Abstract: | The new compounds M3Fe2(SeO3)6 (M = Ca, Sr) were obtained as crystalline precipitates from aqueous solutions of the respective ions, kept in Teflon-coated vessels at a temperature of 227(2)°C for several days. The crystal data are: space group R3 c, a = 8.531(2), 8.802(2) Å; c = 38.89(1), 39.00(1) Å; V = 2451.1, 2616.7 Å3, Z = 6. The crystal structures have been refined by single-crystal X-ray diffraction methods to R1 = 0.021, 0.023; wR2 = 0.038, 0.039. The framework structure is built up by two types of FeO6 octahedra as well as by MO8 groups and SeO3 trigonal pyramids by corner- and edge-linkage of the polyhedra. |