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, lanthanum salts may be toxic besides toxicity arising from the anion: wear protective gloves.

Lanthanum NMR

Lanthanum (La) has two quadrupolar NMR active nuclei ¹³⁸La and ¹³⁹La (fig. 1). They yield broad signals in symmetric environments and very broad signals in small complexes. The signals from larger complexes are too broad to be observed with a high-resolution NMR spectrometer. ¹³⁹La is medium sensitivity nucleus and much more sensitive than the very low sensitivity ¹³⁸La. ¹³⁸La also yields broader signals. Therefore ¹³⁹La is the lanthanum nucleus of choice. Lanthanum has a very wide chemical shift range. Lanthanum NMR is used for studying small lanthanum complexes and its relaxation rate is used in studies of binding.

Fig. 1. Comparison of ¹³⁸La and ¹³⁹La NMR for LaCl₃ (0.01 M) in D₂O. The experimental conditions were different for each nucleus so the ¹³⁹La signal should be about 1000 times more sensitive than it appears as compared with the ¹³⁸La signal.

Each type of lanthanum has its characteristic chemical shift range (fig. 2).

Fig. 2. Chemical shift ranges for lanthanum NMR

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¹³⁸Lanthanum NMR

¹³⁸La (fig. 3) yields signals that are broader and much less sensitive and than ¹³⁹La. Therefore ¹³⁸La is not the lanthanum nucleus of choice for NMR.

Fig. 3. ¹³⁸La NMR spectrum of LaCl₃ (0.01 M) in D₂O

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Properties of ¹³⁸La

(Click here for explanation)

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¹³⁹Lanthanum NMR

¹³⁹La (fig. 4) yields signals that are less broad and much more sensitive and than ¹³⁸La. Therefore ¹³⁹La is the lanthanum nucleus of choice for NMR.

Fig. 4. ¹³⁹La NMR spectrum of LaCl₃ (0.01 M) in D₂O

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Properties of ¹³⁹La

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References

1. O. Lutz, and H. Oehler, "Lanthanum-138 and lanthanum-139 nuclear magnetic resonance studies", J. Magn. Reson., 37, 261-267 (1980).
2. V. P. Tarasov, G. A. Kirakosyan, Y. A. Buslaev, S. V. Trots, and V. T. Panyushkin, "Lanthanum-139 NMR study of aqueous dimethylformamide solutions", Koordinat. Khim., 11, 913-917 (1985).
3. S. H. Eggers, and R. D. Fischer, "Preparation and lanthanum-139 NMR characterization of tris(cyclopentadienyl)bis(cyclohexyl isonitrile) lanthanum (III)", J. Organometal. Chem., 315, C61-C63 (1986).
4. M. Adam, E. T. K. Haupt, and R. D. Fischer, "Lanthanum-139 NMR spectroscopy of organolanthanum(III) complexes. Part IV. Lanthanum-139 NMR : investigations on organolanthanum compounds", Bull. Magn. Reson., 12, 101-103 (1990).
5. A. F. Savost'yanova, V. V. Trachevskii, and V. S. Kuts, "Magnetic resonance characteristics of lanthanum dithiocarbamates" Koordinat. Khim., 17, 417-421 (1991).
6. H. Windisch, J. Scholz, R. Taube and B. Wrackmeyer, "¹³⁹La-NMR-spectroscopy of allyl lanthanum (III) complexes", J. Organometal. Chem., 520, 23-30 (1996).
7. Y. Israeli, and C. Detellier, "Multinuclear magnetic resonance study of the complexation of lanthanum (III) by D-glucitol and ribitol in aqueous solution", Carbohyd. Res., 297, 201-207 (1997).
8. T. Yaita, D. Ito and S. Tachimori, "¹³⁹La NMR relaxation and chemical shift studies in aqueous nitrate and chloride solutions", J. Phys. Chem. B, 102, 3886-3891 (1998).

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