Characterization of the room-temperature structure of SnP2O7 by 31P through-space and through-bond NMR correlation spectroscopy

The room-temperature structure of SnP2O7 has been investigated using various one- and two-dimensional (1- and 2D) magic-angle spinning (MAS) NMR experiments. We show that P-31 homonuclear through-bond and through-space correlation NMR spectroscopies allow us to discriminate between the 12 possible space group symmetries of the structure. In particular, the P-31 2D refocused INADEQUATE experiment allows us to resolve an impressive number of distinct P-31 resonances, showing that the asymmetric unit contains at least 49 different P2O7 groups with two inequivalent P sites. The results suggest that the symmetry of the SnP2O7 room-temperature structure is monoclinic with space group P2(1) or Pc.