A B C
Z. Naturforsch. 2014, 69b, 851 – 858
doi:10.5560/ZNB.2014-4074
A Structural Comparison of Two Thallium Copper Erbium Sulfides: TlCu3Er2S5 and Tl2Cu5Er3S8
Marcel A. Eberle1, Jean-Marie Babo2 and Thomas Schleid1
1 University of Stuttgart, Institute for Inorganic Chemistry, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
2 Department of Civil Engineering and Geological Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
Reprint requests to Prof. Dr. Th. Schleid. E-mail: schleid@iac.uni-stuttgart.de
Received April 8, 2014 / published online August 12, 2014
Orange TlCu3Er2S5 crystallizes in the orthorhombic space group Cmcm (a = 391.27(2), b = 1382.91(7), c = 1630.54(8) pm, Z = 4). Its crystal structure contains one Tl+, one Er3+, two Cu+, and three S2− ions as crystallographically unique components. All Cu+ cations are coordinated by four S2− anions to form [CuS4]7− tetrahedra, which have vertex- and edge-connectivity to build up 2{[Cu3S5]7−} layers parallel to the (010) plane. The Er3+ cations are octahedrally surrounded by six S2− anions. These [ErS6]9− units share trans-oriented edges forming linear chains, which are further linked by common vertices yielding 1{[Er2S10]14−} double strands. Further fusion via common vertices results in 2{[Er2S5]4−} layers parallel to the (010) plane. Alternatingly stacked along [010] and condensed via S2− anions, these two types of layers form a three-dimensional framework, leaving tunnels along [100], where the Tl+ cations fit in. These are each coordinated by eight S2− anions in the shape of bicapped trigonal prisms. Tl2Cu5Er3S8 was obtained as black single crystals with metallic luster (monoclinic, Cm, a = 1381.69(7), b = 390.73(2), c = 1435.98(7) pm, β =111.132(3)°, Z = 2). Four of the five crystallographically different Cu+ cations are tetrahedrally surrounded by S2− anions, whereas (Cu3)+ is situated in sulfur triangles. Connected via common vertices and edges, the copper-sulfur polyhedra form strongly corrugated 2{[Cu5S8]11−} layers parallel to the (201̅) plane. All Er3+ cations are again coordinated by six S2− anions in the shape of [ErS6]9− octahedra. Their condensation via edges and vertices leads to 2{[Er3S8]7−} layers spreading out parallel to the (010) plane. Both types of anionic layers result in a three-dimensional framework through sulfide fusion, which leaves tunnels running along [010] occupied by Tl+ cations. The two crystallographically different Tl+ cations both have eight coordinating S2− anions forming bicapped trigonal prisms. Remarkably enough, the ion closest to (Tl1)+ is not a S2− anion (shortest Tl+–S2− bond: 305 pm), but a (Cu3)+ cation at a distance of just 291 pm.
Key words: Thallium, Copper, Erbium, Sulfides, Solid-State Crystal Structures
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