A Bismuth‐Stabilized Metal‐Rich Telluride Lu 9 Bi ≈1.0 Te ≈1.0 – Synthesis and Characterization

Synthetic reactions aimed at bismuth incorporation into rare‐earth‐metal‐rich tellurides yielded Lu 9 Bi ≈1.00 Te ≈1.00 over a small range of compositions, but no analogues with Gd, Tb, Er, or Y. A single‐crystal X‐ray diffraction analysis gave the composition Lu 9 Bi 0.99(3) Te 1.01 in the acentric orthorhombic space group Cmc 2 1 at ambient temperature. This is isostructural with the re‐refined Sc 9 Te 2 earlier reported in a monoclinic Cc structure. Lu 9 Bi ≈1.00 Te ≈1.00 represents the first ternary compound in this structure type and the third lutetium‐richest compound after Lu 8 Te and Lu 7 Te. The structure contains 3 × 3 columns of Lu in the form of condensed distorted trans ‐edge‐sharing octahedral chains along a . The Te and Bi anions lie within tricapped trigonal prisms of Lu. Generally shorter Lu–Lu interactions lie in the interior of 3 × 3 metal columns compared with those on the periphery for which fewer Lu–Lu interactions and polar covalent bonding with neighboring tellurium weaken Lu–Lu bonding. Limiting Lu–Lu distances around 3.18 Å are by far the shortest among reduced lutetium tellurides. LMTO‐type ab initio electronic structure calculations reveal a metallic nature and show that strong polar bonding of Lu to both the more electronegative Bi and Te leaves Lu relatively oxidized, many 5 d states falling above the Fermi level. Stronger Lu–Lu bonding within the metal columns is also indicated by their larger individual Hamilton populations. The isostructural Lu 9 SbTe and Sc 9 BiTe were also shown to exist according to powder data.