Ce₅Au_xGe_4-x [x = 0.43 (2)] with the orthorhombic Sm₅Ge₄ structure type

Single crystals of the title compound, penta­cerium gold tetra­germanium, were synthesized from the corresponding elements using a eutectic Au/Ge mixture as solvent. Structure determination of a crystal from that reaction revealed the composition Ce₅Au_xGe_4-x (x = 0.43). The compound is a new ternary derivative of the Sm₅Ge₄ structure type that crystallizes in the space group Pnma of the orthorhombic system. There are six atoms in the asymmetric unit, one Ce in Wyckoff site 4c, two Ce in 8d, two Ge in 4c and one Ge in 8d. Two of the Ge sites are statistically occupied by Ge and Au atoms, with a lack of long-range ordering. The results are consistent with an earlier report on the structure of the fully stoichiometric analog Ce₅Ge₄.

PrCu_5-xIn_1+x [x = 0.24 (1)] with the orthorhombic CeCu₆ structure type

Large single crystals of the title compound were synthesized from the corresponding elements using an eutectic Cu/In mixture as a solvent. PrCu_5-xIn_1+x [x = 0.24 (1)] is a new ternary derivative of the orthorhombic CeCu₆ structure type [space group Pnma (No. 62)]. This result contradicts the findings of Kalychak et al. [(1988). Dop. Akad. Nauk Ukr. RSR Ser. B, 9, 39-42], who found that CeCu_4.38In_1.62 belongs to a new structure type (space group Pnnm), derived from the parent CeCu₆ compound by doubling the a axis. In the present structure, all the atoms except one of the Cu species occupy special positions with mirror symmetry.

CeCu_5-xIn_1+x [x = 0.17 (1)] with the orthorhombic CeCu₆ structure

Large single crystals of the title compound, cerium copper indium, were synthesized from the elements using a eutectic Cu/In mixture as a solvent. CeCu_5-xIn_1+x [x = 0.17 (1)] is a new ternary derivative of the orthorhombic CeCu₆ structure type [space group Pnma (No. 62)]. This result differs from that of Kalychak, Baranyak, Belsky & Dmytrakh [Dopl. Akad. Nauk Ukr. RSR Ser. B (1988). 9, 39-42], who found that CeCu_4.38In_1.62 belongs to a new structure type (space group Pnnm), derived from the parent CeCu₆ compound by doubling the a axis. In the present structure, all the atoms, except one of the Cu species, occupy special positions with mirror symmetry.

YbAg_xSi_2−x [x = 0.28 (1)] with the tetragonal α-ThSi₂ structure type

Single crystals of the title compound, ytterbium silver silicide, were synthesized from the corresponding elements using a eutectic Ag/Si mixture as a solvent. Structure determination suggested the composition of the product to be YbAg_xSi_2−x [x = 0.28 (1)], i.e. a new ternary derivative of the α-ThSi₂ structure type, which crystallizes in the body-centered tetragonal space group I4₁/amd. The two atoms in the asymmetric unit lie on special positions with Wyckoff symbols 4a (Yb), and 8e (disordered Ag and Si).