Vanadium-51 nuclear magnetic resonance

Vanadium-51 nuclear magnetic resonance (⁵¹V NMR spectroscopy) is a method for the characterization of vanadium-containing compounds and materials. ⁵¹V comprises 99.75% of naturally occurring vanadium. The nucleus is quadrupolar with I = 7/2, which is not favorable for NMR spectroscopy, although its quadrupole moment and thus the linewidths are unusually small, while its magnetogyric ratio is relatively high (+7.0492 rad T⁻¹s⁻¹), so that ⁵¹V has 38% receptivity vs ¹H. Its resonance frequency is close to that of ¹³C (gyromagnetic ratio = 6.728284 rad T⁻¹s⁻¹).

The chemical shift dispersion is great as illustrated by this series: 0 for VOCl₃ (chemical shift standard), −309 for VOCl₂(O-i-Pr), −506 VOCl(O-i-Pr)₂, and −629 VO(O-i-Pr)₃. For vanadates, the parent orthovanadate and its conjugate acid absorb at −541 ([VO₄]^3-) and 534 ([HVO₄]^2-). For decavanadate, three shifts are observed in accord with the number of nonequivalent sites: −422, −502, −519.[1][2]

References

Rehder, D.; Polenova, T.; Bühl, M. (2007). Vanadium-51 NMR. Annual Reports on NMR Spectroscopy. Vol. 62. pp. 49–114. doi:10.1016/S0066-4103(07)62002-X. ISBN 9780123739193.
Howarth, Oliver W. (1990). "Vanadium-51 NMR". Progress in Nuclear Magnetic Resonance Spectroscopy. 22 (5): 453–485. doi:10.1016/0079-6565(90)80007-5.

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[1] Rehder, D.; Polenova, T.; Bühl, M. (2007). Vanadium-51 NMR. Annual Reports on NMR Spectroscopy. Vol. 62. pp. 49–114. doi:10.1016/S0066-4103(07)62002-X. ISBN 9780123739193.

[2] Howarth, Oliver W. (1990). "Vanadium-51 NMR". Progress in Nuclear Magnetic Resonance Spectroscopy. 22 (5): 453–485. doi:10.1016/0079-6565(90)80007-5.