Rb3In(H2O)Si5O13: A Novel Indium Silicate with a CdSO4-Topological-Type Structure

A novel indium silicate, Rb 3 In(H 2 O)Si 5 O 1 3 , has been synthesized using a high-temperature, high-pressure hydrothermal method and characterized by single-crystal X-ray diffraction. The structure consists of five-membered rings of corner-sharing SiO 4 tetrahedra connected via corner sharing to four adjacent five-membered rings to form a 3D silicate framework that belongs to the CdSO 4 topological type. The InO 6 octahedron shares five of its corners with five different SiO 4 tetrahedra to form a 3D framework that delimits two types of channels to accommodate the rubidium cations. The sixth corner of InO 6 is coordinated H 2 O. The structure is related to that of the titanium silicate ETS-10, and these are the only two metal silicates that have the CdSO 4 -topological-type structure. In addition, the crystal of Rb 3 In(H 2 O)-Si 5 O 1 3 shows an intense second harmonic generation signal. Crystal data: H 2 Rb 3 inSi 5 O 1 4 , monoclinic, space group Cc (No. 9), a = 9.0697(5) A, b = 11.5456(6) A, c = 13.9266(8) A, β = 102.300(1)°, V = 1424.8(1) A 3 , and Z= 4.