Synthesis, crystal and electronic structure of BaLi Cd ( ≈ 2).

A new ternary phase has been synthesized and structurally characterized. BaLi Cd ( ≈ 2) adopts the cubic NaZn structure type (space group , Pearson symbol 112) with unit cell parameter = 13.5548 (10) Å. Structure refinements from single-crystal X-ray diffraction data demonstrate that the Li atoms are exclusively found at the centers of the Cd-icosahedra. Since a cubic BaCd phase does not exist, and the tetragonal BaCd is the most Cd-rich phase in the Ba-Cd system, BaLi Cd ( ≈ 2) has to be considered as a true ternary compound. As opposed to the typical electron count of ca. 27-per formula unit for many known compounds with the NaZn structure type, BaLi Cd ( ≈ 2) only has ca. 26-, suggesting that both electronic and geometric factors are at play. Finally, the bonding characteristics of the cubic BaLi Cd ( ≈ 2) and tetragonal BaCd are investigated using the TB-LMTO-ASA method, showing metallic-like behavior.