Ce4FeSe6O crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a distorted single-bond geometry to three equivalent Se(1), four equivalent Se(2), and one O(1) atom. In the second Ce site, Ce(2) is bonded in a 1-coordinate geometry to three equivalent Se(1), six equivalent Se(2), and one O(1) atom. Fe(1) is bonded to six equivalent Se(1) atoms to form distorted face-sharing FeSe6 octahedra. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one Ce(2), three equivalent Ce(1), and two equivalent Fe(1) atoms. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to two equivalent Ce(2) and four equivalent Ce(1) atoms. O(1) is bonded in a tetrahedral geometry to one Ce(2) and three equivalent Ce(1) atoms.
Ce4FeSe6O crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a distorted single-bond geometry to three equivalent Se(1), four equivalent Se(2), and one O(1) atom. There are two shorter (2.95 Å) and one longer (3.00 Å) Ce(1)-Se(1) bond length. There are two shorter (3.02 Å) and two longer (3.24 Å) Ce(1)-Se(2) bond lengths. The Ce(1)-O(1) bond length is 2.37 Å. In the second Ce site, Ce(2) is bonded in a 1-coordinate geometry to three equivalent Se(1), six equivalent Se(2), and one O(1) atom. All Ce(2)-Se(1) bond lengths are 3.38 Å. There are three shorter (2.95 Å) and three longer (3.62 Å) Ce(2)-Se(2) bond lengths. The Ce(2)-O(1) bond length is 2.36 Å. Fe(1) is bonded to six equivalent Se(1) atoms to form distorted face-sharing FeSe6 octahedra. There are three shorter (2.70 Å) and three longer (2.83 Å) Fe(1)-Se(1) bond lengths. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one Ce(2), three equivalent Ce(1), and two equivalent Fe(1) atoms. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to two equivalent Ce(2) and four equivalent Ce(1) atoms. O(1) is bonded in a tetrahedral geometry to one Ce(2) and three equivalent Ce(1) atoms.