KCuCe2Se6 crystallizes in the orthorhombic Fddd space group. K(1) is bonded in a distorted body-centered cubic geometry to four equivalent Se(2) and four equivalent Se(3) atoms. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 8-coordinate geometry to two equivalent Se(2), two equivalent Se(3), and four equivalent Se(1) atoms. In the second Ce site, Ce(2) is bonded in a 8-coordinate geometry to two equivalent Se(2), two equivalent Se(3), and four equivalent Se(1) atoms. Cu(1) is bonded in a tetrahedral geometry to two equivalent Se(1) and two equivalent Se(3) atoms. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to two equivalent Ce(1), two equivalent Ce(2), and one Cu(1) atom. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to two equivalent K(1), one Ce(1), one Ce(2), one Se(2), and one Se(3) atom. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to two equivalent K(1), one Ce(1), one Ce(2), one Cu(1), and one Se(2) atom.
KCuCe2Se6 crystallizes in the orthorhombic Fddd space group. K(1) is bonded in a distorted body-centered cubic geometry to four equivalent Se(2) and four equivalent Se(3) atoms. All K(1)-Se(2) bond lengths are 3.42 Å. There are two shorter (3.46 Å) and two longer (3.47 Å) K(1)-Se(3) bond lengths. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 8-coordinate geometry to two equivalent Se(2), two equivalent Se(3), and four equivalent Se(1) atoms. Both Ce(1)-Se(2) bond lengths are 3.01 Å. Both Ce(1)-Se(3) bond lengths are 2.94 Å. There are two shorter (2.97 Å) and two longer (3.10 Å) Ce(1)-Se(1) bond lengths. In the second Ce site, Ce(2) is bonded in a 8-coordinate geometry to two equivalent Se(2), two equivalent Se(3), and four equivalent Se(1) atoms. Both Ce(2)-Se(2) bond lengths are 3.01 Å. Both Ce(2)-Se(3) bond lengths are 2.94 Å. There are two shorter (2.97 Å) and two longer (3.15 Å) Ce(2)-Se(1) bond lengths. Cu(1) is bonded in a tetrahedral geometry to two equivalent Se(1) and two equivalent Se(3) atoms. Both Cu(1)-Se(1) bond lengths are 2.39 Å. Both Cu(1)-Se(3) bond lengths are 2.39 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to two equivalent Ce(1), two equivalent Ce(2), and one Cu(1) atom. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to two equivalent K(1), one Ce(1), one Ce(2), one Se(2), and one Se(3) atom. The Se(2)-Se(2) bond length is 2.57 Å. The Se(2)-Se(3) bond length is 2.81 Å. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to two equivalent K(1), one Ce(1), one Ce(2), one Cu(1), and one Se(2) atom.