CeSe2 crystallizes in the monoclinic Pc space group. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 6-coordinate geometry to one Se(1), one Se(2), two equivalent Se(3), and two equivalent Se(4) atoms. In the second Ce site, Ce(2) is bonded to one Se(2), one Se(4), two equivalent Se(1), and two equivalent Se(3) atoms to form distorted edge-sharing CeSe6 pentagonal pyramids. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted trigonal non-coplanar geometry to one Ce(1) and two equivalent Ce(2) atoms. In the second Se site, Se(2) is bonded in a linear geometry to one Ce(1) and one Ce(2) atom. In the third Se site, Se(3) is bonded in a square co-planar geometry to two equivalent Ce(1) and two equivalent Ce(2) atoms. In the fourth Se site, Se(4) is bonded in a distorted trigonal non-coplanar geometry to one Ce(2) and two equivalent Ce(1) atoms.
CeSe2 crystallizes in the monoclinic Pc space group. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 6-coordinate geometry to one Se(1), one Se(2), two equivalent Se(3), and two equivalent Se(4) atoms. The Ce(1)-Se(1) bond length is 2.86 Å. The Ce(1)-Se(2) bond length is 2.75 Å. There is one shorter (2.99 Å) and one longer (3.05 Å) Ce(1)-Se(3) bond length. There is one shorter (2.83 Å) and one longer (2.85 Å) Ce(1)-Se(4) bond length. In the second Ce site, Ce(2) is bonded to one Se(2), one Se(4), two equivalent Se(1), and two equivalent Se(3) atoms to form distorted edge-sharing CeSe6 pentagonal pyramids. The Ce(2)-Se(2) bond length is 2.75 Å. The Ce(2)-Se(4) bond length is 2.87 Å. Both Ce(2)-Se(1) bond lengths are 2.86 Å. There is one shorter (2.97 Å) and one longer (3.05 Å) Ce(2)-Se(3) bond length. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted trigonal non-coplanar geometry to one Ce(1) and two equivalent Ce(2) atoms. In the second Se site, Se(2) is bonded in a linear geometry to one Ce(1) and one Ce(2) atom. In the third Se site, Se(3) is bonded in a square co-planar geometry to two equivalent Ce(1) and two equivalent Ce(2) atoms. In the fourth Se site, Se(4) is bonded in a distorted trigonal non-coplanar geometry to one Ce(2) and two equivalent Ce(1) atoms.