Cs2Ce10Os2I17 crystallizes in the monoclinic C2/m space group. Cs(1) is bonded to two equivalent I(1), two equivalent I(3), two equivalent I(4), two equivalent I(5), and four equivalent I(2) atoms to form CsI12 cuboctahedra that share corners with two equivalent Ce(1)OsI5 octahedra, corners with two equivalent Ce(2)OsI5 octahedra, corners with four equivalent Ce(4)Os2I4 octahedra, corners with six equivalent Ce(3)OsI5 octahedra, edges with two equivalent Cs(1)I12 cuboctahedra,  a faceface with one Cs(1)I12 cuboctahedra, faces with two equivalent Ce(1)OsI5 octahedra, faces with two equivalent Ce(2)OsI5 octahedra, and faces with two equivalent Ce(3)OsI5 octahedra. The corner-sharing octahedral tilt angles range from 35-48°. There are four inequivalent Ce sites. In the first Ce site, Ce(1) is bonded to one Os(1), one I(4), two equivalent I(1), and two equivalent I(5) atoms to form distorted CeOsI5 octahedra that share corners with two equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Ce(4)Os2I4 octahedra, corners with two equivalent Ce(2)OsI5 octahedra, corners with two equivalent Ce(3)OsI5 octahedra,  an edgeedge with one Ce(4)Os2I4 octahedra,  an edgeedge with one Ce(1)OsI5 octahedra,  an edgeedge with one Ce(2)OsI5 octahedra, edges with two equivalent Ce(3)OsI5 octahedra, and faces with two equivalent Cs(1)I12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-10°. In the second Ce site, Ce(2) is bonded to one Os(1), one I(4), one I(5), one I(6), and two equivalent I(2) atoms to form distorted CeOsI5 octahedra that share corners with two equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Ce(4)Os2I4 octahedra,  a cornercorner with one Ce(2)OsI5 octahedra, corners with two equivalent Ce(1)OsI5 octahedra,  an edgeedge with one Ce(1)OsI5 octahedra, edges with two equivalent Ce(4)Os2I4 octahedra, edges with two equivalent Ce(3)OsI5 octahedra, and faces with two equivalent Cs(1)I12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-10°. In the third Ce site, Ce(3) is bonded to one Os(1), one I(2), two equivalent I(1), and two equivalent I(3) atoms to form distorted CeOsI5 octahedra that share corners with three equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Ce(1)OsI5 octahedra,  a cornercorner with one Ce(3)OsI5 octahedra,  an edgeedge with one Ce(1)OsI5 octahedra,  an edgeedge with one Ce(2)OsI5 octahedra, edges with two equivalent Ce(4)Os2I4 octahedra, edges with two equivalent Ce(3)OsI5 octahedra, and  a faceface with one Cs(1)I12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-9°. In the fourth Ce site, Ce(4) is bonded to two equivalent Os(1), one I(4), one I(6), and two equivalent I(3) atoms to form CeOs2I4 octahedra that share corners with four equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Ce(4)Os2I4 octahedra,  a cornercorner with one Ce(1)OsI5 octahedra,  a cornercorner with one Ce(2)OsI5 octahedra,  an edgeedge with one Ce(4)Os2I4 octahedra,  an edgeedge with one Ce(1)OsI5 octahedra, edges with two equivalent Ce(2)OsI5 octahedra, and edges with four equivalent Ce(3)OsI5 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. Os(1) is bonded to one Ce(1), one Ce(2), two equivalent Ce(3), and two equivalent Ce(4) atoms to form edge-sharing OsCe6 octahedra. There are six inequivalent I sites. In the first I site, I(4) is bonded in a 3-coordinate geometry to two equivalent Cs(1), one Ce(1), one Ce(2), and one Ce(4) atom. In the second I site, I(5) is bonded in a 3-coordinate geometry to two equivalent Cs(1), one Ce(2), and two equivalent Ce(1) atoms. In the third I site, I(6) is bonded in a distorted square co-planar geometry to two equivalent Ce(2) and two equivalent Ce(4) atoms. In the fourth I site, I(1) is bonded in a distorted rectangular see-saw-like geometry to one Cs(1), one Ce(1), and two equivalent Ce(3) atoms. In the fifth I site, I(2) is bonded in a 4-coordinate geometry to two equivalent Cs(1), one Ce(2), and one Ce(3) atom. In the sixth I site, I(3) is bonded in a 4-coordinate geometry to one Cs(1), one Ce(4), and two equivalent Ce(3) atoms.
