A New Mixed Framework Compund with Corrugated [Si_6O_(15]infinity infinity Layers:K_2TiSi_6O_(15)

摘要

The hydrothermal reaction in an aqueous mixture of TiCl_3, colloidal silica, KF, and KOH yielded colorless prismatic crys-tals of K_2TiSi_6O_(15). The structure contains one unique TiO_6 octahedron and six unique SiO4 tetrahedra. The SiO_4 tetrahedra are corner-shared with each other, forming a corrugated [Si_6O_(15)] infinity infinity layer containing four-, six-, and eight-membered rings. These layers are connected by isolated TiO_6 octahedra into a three-dimensional octahedral-tetrahedral mixed anion frame-work.Four-, five-, and seven-membered rings are formed by mixed SiO_4 tetrahedra and TiO_6 octahedra. The two potassium cations are located in the cage formed by the six- and seven-membered rings. The structure of the title compound is com-pared with those of related silicates. Crystal data: monoclinic,space group P2_1, a = 6.916(3), b = 12.812(3), c = 7.661(2) A, #beta#=106.25(4)deg, V=651.7(4) A~3, Z= 2, and M= 534.64. R_F=0.0329 for 2565 unique reflections with I> 2#pi#(I) and 218 parameters.