(I) Iodine NMR

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ü    References

ü    127I

ü    Properties of 127I

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, iodide is toxic in large doses. Other oxidation states are more toxic: wear protective gloves.

 

127Iodine NMR

Iodine (Br) has one NMR active nucleus, 127I with a very wide chemical shift range. The nucleus is of medium to high sensitivity but is quadrupolar and yields very broad signals as ions in symmetrical environments and signals, too broad to be observed with a high-resolution NMR spectrometer, even in ionic clusters and small molecules. The relaxation time of the I4- ion has been measured to be 110 ns, corresponding to a line-width of 6 MHz, much too wide to be observed with a high-resolution NMR spectrometer. As a result, 127I NMR is restricted to relaxation studies of the binding of iodide ions.

There is very little information about iodine chemical shifts.

Chemical shift ranges for iodine NMR

 

127I-NMR spectrum of KI (1M) in D2O

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Properties of 127I

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Spin

5/2

Natural abundance

100%

Chemical shift range

4200 ppm, from -100 to 4100

Frequency ratio (Ξ)

20.007486%

Reference compound

KI (0.01 M) in D2O

Linewidth of reference

1926 Hz

T­1 of reference

0.000135 s

Receptivity rel. to 1H at natural abundance

0.0954

Receptivity rel. to 1H when enriched

0.0954

Receptivity rel. to 13C at natural abundance

560

Receptivity rel. to 13C when enriched

560

Linewidth parameter

1600 fm4

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References

C. Hall, "Application of chlorine, bromine, and iodine NMR spectroscopy to the study of physicochemical processes in liquids", Q. Rev., Chem. Soc., 25, 87-109 (1971).

"NMR, Basic Principles and Progress, Vol. 12: Chlorine, Bromine and Iodine NMR. Physico-Chemical and Biological Applications", P. Diehl, E. Fluck, and R. Kosfeld, Eds., Springer Verlag, 368 pp. (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).

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Updated 2007-02-05 © Roy Hoffman, Hebrew University 1996-2007