showing spinning sidebands used for adjusting the magic angle

79Br solid-state spectrum

Fig. 5. 79Br-NMR spectrum of KBr in D2O

79Br spectrum

Properties of 79Br

(Click here for explanation)

PropertyValue
Spin3/2
Natural abundance50.69%
Chemical shift range600 ppm, from -500 to 100
Frequency ratio (Ξ)25.053980%
Reference compoundNaBr (0.01 M) in D2O
Linewidth of reference648 Hz
T1 of reference0.0005 s
Receptivity rel. to 1H at natural abundance0.0403
Receptivity rel. to 1H when enriched0.0795
Receptivity rel. to 13C at natural abundance237
Receptivity rel. to 13C when enriched468
Linewidth parameter1300 fm4

81Bromine NMR

81Br (fig. 6) is the bromine nucleus of choice, at least for liquid-state NMR, as it is more sensitive and yields narrower signals than 79Br.

Fig. 6. 81Br-NMR spectrum of KBr in D2O

81Br spectrum

Properties of 81Br

(Click here for explanation)

PropertyValue
Spin3/2
Natural abundance49.31%
Chemical shift range600 ppm, from -500 to 100
Frequency ratio (Ξ)27.006518%
Reference compoundNaBr (0.01 M) in D2O
Linewidth of reference467 Hz
T1 of reference0.002 s
Receptivity rel. to 1H at natural abundance0.0491
Receptivity rel. to 1H when enriched0.0996
Receptivity rel. to 13C at natural abundance288
Receptivity rel. to 13C when enriched584
Linewidth parameter920 fm4

Safety note

Some of the materials mentioned here are very dangerous. Ask a qualified chemist for advice before handling them. Qualified chemists should check the relevant safety literature before handling or giving advice about unfamiliar substances. NMR solvents are toxic and most are flammable. Specifically, bromide is toxic in large doses. Other oxidation states of bromine are toxic: wear gloves.

References

  • G. Lindblom, B. Lindman and L. Mandell "Study of counter-ion binding to reversed micelles by nuclear magnetic quadrupole relaxation of bromine-81" J. Coll. Interface Sci., 34, 262-71, (1970).
  • P. Diehl, E. Fluck and R. Kosfeld, Eds., "NMR, Basic Principles and Progress, Vol. 12: Chlorine, Bromine and Iodine NMR. Physico-Chemical and Biological Applications." Springer, Berlin, Ger. (1976).
  • T. Drakenberg and S. Forsen, "[NMR of] the halogens - chlorine, bromine, and iodine" NATO ASI Series, Series C: Mathematical and Physical Sciences 103 (Multinucl. Approach NMR Spectrosc.), 405-44 (1983).