Cs2Pr10Os2I17 crystallizes in the monoclinic C2/m space group. Cs(1) is bonded to two equivalent I(2), two equivalent I(3), two equivalent I(4), two equivalent I(5), and four equivalent I(1) atoms to form distorted CsI12 cuboctahedra that share corners with two equivalent Pr(2)OsI5 octahedra, corners with two equivalent Pr(4)OsI5 octahedra, corners with four equivalent Pr(3)Os2I4 octahedra, corners with six equivalent Pr(1)OsI5 octahedra, edges with two equivalent Cs(1)I12 cuboctahedra,  a faceface with one Cs(1)I12 cuboctahedra, faces with two equivalent Pr(1)OsI5 octahedra, faces with two equivalent Pr(2)OsI5 octahedra, and faces with two equivalent Pr(4)OsI5 octahedra. The corner-sharing octahedral tilt angles range from 35-48°. There are four inequivalent Pr sites. In the first Pr site, Pr(1) is bonded to one Os(1), one I(1), two equivalent I(2), and two equivalent I(4) atoms to form PrOsI5 octahedra that share corners with three equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Pr(1)OsI5 octahedra,  a cornercorner with one Pr(2)OsI5 octahedra,  an edgeedge with one Pr(2)OsI5 octahedra,  an edgeedge with one Pr(4)OsI5 octahedra, edges with two equivalent Pr(3)Os2I4 octahedra, edges with two equivalent Pr(1)OsI5 octahedra, and  a faceface with one Cs(1)I12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-9°. In the second Pr site, Pr(2) is bonded to one Os(1), one I(5), two equivalent I(2), and two equivalent I(3) atoms to form distorted PrOsI5 octahedra that share corners with two equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Pr(3)Os2I4 octahedra, corners with two equivalent Pr(1)OsI5 octahedra, corners with two equivalent Pr(4)OsI5 octahedra,  an edgeedge with one Pr(3)Os2I4 octahedra,  an edgeedge with one Pr(2)OsI5 octahedra,  an edgeedge with one Pr(4)OsI5 octahedra, edges with two equivalent Pr(1)OsI5 octahedra, and faces with two equivalent Cs(1)I12 cuboctahedra. The corner-sharing octahedral tilt angles range from 4-10°. In the third Pr site, Pr(3) is bonded to two equivalent Os(1), one I(5), one I(6), and two equivalent I(4) atoms to form PrOs2I4 octahedra that share corners with four equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Pr(3)Os2I4 octahedra,  a cornercorner with one Pr(2)OsI5 octahedra,  a cornercorner with one Pr(4)OsI5 octahedra,  an edgeedge with one Pr(3)Os2I4 octahedra,  an edgeedge with one Pr(2)OsI5 octahedra, edges with two equivalent Pr(4)OsI5 octahedra, and edges with four equivalent Pr(1)OsI5 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the fourth Pr site, Pr(4) is bonded to one Os(1), one I(3), one I(5), one I(6), and two equivalent I(1) atoms to form distorted PrOsI5 octahedra that share corners with two equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Pr(3)Os2I4 octahedra,  a cornercorner with one Pr(4)OsI5 octahedra, corners with two equivalent Pr(2)OsI5 octahedra,  an edgeedge with one Pr(2)OsI5 octahedra, edges with two equivalent Pr(3)Os2I4 octahedra, edges with two equivalent Pr(1)OsI5 octahedra, and faces with two equivalent Cs(1)I12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-10°. Os(1) is bonded to one Pr(2), one Pr(4), two equivalent Pr(1), and two equivalent Pr(3) atoms to form edge-sharing OsPr6 octahedra. There are six inequivalent I sites. In the first I site, I(2) is bonded in a 3-coordinate geometry to one Cs(1), one Pr(2), and two equivalent Pr(1) atoms. In the second I site, I(3) is bonded in a distorted T-shaped geometry to two equivalent Cs(1), one Pr(4), and two equivalent Pr(2) atoms. In the third I site, I(4) is bonded in a 4-coordinate geometry to one Cs(1), one Pr(3), and two equivalent Pr(1) atoms. In the fourth I site, I(5) is bonded in a 3-coordinate geometry to two equivalent Cs(1), one Pr(2), one Pr(3), and one Pr(4) atom. In the fifth I site, I(6) is bonded in a distorted square co-planar geometry to two equivalent Pr(3) and two equivalent Pr(4) atoms. In the sixth I site, I(1) is bonded in a 4-coordinate geometry to two equivalent Cs(1), one Pr(1), and one Pr(4) atom.
