Yb{sub 3}CoSn{sub 6} and Yb{sub 4}Mn{sub 2}Sn{sub 5}: New polar intermetallics with 3D open-framework structures

Two new ternary ytterbium transition metal stannides, namely, Yb{sub 3}CoSn{sub 6} and Yb{sub 4}Mn{sub 2}Sn{sub 5}, have been obtained by solid-state reactions of the corresponding pure elements in welded tantalum tubes at high temperature. Their crystal structures have been established by single-crystal X-ray diffraction studies. Yb{sub 3}CoSn{sub 6} crystallizes in the orthorhombic space group Cmcm (no. 63) with cell parameters of a=4.662(2), b=15.964(6), c=13.140(5) A, V=978.0(6) A{sup 3}, and Z=4. Its structure features a three-dimensional (3D) open-framework composed of unusual [CoSn{sub 3}] layers interconnected by zigzag Sn chains, forming large tunnels along the c-axis which are occupied by the ytterbium cations. Yb{sub 4}Mn{sub 2}Sn{sub 5} is monoclinic space group C2/m (no. 12) with cell parameters of a=16.937(2), b=4.5949(3), c=7.6489(7) A, {beta}=106.176(4){sup o}, V=571.70(8) A{sup 3}, and Z=2. It belongs to the Mg{sub 5}Si{sub 6} structure type and its anionic substructure is composed of parallel [Mn{sub 2}Sn{sub 2}] ladders interconnected by unusual zigzag [Sn{sub 3}] chains, forming large tunnels along the c-axis, which are filled by the ytterbium cations. Band structure calculations based on density function theory methods were also made for both compounds. - Graphic abstract: Yb{sub 3}CoSn{sub 6} and Yb{sub 4}Mn{sub 2}Sn{sub 5} have been prepared and structurally characterized.more » Yb{sub 3}CoSn{sub 6} features a 3D open-framework composed of novel [CoSn{sub 3}] layers interconnected by the zigzag Sn chains whereas the anionic substructure of Yb{sub 4}Mn{sub 2}Sn{sub 5} is composed of parallel [Mn{sub 2}Sn{sub 2}] ladders interconnected by the unusual one-dimensional (1D) chains formed by linear [Sn{sub 3}] trimers.« less