CsPr3CI6 crystallizes in the triclinic P-1 space group. Cs(1) is bonded in a 11-coordinate geometry to one I(1), two equivalent I(2), two equivalent I(3), two equivalent I(4), two equivalent I(5), and two equivalent I(6) atoms. There are three inequivalent Pr sites. In the first Pr site, Pr(1) is bonded to two equivalent C(1), one I(1), one I(2), one I(6), and two equivalent I(3) atoms to form distorted PrC2I5 pentagonal bipyramids that share  a cornercorner with one Pr(2)CI5 octahedra, corners with two equivalent Pr(3)C2I5 pentagonal bipyramids, edges with two equivalent Pr(2)CI5 octahedra, edges with two equivalent Pr(1)C2I5 pentagonal bipyramids, and faces with two equivalent Pr(3)C2I5 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 11°. In the second Pr site, Pr(2) is bonded to one C(1), one I(4), one I(5), one I(6), and two equivalent I(1) atoms to form distorted PrCI5 octahedra that share  a cornercorner with one Pr(1)C2I5 pentagonal bipyramid,  an edgeedge with one Pr(2)CI5 octahedra, edges with two equivalent Pr(1)C2I5 pentagonal bipyramids, and edges with two equivalent Pr(3)C2I5 pentagonal bipyramids. In the third Pr site, Pr(3) is bonded to two equivalent C(1), one I(3), one I(4), one I(5), and two equivalent I(2) atoms to form distorted PrC2I5 pentagonal bipyramids that share corners with two equivalent Pr(1)C2I5 pentagonal bipyramids, edges with two equivalent Pr(2)CI5 octahedra, edges with two equivalent Pr(3)C2I5 pentagonal bipyramids, and faces with two equivalent Pr(1)C2I5 pentagonal bipyramids. C(1) is bonded in a 6-coordinate geometry to one Pr(2), two equivalent Pr(1), two equivalent Pr(3), and one C(1) atom. There are six inequivalent I sites. In the first I site, I(1) is bonded in a distorted see-saw-like geometry to one Cs(1), one Pr(1), and two equivalent Pr(2) atoms. In the second I site, I(2) is bonded in a 3-coordinate geometry to two equivalent Cs(1), one Pr(1), and two equivalent Pr(3) atoms. In the third I site, I(3) is bonded in a 5-coordinate geometry to two equivalent Cs(1), one Pr(3), and two equivalent Pr(1) atoms. In the fourth I site, I(4) is bonded in a 4-coordinate geometry to two equivalent Cs(1), one Pr(2), and one Pr(3) atom. In the fifth I site, I(5) is bonded in a 4-coordinate geometry to two equivalent Cs(1), one Pr(2), and one Pr(3) atom. In the sixth I site, I(6) is bonded in a 2-coordinate geometry to two equivalent Cs(1), one Pr(1), and one Pr(2) atom.
CsPr3CI6 crystallizes in the triclinic P-1 space group. Cs(1) is bonded in a 11-coordinate geometry to one I(1), two equivalent I(2), two equivalent I(3), two equivalent I(4), two equivalent I(5), and two equivalent I(6) atoms. The Cs(1)-I(1) bond length is 4.10 Å. There is one shorter (4.23 Å) and one longer (4.51 Å) Cs(1)-I(2) bond length. There is one shorter (4.30 Å) and one longer (4.35 Å) Cs(1)-I(3) bond length. There is one shorter (4.28 Å) and one longer (4.31 Å) Cs(1)-I(4) bond length. There is one shorter (4.00 Å) and one longer (4.23 Å) Cs(1)-I(5) bond length. There is one shorter (4.24 Å) and one longer (4.49 Å) Cs(1)-I(6) bond length. There are three inequivalent Pr sites. In the first Pr site, Pr(1) is bonded to two equivalent C(1), one I(1), one I(2), one I(6), and two equivalent I(3) atoms to form distorted PrC2I5 pentagonal bipyramids that share  a cornercorner with one Pr(2)CI5 octahedra, corners with two equivalent Pr(3)C2I5 pentagonal bipyramids, edges with two equivalent Pr(2)CI5 octahedra, edges with two equivalent Pr(1)C2I5 pentagonal bipyramids, and faces with two equivalent Pr(3)C2I5 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 11°. Both Pr(1)-C(1) bond lengths are 2.65 Å. The Pr(1)-I(1) bond length is 3.29 Å. The Pr(1)-I(2) bond length is 3.18 Å. The Pr(1)-I(6) bond length is 3.23 Å. There is one shorter (3.20 Å) and one longer (3.52 Å) Pr(1)-I(3) bond length. In the second Pr site, Pr(2) is bonded to one C(1), one I(4), one I(5), one I(6), and two equivalent I(1) atoms to form distorted PrCI5 octahedra that share  a cornercorner with one Pr(1)C2I5 pentagonal bipyramid,  an edgeedge with one Pr(2)CI5 octahedra, edges with two equivalent Pr(1)C2I5 pentagonal bipyramids, and edges with two equivalent Pr(3)C2I5 pentagonal bipyramids. The Pr(2)-C(1) bond length is 2.35 Å. The Pr(2)-I(4) bond length is 3.20 Å. The Pr(2)-I(5) bond length is 3.20 Å. The Pr(2)-I(6) bond length is 3.18 Å. There is one shorter (3.24 Å) and one longer (3.47 Å) Pr(2)-I(1) bond length. In the third Pr site, Pr(3) is bonded to two equivalent C(1), one I(3), one I(4), one I(5), and two equivalent I(2) atoms to form distorted PrC2I5 pentagonal bipyramids that share corners with two equivalent Pr(1)C2I5 pentagonal bipyramids, edges with two equivalent Pr(2)CI5 octahedra, edges with two equivalent Pr(3)C2I5 pentagonal bipyramids, and faces with two equivalent Pr(1)C2I5 pentagonal bipyramids. Both Pr(3)-C(1) bond lengths are 2.66 Å. The Pr(3)-I(3) bond length is 3.21 Å. The Pr(3)-I(4) bond length is 3.25 Å. The Pr(3)-I(5) bond length is 3.25 Å. There is one shorter (3.21 Å) and one longer (3.47 Å) Pr(3)-I(2) bond length. C(1) is bonded in a 6-coordinate geometry to one Pr(2), two equivalent Pr(1), two equivalent Pr(3), and one C(1) atom. The C(1)-C(1) bond length is 1.41 Å. There are six inequivalent I sites. In the first I site, I(1) is bonded in a distorted see-saw-like geometry to one Cs(1), one Pr(1), and two equivalent Pr(2) atoms. In the second I site, I(2) is bonded in a 3-coordinate geometry to two equivalent Cs(1), one Pr(1), and two equivalent Pr(3) atoms. In the third I site, I(3) is bonded in a 5-coordinate geometry to two equivalent Cs(1), one Pr(3), and two equivalent Pr(1) atoms. In the fourth I site, I(4) is bonded in a 4-coordinate geometry to two equivalent Cs(1), one Pr(2), and one Pr(3) atom. In the fifth I site, I(5) is bonded in a 4-coordinate geometry to two equivalent Cs(1), one Pr(2), and one Pr(3) atom. In the sixth I site, I(6) is bonded in a 2-coordinate geometry to two equivalent Cs(1), one Pr(1), and one Pr(2) atom.