⁵¹V NMR studies of crystalline monovalent and divalent metal metavanadates

⁵¹V static and magic-angle spinning (MAS) NMR spectra of crystalline monovalent metal metavanadates LiVO₃, α- and βNaVO₃, KVO₃, CsVO₃, β-AgVO₃, and NH₄VO₃ and divalent metal metavanadates M(VO₃)₂ (M = Mg, Ca, Sr, Ba, Zn, Pb) have been measured in order to establish the relationships between the various NMR parameters, such as isotropic chemical shift, δ_iso, chemical shift anisotropy, |Δ;δ|, the asymmetry parameter, η, and the crystallographic parameters. When the structural units are the same, in this case VO₄ tetrahedra or VO₅ trigonal bipyramids, the δ_iso decrease almost linearly with decreasing average V-O bond length, independent of the polymerization degree and linkage mode of the VO_n polyhedra. |Δ;δ|, increases with the polymerization degree and the degree of the structural distortion of the VO_n polyhedron. It is found possible to predict the structural unit and the polymerization degree on the basis of the relation between |Δ;δ| and η.