Synthesis and Crystal Structure of Sm Cu7.73In3.27: a New 3D Framework Based on [Cu5In4M4](M=Cu/In) Cluster

A new intermetallic compound, SmC u7.73In3.27, has been synthesized by solid-state reaction of the corresponding pure elements at high temperature, and structurally characterized by single-crystal X-ray diffraction study. SmC u7.73In3.27 crystallizes in tetragonal space group P4/mbm with a = 8.6213(4), c = 10.2538(9), V = 762.13(8) A3, Z = 4, Mr = 1018.90, Dc = 8.880 g/cm3, μ =38.244 mm-1, F(000) = 1789, and the final R = 0.0374 and w R = 0.0836 for 514 observed reflections with I > 2σ(I). The structure of SmC u7.69In3.31 belongs to a new structure type and features a three-dimensional(3D) [Cu5In2M4](M = Cu/In) framework composed of [Cu5In4M4] clusters interconnected via sharing In atoms as well as Cu–In and In–In bonds. The Sm atoms are located in the one-dimensional(1D) tunnels along the c-axis. The structural relationship of the title compound with other similar Sm-Cu-In phases was also studied. Band structure calculations based on Density Functional Theory(DFT) method indicate that SmC u7.69In3.31 is metallic.