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

## TL;DR

This study uses NMR to analyze hydrogen bonding in a partially deuterated layered tin phosphate material.

## Contribution

The paper reveals the hydrogen bonding network involving cavity water in a deuterated α-Sn(IV) phosphate structure.

## Key findings

- Cavity water accepts a hydrogen bond from a P-OH donor and forms one with a neighboring phosphate group.
- The O...O distance in hydrogen bonds is estimated to be ~2.7 Å based on NMR data.
- Deuteration reduces dipolar interactions, enabling clearer 1H NMR signal resolution and analysis.

## Abstract

Samples of a layered α‐Sn (IV) phosphate were partially deuterated by soaking with D2O to yield a mixture of two isotopomers Sn (HPO4) (DPO4).c‐H2O and Sn (DPO4)2.c‐H2O containing cavity water c‐H2O. They were characterized by the 1H, 2H, 31P, and 119Sn 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 2H MAS NMR spectra of Sn (HPO4) (DPO4).c‐H2O and Sn (DPO4)2.c‐H2O did not display the other signals besides the DPO4 resonance. The DPO4 groups observed in the temperature‐independent 2H 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 1H 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.

The solid‐state 1H and 2H NMR data collected for deuterated α‐Sn (HPO4)2 phosphate suggest the hydrogen bonding network, where 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.