On phosphorus chemical shift anisotropy in metal (IV) phosphates and phosphonates: A 31P NMR experimental study

The phosphorus chemical shift anisotropies, P-31 Delta cs, and asymmetry parameters eta were measured by the P-31{H-1} NMR experiments in static and low-frequency spinning samples of the zirconium phosphates and phosphonates and also in the mixed Zr (IV)/Sn (IV) phosphate/phosphonate material. The data obtained have shown a 111 connectivity in the HPO4 and PO3 groups, which does not change at modification and intercalation of the materials. The P-31 Delta cs values of the phosphonate groups (43-49 ppm) significantly surpass the values characterizing the HPO4 groups (23-37 ppm). The P-31 Delta cs values obtained for the metal (IV) phosphates were discussed in terms of P-O distances. The P-31 chemical shift anisotropy parameters can help at elucidation of local structures in phosphate and phosphonate materials.