A P-31 spin diffusion and P-31-Cd-113 CP/MAS NMR study of polycrystalline Cd-3(PO4)(2)

Two-dimensional P-31 spin diffusion MAS NMR experiments on polycrystalline Cd-3(PO4)(2), using a broadbanded dipolar recoupling scheme, are reported. Quantitative analysis of the P-31 spin diffusion experiments as a function of mixing times yields unambiguous assignment of the six P-31 resonances to the six independent crystallographic P sites in the asymmetric unit of solid Cd-3(PO4)(2). Internuclear P-P connectivities determined from these P-31 Spin diffusion MAS NMR experiments quantitatively agree with the P-P distance connectivities as determined by single-crystal X-ray diffraction. On the basis of the known assignment of all P-31 resonances for Cd-3(PO4)(2), all Cd-113 resonances can be unambiguously assigned to the respective nine independent crystallographic Cd sites, using one-dimensional selective P-31 --> Cd-113 CP/MAS NMR techniques where a P-31 chemical shift filter is used as a preparation step for selective P-31 --> Cd-113 cross-polarization.