La6Pd13Cd4 and Ce6Pd 13Cd4 with palladium-centred rare earth octahedra: Synthesis, structure, and chemical bonding

Tappe F, Matar SF, Pöttgen R

Zusammenfassung

The palladium-rich cadmium compounds La6Pd13Cd4 and Ce6Pd13Cd4 were synthesized by induction melting the elements in sealed tantalum ampoules and subsequent annealing. They were characterized by X-ray powder and single-crystal diffraction: Na16Ba6N type, Im3m, a=988.12(9) pm, wR2=0.0463, 225 F 2 values, and 12 variables for La6Pd13Cd4, and a=982.1(2) pm, wR2=0.0521, 215 F 2 values, and 12 variables for Ce6Pd13Cd4. The striking structural motifs are palladium-centred La6 and Ce6 octahedra, which are packed in a bcc fashion. Further palladium and cadmium atoms built up three-dimensional [Pd3Cd] networks in which the La6Pd and Ce6Pd octahedra are embedded. Chemical bonding analyses show that the dominant interaction occurs within the palladium-centred RE 6 octahedra, while weaker bonding exists between them.