Hydrogen Bonding Network in Interlayer Spaces of a Partially Deuterated Layered α‐Sn (IV) Phosphate: A Solid‐State MAS NMR Study

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.