Cu 3(SeO4)2(SeO3OH)2(H2O)16 -The First Example of a Linear Octahedral--Tetrahedral Heptamer in InorganicCompounds. -Single crystals of the new copper selenate Cu 3(SeO4)2(SeO3OH) 2(H2O)16 are obtained by hydrothermal reaction of an aqueous solution of (UO2)NO3, Cu(NO3)2, and H2SeO4 (autoclave, 180 C, 72 h) followed by slow solvent evaporation. The compound crystallizes in the triclinin space group P1 with Z = 1. The title heptamers are formed by successive polymerization of two SeO 3OH tetrahedra, two SeO4 tetrahedra, and three Cu(H2O)4O2 octahedra. The octahedra and tetrahedra are linked in trans-configuration which is in agreement with the Jahn-Teller distortion of the octahedral coordination geometry of Cu 2+ . -(GURZHIY, V. V.; AL-SHURAY, A.; BRITVIN, S. N.; KRIVOVICHEV*, S. V.; Eur. J. Inorg. Chem. 2015, 32, 5311-5313, http://dx.