Ce5AgSe8 crystallizes in the tetragonal I-4 space group. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. In the second Ce site, Ce(2) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. Ag(1) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one Ce(2), four equivalent Ce(1), and one Ag(1) atom to form a mixture of distorted corner, face, and edge-sharing SeCe5Ag octahedra. The corner-sharing octahedral tilt angles range from 16-47°. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Ce(2), four equivalent Ce(1), and one Ag(1) atom.
Ce5AgSe8 crystallizes in the tetragonal I-4 space group. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. There are a spread of Ce(1)-Se(1) bond distances ranging from 2.96-3.27 Å. There are a spread of Ce(1)-Se(2) bond distances ranging from 2.97-3.18 Å. In the second Ce site, Ce(2) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. All Ce(2)-Se(1) bond lengths are 3.16 Å. All Ce(2)-Se(2) bond lengths are 2.96 Å. Ag(1) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. All Ag(1)-Se(1) bond lengths are 2.92 Å. All Ag(1)-Se(2) bond lengths are 3.33 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one Ce(2), four equivalent Ce(1), and one Ag(1) atom to form a mixture of distorted corner, face, and edge-sharing SeCe5Ag octahedra. The corner-sharing octahedral tilt angles range from 16-47°. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Ce(2), four equivalent Ce(1), and one Ag(1) atom.