Pr2O3 crystallizes in the monoclinic C2/m space group. There are three inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(4), two equivalent O(3), and two equivalent O(5) atoms. In the second Pr site, Pr(2) is bonded in a 7-coordinate geometry to one O(4), one O(5), two equivalent O(1), and three equivalent O(2) atoms. In the third Pr site, Pr(3) is bonded in a 7-coordinate geometry to two equivalent O(1), two equivalent O(3), and three equivalent O(4) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Pr(1), two equivalent Pr(2), and two equivalent Pr(3) atoms to form distorted OPr5 square pyramids that share corners with two equivalent O(3)Pr4 tetrahedra, corners with five equivalent O(2)Pr4 tetrahedra, edges with two equivalent O(5)Pr6 octahedra, edges with two equivalent O(1)Pr5 square pyramids,  an edgeedge with one O(2)Pr4 tetrahedra, and edges with two equivalent O(3)Pr4 tetrahedra. In the second O site, O(2) is bonded to one Pr(1) and three equivalent Pr(2) atoms to form OPr4 tetrahedra that share  a cornercorner with one O(5)Pr6 octahedra, corners with five equivalent O(1)Pr5 square pyramids, corners with two equivalent O(2)Pr4 tetrahedra, corners with two equivalent O(3)Pr4 tetrahedra, edges with two equivalent O(5)Pr6 octahedra,  an edgeedge with one O(1)Pr5 square pyramid, and edges with two equivalent O(2)Pr4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. In the third O site, O(3) is bonded to two equivalent Pr(1) and two equivalent Pr(3) atoms to form OPr4 tetrahedra that share corners with two equivalent O(5)Pr6 octahedra, corners with two equivalent O(1)Pr5 square pyramids, corners with two equivalent O(2)Pr4 tetrahedra, corners with two equivalent O(3)Pr4 tetrahedra,  an edgeedge with one O(5)Pr6 octahedra, edges with two equivalent O(1)Pr5 square pyramids, and  an edgeedge with one O(3)Pr4 tetrahedra. The corner-sharing octahedral tilt angles are 15°. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Pr(1), one Pr(2), and three equivalent Pr(3) atoms. In the fifth O site, O(5) is bonded to two equivalent Pr(2) and four equivalent Pr(1) atoms to form OPr6 octahedra that share corners with two equivalent O(2)Pr4 tetrahedra, corners with four equivalent O(3)Pr4 tetrahedra, edges with two equivalent O(5)Pr6 octahedra, edges with four equivalent O(1)Pr5 square pyramids, edges with two equivalent O(3)Pr4 tetrahedra, and edges with four equivalent O(2)Pr4 tetrahedra.
Pr2O3 crystallizes in the monoclinic C2/m space group. There are three inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(4), two equivalent O(3), and two equivalent O(5) atoms. The Pr(1)-O(1) bond length is 2.39 Å. The Pr(1)-O(2) bond length is 2.32 Å. The Pr(1)-O(4) bond length is 3.18 Å. Both Pr(1)-O(3) bond lengths are 2.33 Å. Both Pr(1)-O(5) bond lengths are 2.64 Å. In the second Pr site, Pr(2) is bonded in a 7-coordinate geometry to one O(4), one O(5), two equivalent O(1), and three equivalent O(2) atoms. The Pr(2)-O(4) bond length is 2.42 Å. The Pr(2)-O(5) bond length is 2.84 Å. Both Pr(2)-O(1) bond lengths are 2.55 Å. There is one shorter (2.35 Å) and two longer (2.38 Å) Pr(2)-O(2) bond lengths. In the third Pr site, Pr(3) is bonded in a 7-coordinate geometry to two equivalent O(1), two equivalent O(3), and three equivalent O(4) atoms. Both Pr(3)-O(1) bond lengths are 2.61 Å. There is one shorter (2.37 Å) and one longer (2.48 Å) Pr(3)-O(3) bond length. There are two shorter (2.37 Å) and one longer (2.76 Å) Pr(3)-O(4) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Pr(1), two equivalent Pr(2), and two equivalent Pr(3) atoms to form distorted OPr5 square pyramids that share corners with two equivalent O(3)Pr4 tetrahedra, corners with five equivalent O(2)Pr4 tetrahedra, edges with two equivalent O(5)Pr6 octahedra, edges with two equivalent O(1)Pr5 square pyramids,  an edgeedge with one O(2)Pr4 tetrahedra, and edges with two equivalent O(3)Pr4 tetrahedra. In the second O site, O(2) is bonded to one Pr(1) and three equivalent Pr(2) atoms to form OPr4 tetrahedra that share  a cornercorner with one O(5)Pr6 octahedra, corners with five equivalent O(1)Pr5 square pyramids, corners with two equivalent O(2)Pr4 tetrahedra, corners with two equivalent O(3)Pr4 tetrahedra, edges with two equivalent O(5)Pr6 octahedra,  an edgeedge with one O(1)Pr5 square pyramid, and edges with two equivalent O(2)Pr4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. In the third O site, O(3) is bonded to two equivalent Pr(1) and two equivalent Pr(3) atoms to form OPr4 tetrahedra that share corners with two equivalent O(5)Pr6 octahedra, corners with two equivalent O(1)Pr5 square pyramids, corners with two equivalent O(2)Pr4 tetrahedra, corners with two equivalent O(3)Pr4 tetrahedra,  an edgeedge with one O(5)Pr6 octahedra, edges with two equivalent O(1)Pr5 square pyramids, and  an edgeedge with one O(3)Pr4 tetrahedra. The corner-sharing octahedral tilt angles are 15°. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Pr(1), one Pr(2), and three equivalent Pr(3) atoms. In the fifth O site, O(5) is bonded to two equivalent Pr(2) and four equivalent Pr(1) atoms to form OPr6 octahedra that share corners with two equivalent O(2)Pr4 tetrahedra, corners with four equivalent O(3)Pr4 tetrahedra, edges with two equivalent O(5)Pr6 octahedra, edges with four equivalent O(1)Pr5 square pyramids, edges with two equivalent O(3)Pr4 tetrahedra, and edges with four equivalent O(2)Pr4 tetrahedra.