CeSe2 crystallizes in the triclinic P-1 space group. There are three inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 9-coordinate geometry to one Se(3), two equivalent Se(1), two equivalent Se(4), two equivalent Se(5), and two equivalent Se(6) atoms. In the second Ce site, Ce(2) is bonded in a 8-coordinate geometry to one Se(1), one Se(3), one Se(4), one Se(5), two equivalent Se(2), and two equivalent Se(6) atoms. In the third Ce site, Ce(3) is bonded in a 7-coordinate geometry to one Se(1), one Se(4), one Se(5), two equivalent Se(2), and two equivalent Se(3) atoms. There are six inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one Ce(2), one Ce(3), two equivalent Ce(1), and two equivalent Se(4) atoms. In the second Se site, Se(2) is bonded to two equivalent Ce(2) and two equivalent Ce(3) atoms to form a mixture of distorted edge and corner-sharing SeCe4 tetrahedra. In the third Se site, Se(3) is bonded in a distorted bent 150 degrees geometry to one Ce(1), one Ce(2), and two equivalent Ce(3) atoms. In the fourth Se site, Se(4) is bonded in a 6-coordinate geometry to one Ce(2), one Ce(3), two equivalent Ce(1), and two equivalent Se(1) atoms. In the fifth Se site, Se(5) is bonded to one Ce(2), one Ce(3), and two equivalent Ce(1) atoms to form distorted corner-sharing SeCe4 trigonal pyramids. In the sixth Se site, Se(6) is bonded in a 6-coordinate geometry to two equivalent Ce(1), two equivalent Ce(2), and two equivalent Se(6) atoms.
CeSe2 crystallizes in the triclinic P-1 space group. There are three inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 9-coordinate geometry to one Se(3), two equivalent Se(1), two equivalent Se(4), two equivalent Se(5), and two equivalent Se(6) atoms. The Ce(1)-Se(3) bond length is 3.59 Å. There is one shorter (3.14 Å) and one longer (3.25 Å) Ce(1)-Se(1) bond length. There is one shorter (3.15 Å) and one longer (3.16 Å) Ce(1)-Se(4) bond length. There is one shorter (3.00 Å) and one longer (3.01 Å) Ce(1)-Se(5) bond length. There is one shorter (3.14 Å) and one longer (3.16 Å) Ce(1)-Se(6) bond length. In the second Ce site, Ce(2) is bonded in a 8-coordinate geometry to one Se(1), one Se(3), one Se(4), one Se(5), two equivalent Se(2), and two equivalent Se(6) atoms. The Ce(2)-Se(1) bond length is 3.07 Å. The Ce(2)-Se(3) bond length is 3.74 Å. The Ce(2)-Se(4) bond length is 3.09 Å. The Ce(2)-Se(5) bond length is 3.02 Å. There is one shorter (2.96 Å) and one longer (2.98 Å) Ce(2)-Se(2) bond length. There is one shorter (3.09 Å) and one longer (3.13 Å) Ce(2)-Se(6) bond length. In the third Ce site, Ce(3) is bonded in a 7-coordinate geometry to one Se(1), one Se(4), one Se(5), two equivalent Se(2), and two equivalent Se(3) atoms. The Ce(3)-Se(1) bond length is 3.09 Å. The Ce(3)-Se(4) bond length is 3.08 Å. The Ce(3)-Se(5) bond length is 2.95 Å. There is one shorter (2.95 Å) and one longer (3.41 Å) Ce(3)-Se(2) bond length. There is one shorter (2.87 Å) and one longer (2.89 Å) Ce(3)-Se(3) bond length. There are six inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one Ce(2), one Ce(3), two equivalent Ce(1), and two equivalent Se(4) atoms. There is one shorter (2.76 Å) and one longer (2.78 Å) Se(1)-Se(4) bond length. In the second Se site, Se(2) is bonded to two equivalent Ce(2) and two equivalent Ce(3) atoms to form a mixture of distorted edge and corner-sharing SeCe4 tetrahedra. In the third Se site, Se(3) is bonded in a distorted bent 150 degrees geometry to one Ce(1), one Ce(2), and two equivalent Ce(3) atoms. In the fourth Se site, Se(4) is bonded in a 6-coordinate geometry to one Ce(2), one Ce(3), two equivalent Ce(1), and two equivalent Se(1) atoms. In the fifth Se site, Se(5) is bonded to one Ce(2), one Ce(3), and two equivalent Ce(1) atoms to form distorted corner-sharing SeCe4 trigonal pyramids. In the sixth Se site, Se(6) is bonded in a 6-coordinate geometry to two equivalent Ce(1), two equivalent Ce(2), and two equivalent Se(6) atoms. There is one shorter (2.71 Å) and one longer (2.82 Å) Se(6)-Se(6) bond length.