Through-bond indirect and through-space direct dipolar coupling 31P MAS NMR constraints for spectral assignment in the cubic 3 x 3 x 3 superstructure of Ti2O7

A P-31 solid-state NMR study of TiP2O7 is reported. The combined constraints from one-dimensional P-31 MAS NMR experiments and from P-31 2D MAS NMR experiments probing through-bond P-O-P connectivities via homonuclear J coupling interactions (TOBSY experiments), positively identify the cubic space group Pa(3) over bar with a 3 x 3 x 3 superstructure. Additional P-31 2D MAS NMR experiments, probing spatial connectivities between phosphorus sites via homonuclear dipolar coupling interactions (P-31 single-quantum-double-quantum correlation MAS NMR experiments), subsequently lead to complete assignment of the ii distinct crystallographic P sites in the structure of TiP2O7 to the corresponding eight resolved resonances in P-31 MAS NMR spectra of TiP2O7, while P-31 RIL ZQT and C7 DQT MAS NMR experiments confirm that TiP2O7 and the cubic phase of SiP2O7 are isostructural.