Pr3NbO7 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Pr sites. In the first Pr site, Pr(1) is bonded to one O(1), two equivalent O(2), and four equivalent O(3) atoms to form distorted PrO7 pentagonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra, corners with three equivalent Pr(1)O7 pentagonal bipyramids, edges with two equivalent Nb(1)O6 octahedra, and edges with two equivalent Pr(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 38°. In the second Pr site, Pr(2) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. Nb(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Pr(1)O7 pentagonal bipyramids, and edges with four equivalent Pr(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 31°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Pr(1) and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded to two equivalent Pr(1) and two equivalent Pr(2) atoms to form a mixture of corner and edge-sharing OPr4 tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Pr(2), two equivalent Pr(1), and one Nb(1) atom.
Pr3NbO7 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Pr sites. In the first Pr site, Pr(1) is bonded to one O(1), two equivalent O(2), and four equivalent O(3) atoms to form distorted PrO7 pentagonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra, corners with three equivalent Pr(1)O7 pentagonal bipyramids, edges with two equivalent Nb(1)O6 octahedra, and edges with two equivalent Pr(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 38°. The Pr(1)-O(1) bond length is 2.68 Å. There is one shorter (2.32 Å) and one longer (2.33 Å) Pr(1)-O(2) bond length. There are two shorter (2.47 Å) and two longer (2.48 Å) Pr(1)-O(3) bond lengths. In the second Pr site, Pr(2) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. All Pr(2)-O(2) bond lengths are 2.43 Å. All Pr(2)-O(3) bond lengths are 2.75 Å. Nb(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Pr(1)O7 pentagonal bipyramids, and edges with four equivalent Pr(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 31°. Both Nb(1)-O(1) bond lengths are 2.01 Å. All Nb(1)-O(3) bond lengths are 2.01 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Pr(1) and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded to two equivalent Pr(1) and two equivalent Pr(2) atoms to form a mixture of corner and edge-sharing OPr4 tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Pr(2), two equivalent Pr(1), and one Nb(1) atom.