TlSmSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. Sm(1) is bonded to six equivalent Se(1) atoms to form SmSe6 octahedra that share corners with six equivalent Tl(1)Se6 octahedra, edges with six equivalent Sm(1)Se6 octahedra, and edges with six equivalent Tl(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 9°. Tl(1) is bonded to six equivalent Se(1) atoms to form distorted TlSe6 octahedra that share corners with six equivalent Sm(1)Se6 octahedra, edges with six equivalent Sm(1)Se6 octahedra, and edges with six equivalent Tl(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 9°. Se(1) is bonded to three equivalent Sm(1) and three equivalent Tl(1) atoms to form a mixture of distorted corner and edge-sharing SeSm3Tl3 octahedra. The corner-sharing octahedra are not tilted.
TlSmSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. Sm(1) is bonded to six equivalent Se(1) atoms to form SmSe6 octahedra that share corners with six equivalent Tl(1)Se6 octahedra, edges with six equivalent Sm(1)Se6 octahedra, and edges with six equivalent Tl(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 9°. All Sm(1)-Se(1) bond lengths are 2.94 Å. Tl(1) is bonded to six equivalent Se(1) atoms to form distorted TlSe6 octahedra that share corners with six equivalent Sm(1)Se6 octahedra, edges with six equivalent Sm(1)Se6 octahedra, and edges with six equivalent Tl(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 9°. All Tl(1)-Se(1) bond lengths are 3.33 Å. Se(1) is bonded to three equivalent Sm(1) and three equivalent Tl(1) atoms to form a mixture of distorted corner and edge-sharing SeSm3Tl3 octahedra. The corner-sharing octahedra are not tilted.