Kinetics of ¹H ³¹P NMR cross-polarization and dynamics in a layered crystalline -Sn(IV) phosphate

The proton-phosphorus (H-P) cross-polarization (CP) is effective in Sn(HPO4)(2)center dot H2O despite of the presence of paramagnetic ion impurities. Polarization constants TH-P and H-1 T-1 rho times are measured in static Sn(HPO4)(2)center dot H2O by the kinetic variable-temperature H-P CP experiments. The temperature dependence of the H-1 T-1 rho times is interpreted in terms of proton movements in the interlayer space occurring between the phosphate groups without participation of the water molecules. The process requires an activation energy of 8.7 +/- 0.7 kcal/mol. The MAS effect on the H-1 T-1 rho times is shown and discussed.