Sc 2 Te 5 O 13 und Sc 2 TeO 6 : Die ersten Oxotellurate des Scandiums

Sc 2 Te 5 O 13 and Sc 2 TeO 6 : The First Oxotellurates of Scandium Sc 2 Te 5 O 13 and Sc 2 TeO 6 are the first oxotellurates of scandium that could be structurally elucidated by X‐ray diffraction using single crystals. The scandium(III) oxotellurate(IV) Sc 2 Te 5 O 13 was synthesized by reacting Sc 2 O 3 with TeO 2 at 850 °C and crystallizes in the triclinic system with space group $P{\bar 1}$ (no. 2) and the lattice parameters a = 660.67(5), b = 855.28(7), c = 1041.10(9) pm, α = 86.732(8), β = 86.264(8), and γ = 74.021(8)° (Z = 2). The crystal structure contains chains respectively strands of alternatingly edge‐ and vertex‐sharing [ScO 6 ] 9− and [ScO 7 ] 11− polyhedra. These strands are connected by [TeO 3+1 ] (2+2)− oxotellurate(IV) anions. The coordination spheres of Sc 3+ appear markedly smaller than those of M 3+ cations in the other known compounds of the formula type M 2 Te 5 O 13 (M = Y, Dy – Lu), therefore Sc 2 Te 5 O 13 is not really isotypic, but only isopuntal with these compounds. Single crystals of the scandium(III) oxotellurate(VI) Sc 2 TeO 6 were obtained through the fusion of a mixture of Sc 2 O 3 and TeO 3 at 850 °C. It crystallizes trigonally ( a = 874.06(7), c = 479.85(4) pm and c / a = 0.549) with the Na 2 SiF 6 ‐type structure in space group P 321 (no. 150) and three formula units per unit cell. Its crystal structure is built up by a hexagonal closest packing ( hcp ) of oxide anions with the Sc 3+ cations residing in 1 / 3 and the Te 6+ cations in 1 / 6 of the octahedral interstices in a well‐ordered occupation pattern. Thus one can address the structural situation in Sc 2 [TeO 6 ] as a stuffed β ‐WCl 6 ‐type arrangement.