Synthesis and structure of perrhenate sodalite

Na8(AlSiO4)6(ReO4)2 sodalite was synthesized using a hydrothermal method and its crystal structure was determined from Rietveld refinement of experimental X-ray powder diffraction data. The refinement showed that this compound adopts the cubic sodalite structure (space group P4¯3n, #218) with a = 9.1528 (1) Å. Raman spectroscopic measurements confirm the presence of tetrahedral ReO4- groups. Broadening of the asymmetric stretching and bending vibrational modes suggests the tetrahedra are slightly distorted from ideal Td symmetry in the sodalite lattice. MAS NMR of 29Si and 27Al nuclei showed single intense peaks at δiso = −92.4 ppm and δiso = 57.5 ppm, respectively, confirming the alternating Si, Al tetrahedral ordering in sodalite deduced from the structural data. Chemical shifts for 29Si and 27Al calculated using correlative structural parameters (56.6 ± 0.8 ppm and −92.3 ± 0.9 ppm) showed good agreement with measured data indicating the validity of data derived from the Rietveld structural refinement.