title: Novel corrugated In9 anionic layer in Li2Y5In9: square pyramidal In5 clusters interconnected by unusual butterfly In4 clusters.
abstract: The new ternary polar intermetallic phase, Li2Y5In9, was obtained by high-temperature solid-state reactions of the corresponding elements inwelded Ta tubes. Its crystal structure was established by a single-crystal X-ray diffraction study. Li2Y5In9 crystallizes in the tetragonal space group P4/nmm (No. 129) with cell parameters of a = b = 10.1242(4), c = 15.1091(10) A and Z = 4. The structure of Li2Y5In9 features a two-dimensional corrugated anionic In9 layer composed of two types of square pyramidal In5 units and butterfly In4 units. There are two types of square pyramidal In5 units: one with normal In-In bonds and another one with greatly elongated In-In separations within its In4 square. Packing of these 2D In9 layers resulted in cavities and tunnels that are occupied by Y and Li atoms. Extended-Hückel tight-binding calculations indicate that Li2Y5In9 is metallic.
authors.affiliation: State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences and the Graduate School of Chinese Academy of Sciences, Fuzhou 350002, P. R. China.
authors.forename: Zhong-Ming
authors.initials: ZM
authors.lastname: Sun
authors.forename: Jiang-Gao
authors.initials: JG
authors.lastname: Mao
authors.forename: Da-Chun
authors.initials: DC
authors.lastname: Pan