High-Pressure Synthesis and Structure Determination of K₆(SeO₄)(SeO₅), the First Potassium Orthoselenate(VI)

Abstract

We report on the first synthesis of a potassium orthoselenate(VI), K6(SeO4)(SeO5), and the structure determination from synchrotron powder diffraction data. The title compound crystallizes in the tetragonal space group P41212 with a = 8.1259(1) A, c = 17.4953(2) A, V = 1155.21(2) A3, and Z = 4. Selenium displays two different complex anions, tetrahedral SeO42- and trigonal-bipyramidal SeO54-. When the formula is reduced to A3B, the spatial arrangement of the constituting building units can be derived from the Li3Bi type of structure.