Hg4CdSe5 is Caswellsilverite-like structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded to three equivalent Se(1) and three equivalent Se(3) atoms to form HgSe6 octahedra that share corners with three equivalent Hg(2)Se6 octahedra, corners with three equivalent Cd(1)Se6 octahedra, edges with three equivalent Hg(2)Se6 octahedra, edges with three equivalent Cd(1)Se6 octahedra, and edges with six equivalent Hg(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the second Hg site, Hg(2) is bonded to three equivalent Se(2) and three equivalent Se(3) atoms to form a mixture of corner and edge-sharing HgSe6 octahedra. The corner-sharing octahedra are not tilted. Cd(1) is bonded to six equivalent Se(1) atoms to form CdSe6 octahedra that share corners with six equivalent Hg(1)Se6 octahedra, edges with six equivalent Hg(1)Se6 octahedra, and edges with six equivalent Cd(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 1°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Hg(1) and three equivalent Cd(1) atoms to form SeCd3Hg3 octahedra that share corners with three equivalent Se(1)Cd3Hg3 octahedra, corners with three equivalent Se(3)Hg6 octahedra, edges with three equivalent Se(3)Hg6 octahedra, and edges with nine equivalent Se(1)Cd3Hg3 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the second Se site, Se(2) is bonded to six equivalent Hg(2) atoms to form a mixture of corner and edge-sharing SeHg6 octahedra. The corner-sharing octahedra are not tilted. In the third Se site, Se(3) is bonded to three equivalent Hg(1) and three equivalent Hg(2) atoms to form SeHg6 octahedra that share corners with three equivalent Se(1)Cd3Hg3 octahedra, corners with three equivalent Se(2)Hg6 octahedra, edges with three equivalent Se(1)Cd3Hg3 octahedra, edges with three equivalent Se(2)Hg6 octahedra, and edges with six equivalent Se(3)Hg6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°.
Hg4CdSe5 is Caswellsilverite-like structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded to three equivalent Se(1) and three equivalent Se(3) atoms to form HgSe6 octahedra that share corners with three equivalent Hg(2)Se6 octahedra, corners with three equivalent Cd(1)Se6 octahedra, edges with three equivalent Hg(2)Se6 octahedra, edges with three equivalent Cd(1)Se6 octahedra, and edges with six equivalent Hg(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. All Hg(1)-Se(1) bond lengths are 2.93 Å. All Hg(1)-Se(3) bond lengths are 2.90 Å. In the second Hg site, Hg(2) is bonded to three equivalent Se(2) and three equivalent Se(3) atoms to form a mixture of corner and edge-sharing HgSe6 octahedra. The corner-sharing octahedra are not tilted. All Hg(2)-Se(2) bond lengths are 2.90 Å. All Hg(2)-Se(3) bond lengths are 2.91 Å. Cd(1) is bonded to six equivalent Se(1) atoms to form CdSe6 octahedra that share corners with six equivalent Hg(1)Se6 octahedra, edges with six equivalent Hg(1)Se6 octahedra, and edges with six equivalent Cd(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 1°. All Cd(1)-Se(1) bond lengths are 2.88 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Hg(1) and three equivalent Cd(1) atoms to form SeCd3Hg3 octahedra that share corners with three equivalent Se(1)Cd3Hg3 octahedra, corners with three equivalent Se(3)Hg6 octahedra, edges with three equivalent Se(3)Hg6 octahedra, and edges with nine equivalent Se(1)Cd3Hg3 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the second Se site, Se(2) is bonded to six equivalent Hg(2) atoms to form a mixture of corner and edge-sharing SeHg6 octahedra. The corner-sharing octahedra are not tilted. In the third Se site, Se(3) is bonded to three equivalent Hg(1) and three equivalent Hg(2) atoms to form SeHg6 octahedra that share corners with three equivalent Se(1)Cd3Hg3 octahedra, corners with three equivalent Se(2)Hg6 octahedra, edges with three equivalent Se(1)Cd3Hg3 octahedra, edges with three equivalent Se(2)Hg6 octahedra, and edges with six equivalent Se(3)Hg6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°.