Cs2Ce10Os2I17 crystallizes in the monoclinic C2/m space group. Cs(1) is bonded to two equivalent I(1), two equivalent I(3), two equivalent I(4), two equivalent I(5), and four equivalent I(2) atoms to form CsI12 cuboctahedra that share corners with two equivalent Ce(1)OsI5 octahedra, corners with two equivalent Ce(2)OsI5 octahedra, corners with four equivalent Ce(4)Os2I4 octahedra, corners with six equivalent Ce(3)OsI5 octahedra, edges with two equivalent Cs(1)I12 cuboctahedra,  a faceface with one Cs(1)I12 cuboctahedra, faces with two equivalent Ce(1)OsI5 octahedra, faces with two equivalent Ce(2)OsI5 octahedra, and faces with two equivalent Ce(3)OsI5 octahedra. The corner-sharing octahedral tilt angles range from 35-48°. Both Cs(1)-I(1) bond lengths are 4.41 Å. Both Cs(1)-I(3) bond lengths are 4.15 Å. Both Cs(1)-I(4) bond lengths are 4.48 Å. Both Cs(1)-I(5) bond lengths are 4.45 Å. There are two shorter (4.26 Å) and two longer (4.33 Å) Cs(1)-I(2) bond lengths. There are four inequivalent Ce sites. In the first Ce site, Ce(1) is bonded to one Os(1), one I(4), two equivalent I(1), and two equivalent I(5) atoms to form distorted CeOsI5 octahedra that share corners with two equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Ce(4)Os2I4 octahedra, corners with two equivalent Ce(2)OsI5 octahedra, corners with two equivalent Ce(3)OsI5 octahedra,  an edgeedge with one Ce(4)Os2I4 octahedra,  an edgeedge with one Ce(1)OsI5 octahedra,  an edgeedge with one Ce(2)OsI5 octahedra, edges with two equivalent Ce(3)OsI5 octahedra, and faces with two equivalent Cs(1)I12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-10°. The Ce(1)-Os(1) bond length is 2.78 Å. The Ce(1)-I(4) bond length is 3.22 Å. Both Ce(1)-I(1) bond lengths are 3.22 Å. There is one shorter (3.24 Å) and one longer (3.41 Å) Ce(1)-I(5) bond length. In the second Ce site, Ce(2) is bonded to one Os(1), one I(4), one I(5), one I(6), and two equivalent I(2) atoms to form distorted CeOsI5 octahedra that share corners with two equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Ce(4)Os2I4 octahedra,  a cornercorner with one Ce(2)OsI5 octahedra, corners with two equivalent Ce(1)OsI5 octahedra,  an edgeedge with one Ce(1)OsI5 octahedra, edges with two equivalent Ce(4)Os2I4 octahedra, edges with two equivalent Ce(3)OsI5 octahedra, and faces with two equivalent Cs(1)I12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-10°. The Ce(2)-Os(1) bond length is 2.72 Å. The Ce(2)-I(4) bond length is 3.40 Å. The Ce(2)-I(5) bond length is 3.23 Å. The Ce(2)-I(6) bond length is 3.20 Å. Both Ce(2)-I(2) bond lengths are 3.20 Å. In the third Ce site, Ce(3) is bonded to one Os(1), one I(2), two equivalent I(1), and two equivalent I(3) atoms to form distorted CeOsI5 octahedra that share corners with three equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Ce(1)OsI5 octahedra,  a cornercorner with one Ce(3)OsI5 octahedra,  an edgeedge with one Ce(1)OsI5 octahedra,  an edgeedge with one Ce(2)OsI5 octahedra, edges with two equivalent Ce(4)Os2I4 octahedra, edges with two equivalent Ce(3)OsI5 octahedra, and  a faceface with one Cs(1)I12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-9°. The Ce(3)-Os(1) bond length is 2.79 Å. The Ce(3)-I(2) bond length is 3.18 Å. There is one shorter (3.23 Å) and one longer (3.42 Å) Ce(3)-I(1) bond length. Both Ce(3)-I(3) bond lengths are 3.23 Å. In the fourth Ce site, Ce(4) is bonded to two equivalent Os(1), one I(4), one I(6), and two equivalent I(3) atoms to form CeOs2I4 octahedra that share corners with four equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Ce(4)Os2I4 octahedra,  a cornercorner with one Ce(1)OsI5 octahedra,  a cornercorner with one Ce(2)OsI5 octahedra,  an edgeedge with one Ce(4)Os2I4 octahedra,  an edgeedge with one Ce(1)OsI5 octahedra, edges with two equivalent Ce(2)OsI5 octahedra, and edges with four equivalent Ce(3)OsI5 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. There is one shorter (2.81 Å) and one longer (2.90 Å) Ce(4)-Os(1) bond length. The Ce(4)-I(4) bond length is 3.46 Å. The Ce(4)-I(6) bond length is 3.39 Å. Both Ce(4)-I(3) bond lengths are 3.29 Å. Os(1) is bonded to one Ce(1), one Ce(2), two equivalent Ce(3), and two equivalent Ce(4) atoms to form edge-sharing OsCe6 octahedra. There are six inequivalent I sites. In the first I site, I(4) is bonded in a 3-coordinate geometry to two equivalent Cs(1), one Ce(1), one Ce(2), and one Ce(4) atom. In the second I site, I(5) is bonded in a 3-coordinate geometry to two equivalent Cs(1), one Ce(2), and two equivalent Ce(1) atoms. In the third I site, I(6) is bonded in a distorted square co-planar geometry to two equivalent Ce(2) and two equivalent Ce(4) atoms. In the fourth I site, I(1) is bonded in a distorted rectangular see-saw-like geometry to one Cs(1), one Ce(1), and two equivalent Ce(3) atoms. In the fifth I site, I(2) is bonded in a 4-coordinate geometry to two equivalent Cs(1), one Ce(2), and one Ce(3) atom. In the sixth I site, I(3) is bonded in a 4-coordinate geometry to one Cs(1), one Ce(4), and two equivalent Ce(3) atoms.