Münzmetall-Lanthanid-Chalkogenide: II. Kupfer(I)-Lanthanid(III)- Sulfide der Zusammensetzung CuMS2 (M = Dy – Lu) im orthorhombischen B-Typ / Coinage Metal Lanthanide Chalcogenides: II. Copper(I) Lanthanide(III) Sulfides of the Composition CuMS2 (M = Dy – Lu) with the Orthorhombic B-Type Structure

Abstract

Single crystals of the ternary copper(I) lanthanide(III) sulfides with the composition CuMS2 (M = Dy - Lu) are formed within seven days at 750 °C by oxidation of elemental copper and lanthanide metal with sulfur (molar ratio: 1 : 1 : 2, evacuated silica tubes) in equimolar quantities of CsCl, CsBr or CsI as fluxing agents. The CuYS2-type crystal structures (orthorhombic, Pnma, Z = 4; e. g. CuDyS2: a = 1342.51(9), b = 397.96(3), c = 627.43(5) pm and CuLuS2: a = 1315.06(9), b = 391.04(3), c = 624.18(5) pm) exhibit chains of cis edge-linked [CuS4]7− tetrahedra with the composition 1 ∞{[Cu(S1)3/3(S2)1/1]3−} which run parallel to [010] and show hexagonal rod packing. Charge compensation and three-dimensional interconnection of these anionic strands occur via octahedrally coordinated M3+ cations surrounded by six S2− anions. These [MS6]9− octahedra share vertices and edges to form a three-dimensional network 3 ∞{[M(S1)3/3(S2)3/3]−} with the ramsdellite-type topology of γ-MnO2. The metal sulfur distances within the [MS6] polyhedra are very similar (M-S: 263 - 279 pm), whereas those within the [CuS4] units cover the ranges 227 - 230 (Cu-S2) and 231 - 233 (Cu-S1) as well as 250 - 252 pm (Cu-S1′, 2×). The present work is the first comprehensive X-ray single crystal diffraction study of the complete isotypic B-type series CuMS2 (M = Dy - Lu).