HoTlSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. Ho(1) is bonded to six equivalent Se(1) atoms to form HoSe6 octahedra that share corners with six equivalent Tl(1)Se6 octahedra, edges with six equivalent Ho(1)Se6 octahedra, and edges with six equivalent Tl(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 11°. Tl(1) is bonded to six equivalent Se(1) atoms to form distorted TlSe6 octahedra that share corners with six equivalent Ho(1)Se6 octahedra, edges with six equivalent Ho(1)Se6 octahedra, and edges with six equivalent Tl(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 11°. Se(1) is bonded to three equivalent Ho(1) and three equivalent Tl(1) atoms to form a mixture of distorted edge and corner-sharing SeHo3Tl3 octahedra. The corner-sharing octahedra are not tilted.
HoTlSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. Ho(1) is bonded to six equivalent Se(1) atoms to form HoSe6 octahedra that share corners with six equivalent Tl(1)Se6 octahedra, edges with six equivalent Ho(1)Se6 octahedra, and edges with six equivalent Tl(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 11°. All Ho(1)-Se(1) bond lengths are 2.86 Å. Tl(1) is bonded to six equivalent Se(1) atoms to form distorted TlSe6 octahedra that share corners with six equivalent Ho(1)Se6 octahedra, edges with six equivalent Ho(1)Se6 octahedra, and edges with six equivalent Tl(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 11°. All Tl(1)-Se(1) bond lengths are 3.32 Å. Se(1) is bonded to three equivalent Ho(1) and three equivalent Tl(1) atoms to form a mixture of distorted edge and corner-sharing SeHo3Tl3 octahedra. The corner-sharing octahedra are not tilted.