Abstract
Samples of a layered α-Sn (IV) phosphate were partially deuterated by soaking with D(2)O to yield a mixture of two isotopomers Sn (HPO(4)) (DPO(4)).c-H(2)O and Sn (DPO(4))(2).c-H(2)O containing cavity water c-H(2)O. They were characterized by the (1)H, (2)H, (31)P, and (119)Sn MAS NMR experiments including relaxation time measurements. The formation of these isotopomers is proven by the kinetic proton-deuterium cross-polarization MAS NMR experiments giving the cross-polarization rate constant T(H-D) of 3.2 ms. In agreement with their formulation the (2)H MAS NMR spectra of Sn (HPO(4)) (DPO(4)).c-H(2)O and Sn (DPO(4))(2).c-H(2)O did not display the other signals besides the DPO(4) resonance. The DPO(4) groups observed in the temperature-independent (2)H MAS NMR spectra show the DQCC value of 184 ± 6 kHz corresponding to hydrogen bonds formed with an O(…) O distance estimated as ~2.7 Å. Because of reduced dipolar interactions in the deuterated samples, the (1)H MAS NMR spectra are well resolved providing signal assignments and the analysis. According to the solid-state NMR data collected for the partially deuterated samples of SnP, the cavity water accepts one hydrogen bond from the P-OH donor group and forms one hydrogen bond with the neighboring phosphate group, while the other water hydrogen is not involved in hydrogen bonding.