YTlSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. Y(1) is bonded to six equivalent Se(1) atoms to form YSe6 octahedra that share corners with six equivalent Tl(1)Se6 octahedra, edges with six equivalent Y(1)Se6 octahedra, and edges with six equivalent Tl(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 10°. Tl(1) is bonded to six equivalent Se(1) atoms to form distorted TlSe6 octahedra that share corners with six equivalent Y(1)Se6 octahedra, edges with six equivalent Y(1)Se6 octahedra, and edges with six equivalent Tl(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 10°. Se(1) is bonded to three equivalent Y(1) and three equivalent Tl(1) atoms to form a mixture of distorted corner and edge-sharing SeY3Tl3 octahedra. The corner-sharing octahedra are not tilted.
YTlSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. Y(1) is bonded to six equivalent Se(1) atoms to form YSe6 octahedra that share corners with six equivalent Tl(1)Se6 octahedra, edges with six equivalent Y(1)Se6 octahedra, and edges with six equivalent Tl(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 10°. All Y(1)-Se(1) bond lengths are 2.88 Å. Tl(1) is bonded to six equivalent Se(1) atoms to form distorted TlSe6 octahedra that share corners with six equivalent Y(1)Se6 octahedra, edges with six equivalent Y(1)Se6 octahedra, and edges with six equivalent Tl(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 10°. All Tl(1)-Se(1) bond lengths are 3.32 Å. Se(1) is bonded to three equivalent Y(1) and three equivalent Tl(1) atoms to form a mixture of distorted corner and edge-sharing SeY3Tl3 octahedra. The corner-sharing octahedra are not tilted.