Sc2Se3O9: Scandium(III) Oxoselenate(IV) According to Sc2[SeO3]3 with a Hexagonal "Lone‐Pair" Channel Structure

Abstract

AbstractThe colourless title compound scandium(III) oxoselenate‐(IV) Sc2Se3O9 (≡Sc2[SeO3]3) was obtained by reacting a 1:3‐molar mixture of Sc2O3 and SeO2 at 830°C for seven days in an evacuated torch‐sealed silica vessel as needle‐shaped single crystals. It crystallizes hexagonally (space group: P63/m, Z = 2; a = 814.28(5), c = 764.56(4) pm, c/a = 0.939, Vm = 132.19 cm3/mol, R1 = 0.034 for 364 unique reflections) and exhibits Sc3+ cations in distorted trigonal antiprismatic coordination of six oxygen atoms (d(Sc‐O) = 202 ‐ 220 pm) all of which belong to six different isolated ψ1‐tetrahedral [SeO3]2‐ anions (d(Se‐O) = 166 ‐ 170 pm). In the crystal structure two [ScO6] octahedra share a common face to form a [Sc2O9] dimer (d(Sc···Sc) = 315 pm). The linkage of different dimers occurs only via common vertices with discrete trigonal non‐planar [SeO3]2‐ pyramids and the free non‐bonding electron pairs ("lone pairs") of the Se4+ cations occupy an empty hexagonal channel propagating along the [001] direction.