Cs2Pr10Os2I17 crystallizes in the monoclinic C2/m space group. Cs(1) is bonded to two equivalent I(2), two equivalent I(3), two equivalent I(4), two equivalent I(5), and four equivalent I(1) atoms to form distorted CsI12 cuboctahedra that share corners with two equivalent Pr(2)OsI5 octahedra, corners with two equivalent Pr(4)OsI5 octahedra, corners with four equivalent Pr(3)Os2I4 octahedra, corners with six equivalent Pr(1)OsI5 octahedra, edges with two equivalent Cs(1)I12 cuboctahedra,  a faceface with one Cs(1)I12 cuboctahedra, faces with two equivalent Pr(1)OsI5 octahedra, faces with two equivalent Pr(2)OsI5 octahedra, and faces with two equivalent Pr(4)OsI5 octahedra. The corner-sharing octahedral tilt angles range from 35-48°. Both Cs(1)-I(2) bond lengths are 4.52 Å. Both Cs(1)-I(3) bond lengths are 4.55 Å. Both Cs(1)-I(4) bond lengths are 4.25 Å. Both Cs(1)-I(5) bond lengths are 4.56 Å. There are two shorter (4.33 Å) and two longer (4.43 Å) Cs(1)-I(1) bond lengths. There are four inequivalent Pr sites. In the first Pr site, Pr(1) is bonded to one Os(1), one I(1), two equivalent I(2), and two equivalent I(4) atoms to form PrOsI5 octahedra that share corners with three equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Pr(1)OsI5 octahedra,  a cornercorner with one Pr(2)OsI5 octahedra,  an edgeedge with one Pr(2)OsI5 octahedra,  an edgeedge with one Pr(4)OsI5 octahedra, edges with two equivalent Pr(3)Os2I4 octahedra, edges with two equivalent Pr(1)OsI5 octahedra, and  a faceface with one Cs(1)I12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-9°. The Pr(1)-Os(1) bond length is 2.87 Å. The Pr(1)-I(1) bond length is 3.20 Å. There is one shorter (3.24 Å) and one longer (3.50 Å) Pr(1)-I(2) bond length. There is one shorter (3.27 Å) and one longer (3.29 Å) Pr(1)-I(4) bond length. In the second Pr site, Pr(2) is bonded to one Os(1), one I(5), two equivalent I(2), and two equivalent I(3) atoms to form distorted PrOsI5 octahedra that share corners with two equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Pr(3)Os2I4 octahedra, corners with two equivalent Pr(1)OsI5 octahedra, corners with two equivalent Pr(4)OsI5 octahedra,  an edgeedge with one Pr(3)Os2I4 octahedra,  an edgeedge with one Pr(2)OsI5 octahedra,  an edgeedge with one Pr(4)OsI5 octahedra, edges with two equivalent Pr(1)OsI5 octahedra, and faces with two equivalent Cs(1)I12 cuboctahedra. The corner-sharing octahedral tilt angles range from 4-10°. The Pr(2)-Os(1) bond length is 2.79 Å. The Pr(2)-I(5) bond length is 3.27 Å. Both Pr(2)-I(2) bond lengths are 3.27 Å. There is one shorter (3.28 Å) and one longer (3.51 Å) Pr(2)-I(3) bond length. In the third Pr site, Pr(3) is bonded to two equivalent Os(1), one I(5), one I(6), and two equivalent I(4) atoms to form PrOs2I4 octahedra that share corners with four equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Pr(3)Os2I4 octahedra,  a cornercorner with one Pr(2)OsI5 octahedra,  a cornercorner with one Pr(4)OsI5 octahedra,  an edgeedge with one Pr(3)Os2I4 octahedra,  an edgeedge with one Pr(2)OsI5 octahedra, edges with two equivalent Pr(4)OsI5 octahedra, and edges with four equivalent Pr(1)OsI5 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. There is one shorter (2.87 Å) and one longer (2.95 Å) Pr(3)-Os(1) bond length. The Pr(3)-I(5) bond length is 3.49 Å. The Pr(3)-I(6) bond length is 3.43 Å. Both Pr(3)-I(4) bond lengths are 3.36 Å. In the fourth Pr site, Pr(4) is bonded to one Os(1), one I(3), one I(5), one I(6), and two equivalent I(1) atoms to form distorted PrOsI5 octahedra that share corners with two equivalent Cs(1)I12 cuboctahedra,  a cornercorner with one Pr(3)Os2I4 octahedra,  a cornercorner with one Pr(4)OsI5 octahedra, corners with two equivalent Pr(2)OsI5 octahedra,  an edgeedge with one Pr(2)OsI5 octahedra, edges with two equivalent Pr(3)Os2I4 octahedra, edges with two equivalent Pr(1)OsI5 octahedra, and faces with two equivalent Cs(1)I12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-10°. The Pr(4)-Os(1) bond length is 2.76 Å. The Pr(4)-I(3) bond length is 3.25 Å. The Pr(4)-I(5) bond length is 3.50 Å. The Pr(4)-I(6) bond length is 3.26 Å. Both Pr(4)-I(1) bond lengths are 3.23 Å. Os(1) is bonded to one Pr(2), one Pr(4), two equivalent Pr(1), and two equivalent Pr(3) atoms to form edge-sharing OsPr6 octahedra. There are six inequivalent I sites. In the first I site, I(2) is bonded in a 3-coordinate geometry to one Cs(1), one Pr(2), and two equivalent Pr(1) atoms. In the second I site, I(3) is bonded in a distorted T-shaped geometry to two equivalent Cs(1), one Pr(4), and two equivalent Pr(2) atoms. In the third I site, I(4) is bonded in a 4-coordinate geometry to one Cs(1), one Pr(3), and two equivalent Pr(1) atoms. In the fourth I site, I(5) is bonded in a 3-coordinate geometry to two equivalent Cs(1), one Pr(2), one Pr(3), and one Pr(4) atom. In the fifth I site, I(6) is bonded in a distorted square co-planar geometry to two equivalent Pr(3) and two equivalent Pr(4) atoms. In the sixth I site, I(1) is bonded in a 4-coordinate geometry to two equivalent Cs(1), one Pr(1), and one Pr(4) atom.