NdClSeO3 and ErClSeO3: First Chloride-Selenites of the Rare Earth Elements

Abstract

Violet single crystals of NdClSeO3 (Pnma, Z = 8, a = 1115.3(2), b = 535.19(6), c = 1356.8(1) pm, Rall = 0.0281) were obtained from the reaction of Nd2O3, NdCl3, and SeO2 in evacuated silica ampoules. The analogous procedure using Er2O3 and ErCl3 led to pink single crystals of ErClSeO3 (Pnma, Z = 4, a = 721.8(1), b = 692.2(1), c = 874.3(2) pm, Rall = 0.0305). The crystal structure of NdClSeO3 contains two crystallographically different neodymium ions. Nd(2)3+ is coordinated by four oxygen atoms and four chloride ions while eight oxygen atoms and one Cl− ion are connected to Nd(1)3+. The linkage of the polyhedra leads to a three-dimensional structure. In the structure of ErClSeO3 the Er3+ ion is coordinated by two Cl− ions, three O-monodentate SeO3 2− and one O,O-chelating SeO3 2− groups. The [ErO5Cl2] polyhedra can be seen as pentagonal bipyramids, which are connected in the [010] direction via opposite edges of oxygen atoms to infinite chains. These are further linked via chloride ions to give a three-dimensional network. In both crystal structures a prominent stereochemical activity of the lone electron pairs of the selenite ions can be observed.