ASb2(SO4)2(PO4) (A = H3O+, K, Rb): Layered Structure Containing Ordered Sulfate and Phosphate Anions

Three compounds A Sb 2 (SO 4 ) 2 (PO 4 ) ( A = H 3 O + , K, Rb) were obtained from the reactions of Sb 2 O 3 , A 2 CO 3 ( A = Li, Rb) or K 2 SO 4 and NH 4 H 2 PO 4 in H 2 SO 4 (98 %) at 220–250 °C. Their structures were determined by single-crystal X-ray diffraction. All compounds crystallize in the triclinic space group P (no.2) and are isostructural. The crystal structures consist of two-dimensional 2 ∞ [Sb 2 (SO 4 ) 2 (PO 4 )] – anionic layers and alkali cations, which are located between anionic layers. The anionic layers are composed of [SbO 4 ] ψ-trigonal bipyramids, [SbO 5 ] ψ octahedra, [SO 4 ] tetrahedra, and [PO 4 ] tetrahedra. All compounds are characterized by solid state UV/Vis/NIR diffuse reflectance spectra, FT-IR spectroscopy, and Raman spectroscopy.