CsNd5Se8 crystallizes in the tetragonal I-4 space group. Cs(1) is bonded in a distorted hexagonal bipyramidal geometry to four equivalent Se(1) and four equivalent Se(2) atoms. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. In the second Nd site, Nd(2) 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 Cs(1), one Nd(2), and four equivalent Nd(1) atoms to form a mixture of distorted corner, face, and edge-sharing SeCsNd5 octahedra. The corner-sharing octahedral tilt angles range from 14-55°. In the second Se site, Se(2) is bonded to one Cs(1), one Nd(2), and four equivalent Nd(1) atoms to form a mixture of distorted corner, face, and edge-sharing SeCsNd5 octahedra. The corner-sharing octahedral tilt angles range from 14-55°.
CsNd5Se8 crystallizes in the tetragonal I-4 space group. Cs(1) is bonded in a distorted hexagonal bipyramidal geometry to four equivalent Se(1) and four equivalent Se(2) atoms. All Cs(1)-Se(1) bond lengths are 3.29 Å. All Cs(1)-Se(2) bond lengths are 3.40 Å. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. There are a spread of Nd(1)-Se(1) bond distances ranging from 3.02-3.22 Å. There are a spread of Nd(1)-Se(2) bond distances ranging from 2.96-3.41 Å. In the second Nd site, Nd(2) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. All Nd(2)-Se(1) bond lengths are 3.21 Å. All Nd(2)-Se(2) bond lengths are 3.02 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one Cs(1), one Nd(2), and four equivalent Nd(1) atoms to form a mixture of distorted corner, face, and edge-sharing SeCsNd5 octahedra. The corner-sharing octahedral tilt angles range from 14-55°. In the second Se site, Se(2) is bonded to one Cs(1), one Nd(2), and four equivalent Nd(1) atoms to form a mixture of distorted corner, face, and edge-sharing SeCsNd5 octahedra. The corner-sharing octahedral tilt angles range from 14-55°.