Pr3CBr5 crystallizes in the triclinic P-1 space group. There are three inequivalent Pr sites. In the first Pr site, Pr(1) is bonded to two equivalent C(1), one Br(2), one Br(3), one Br(4), and two equivalent Br(1) atoms to form distorted PrC2Br5 pentagonal bipyramids that share  a cornercorner with one Pr(3)CBr5 octahedra, corners with two equivalent Pr(2)C2Br5 pentagonal bipyramids, edges with three equivalent Pr(3)CBr5 octahedra, edges with two equivalent Pr(1)C2Br5 pentagonal bipyramids, and faces with two equivalent Pr(2)C2Br5 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 4°. In the second Pr site, Pr(2) is bonded to two equivalent C(1), one Br(2), one Br(3), one Br(5), and two equivalent Br(4) atoms to form PrC2Br5 pentagonal bipyramids that share corners with two equivalent Pr(1)C2Br5 pentagonal bipyramids, edges with three equivalent Pr(3)CBr5 octahedra, edges with two equivalent Pr(2)C2Br5 pentagonal bipyramids, and faces with two equivalent Pr(1)C2Br5 pentagonal bipyramids. In the third Pr site, Pr(3) is bonded to one C(1), one Br(1), one Br(3), one Br(5), and two equivalent Br(2) atoms to form PrCBr5 octahedra that share  a cornercorner with one Pr(1)C2Br5 pentagonal bipyramid,  an edgeedge with one Pr(3)CBr5 octahedra, edges with three equivalent Pr(1)C2Br5 pentagonal bipyramids, and edges with three equivalent Pr(2)C2Br5 pentagonal bipyramids. C(1) is bonded in a 6-coordinate geometry to one Pr(3), two equivalent Pr(1), two equivalent Pr(2), and one C(1) atom. There are five inequivalent Br sites. In the first Br site, Br(1) is bonded in a T-shaped geometry to one Pr(3) and two equivalent Pr(1) atoms. In the second Br site, Br(2) is bonded in a see-saw-like geometry to one Pr(1), one Pr(2), and two equivalent Pr(3) atoms. In the third Br site, Br(3) is bonded in a 3-coordinate geometry to one Pr(1), one Pr(2), and one Pr(3) atom. In the fourth Br site, Br(4) is bonded in a distorted T-shaped geometry to one Pr(1) and two equivalent Pr(2) atoms. In the fifth Br site, Br(5) is bonded in an L-shaped geometry to one Pr(2) and one Pr(3) atom.
Pr3CBr5 crystallizes in the triclinic P-1 space group. There are three inequivalent Pr sites. In the first Pr site, Pr(1) is bonded to two equivalent C(1), one Br(2), one Br(3), one Br(4), and two equivalent Br(1) atoms to form distorted PrC2Br5 pentagonal bipyramids that share  a cornercorner with one Pr(3)CBr5 octahedra, corners with two equivalent Pr(2)C2Br5 pentagonal bipyramids, edges with three equivalent Pr(3)CBr5 octahedra, edges with two equivalent Pr(1)C2Br5 pentagonal bipyramids, and faces with two equivalent Pr(2)C2Br5 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 4°. There is one shorter (2.61 Å) and one longer (2.63 Å) Pr(1)-C(1) bond length. The Pr(1)-Br(2) bond length is 3.14 Å. The Pr(1)-Br(3) bond length is 2.96 Å. The Pr(1)-Br(4) bond length is 2.95 Å. There is one shorter (3.01 Å) and one longer (3.19 Å) Pr(1)-Br(1) bond length. In the second Pr site, Pr(2) is bonded to two equivalent C(1), one Br(2), one Br(3), one Br(5), and two equivalent Br(4) atoms to form PrC2Br5 pentagonal bipyramids that share corners with two equivalent Pr(1)C2Br5 pentagonal bipyramids, edges with three equivalent Pr(3)CBr5 octahedra, edges with two equivalent Pr(2)C2Br5 pentagonal bipyramids, and faces with two equivalent Pr(1)C2Br5 pentagonal bipyramids. There is one shorter (2.63 Å) and one longer (2.65 Å) Pr(2)-C(1) bond length. The Pr(2)-Br(2) bond length is 3.19 Å. The Pr(2)-Br(3) bond length is 2.97 Å. The Pr(2)-Br(5) bond length is 2.95 Å. There is one shorter (2.97 Å) and one longer (3.18 Å) Pr(2)-Br(4) bond length. In the third Pr site, Pr(3) is bonded to one C(1), one Br(1), one Br(3), one Br(5), and two equivalent Br(2) atoms to form PrCBr5 octahedra that share  a cornercorner with one Pr(1)C2Br5 pentagonal bipyramid,  an edgeedge with one Pr(3)CBr5 octahedra, edges with three equivalent Pr(1)C2Br5 pentagonal bipyramids, and edges with three equivalent Pr(2)C2Br5 pentagonal bipyramids. The Pr(3)-C(1) bond length is 2.32 Å. The Pr(3)-Br(1) bond length is 2.96 Å. The Pr(3)-Br(3) bond length is 3.17 Å. The Pr(3)-Br(5) bond length is 2.89 Å. There is one shorter (3.10 Å) and one longer (3.14 Å) Pr(3)-Br(2) bond length. C(1) is bonded in a 6-coordinate geometry to one Pr(3), two equivalent Pr(1), two equivalent Pr(2), and one C(1) atom. The C(1)-C(1) bond length is 1.40 Å. There are five inequivalent Br sites. In the first Br site, Br(1) is bonded in a T-shaped geometry to one Pr(3) and two equivalent Pr(1) atoms. In the second Br site, Br(2) is bonded in a see-saw-like geometry to one Pr(1), one Pr(2), and two equivalent Pr(3) atoms. In the third Br site, Br(3) is bonded in a 3-coordinate geometry to one Pr(1), one Pr(2), and one Pr(3) atom. In the fourth Br site, Br(4) is bonded in a distorted T-shaped geometry to one Pr(1) and two equivalent Pr(2) atoms. In the fifth Br site, Br(5) is bonded in an L-shaped geometry to one Pr(2) and one Pr(3) atom.