Synthesis, Crystal Structures, and Optical Properties of AM2(OH)(SeO3)2 (A = Na, Rb; M = Mg, Zn)

Sodium magnesium selenite NaMg 2 (OH)(SeO 3 ) 2 and rubidium zinc selenite RbZn 2 (OH)(SeO 3 ) 2 were prepared by hydrothermal reactions. The crystal structures of the title compounds were determined by single-crystal X-ray diffraction. NaMg 2 (OH)(SeO 3 ) 2 crystallizes in the orthorhombic space group Pnma (no. 62) with lattice parameters a = 13.1919(10), b = 6.0415(4), c = 8.2182(6) Å, and Z = 4 and RbZn 2 (OH)(SeO 3 ) 2 crystallizes in the triclinic space group P (no. 2) with lattice parameters a = 4.8698(5), b = 7.3446(8), c = 11.7796(12) Å, α = 82.554(3), β = 78.456(2), γ = 71.603(3)°,and Z = 2. The structure of NaMg 2 (OH)(SeO 3 ) 2 is a three-dimensional framework consisting of edge-sharing MgO 6 octahedra and trigonal pyramidal SeO 3 2– groups, whereas the structure of RbZn 2 (OH)(SeO 3 ) 2 is a two-dimensional layers structure consisting of corner-sharing [Zn 2 O 7 ] dimers linked by trigonal pyramidal SeO 3 2– groups. The compounds were characterized by the solid state UV/Vis/NIR diffuse reflectance, and FT-IR spectroscopy.