The First Observation of Heteronuclear Two-BondJ-Coupling in the Solid State: Crystal Structure and Solid-State NMR Spectroscopy of Rb4(NbO)2(Si8O21)

Abstract

High-temperature, high-pressure hydrothermal synthesis of the title compound and its ⁹³Nb and ²⁹Si MAS NMR spectra are reported. The ²⁹Si MAS NMR spectrum shows four signals corresponding to the four distinct Si sites in the structure. Three signals show multiplet patterns which arise from ⁹³Nb(spin-⁹/₂)−²⁹Si J-coupling. This is the first example of two-bond J-coupling between a quadrupolar nucleus and a spin-¹/₂ nucleus in the solid state. A combination of ⁹³Nb and ²⁹Si solid-state NMR and X-ray diffraction data has provided a correlation between NMR interaction parameters and local structure. This work opens a new opportunity to examine the relationship between ²J-coupling and structural parameters in the solid state.