Vanadium-51 nuclear magnetic resonance (<sup>51</sup>V NMR spectroscopy) is a method for the characterization of vanadium-containing compounds and materials. <sup>51</sup>V comprises 99.75% of naturally occurring vanadium. The nucleus is quadrupolar with I = , 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<sup>âÂÂ1</sup>s<sup>âÂÂ1</sup>), so that <sup>51</sup>V has 38% receptivity vs <sup>1</sup>H. Its resonance frequency is close to that of <sup>13</sup>C (gyromagnetic ratio = 6.728284 rad T<sup>âÂÂ1</sup>s<sup>âÂÂ1</sup>).
The chemical shift dispersion is great as illustrated by this series: 0 for VOCl<sub>3</sub> (chemical shift standard), âÂÂ309 for VOCl<sub>2</sub>(O-i-Pr), âÂÂ506 VOCl(O-i-Pr)<sub>2</sub>, and âÂÂ629 VO(O-i-Pr)<sub>3</sub>. For vanadates, the parent orthovanadate and its conjugate acid absorb at âÂÂ541 ([VO<sub>4</sub>]<sup>3-</sup>) and 534 ([HVO<sub>4</sub>]<sup>2-</sup>). For decavanadate, three shifts are observed in accord with the number of nonequivalent sites: âÂÂ422, âÂÂ502, âÂÂ519.