Pr21Fe8C12Bi7 crystallizes in the cubic Fm-3m space group. There are three inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 6-coordinate geometry to three equivalent C(1) and three equivalent Bi(1) atoms. In the second Pr site, Pr(2) is bonded in a distorted L-shaped geometry to two equivalent C(1), one Bi(2), and two equivalent Bi(1) atoms. In the third Pr site, Pr(3) is bonded in an octahedral geometry to six equivalent Bi(1) atoms. Fe(1) is bonded in a trigonal planar geometry to three equivalent C(1) atoms. C(1) is bonded to two equivalent Pr(1), two equivalent Pr(2), and two equivalent Fe(1) atoms to form distorted CPr4Fe2 octahedra that share corners with two equivalent Bi(2)Pr12 cuboctahedra and edges with five equivalent C(1)Pr4Fe2 octahedra. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 9-coordinate geometry to one Pr(3), four equivalent Pr(1), and four equivalent Pr(2) atoms. In the second Bi site, Bi(2) is bonded to twelve equivalent Pr(2) atoms to form BiPr12 cuboctahedra that share corners with twenty-four equivalent C(1)Pr4Fe2 octahedra. The corner-sharing octahedral tilt angles are 44°.
Pr21Fe8C12Bi7 crystallizes in the cubic Fm-3m space group. There are three inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 6-coordinate geometry to three equivalent C(1) and three equivalent Bi(1) atoms. All Pr(1)-C(1) bond lengths are 2.66 Å. All Pr(1)-Bi(1) bond lengths are 3.39 Å. In the second Pr site, Pr(2) is bonded in a distorted L-shaped geometry to two equivalent C(1), one Bi(2), and two equivalent Bi(1) atoms. Both Pr(2)-C(1) bond lengths are 2.55 Å. The Pr(2)-Bi(2) bond length is 3.96 Å. Both Pr(2)-Bi(1) bond lengths are 3.41 Å. In the third Pr site, Pr(3) is bonded in an octahedral geometry to six equivalent Bi(1) atoms. All Pr(3)-Bi(1) bond lengths are 3.44 Å. Fe(1) is bonded in a trigonal planar geometry to three equivalent C(1) atoms. All Fe(1)-C(1) bond lengths are 1.90 Å. C(1) is bonded to two equivalent Pr(1), two equivalent Pr(2), and two equivalent Fe(1) atoms to form distorted CPr4Fe2 octahedra that share corners with two equivalent Bi(2)Pr12 cuboctahedra and edges with five equivalent C(1)Pr4Fe2 octahedra. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 9-coordinate geometry to one Pr(3), four equivalent Pr(1), and four equivalent Pr(2) atoms. In the second Bi site, Bi(2) is bonded to twelve equivalent Pr(2) atoms to form BiPr12 cuboctahedra that share corners with twenty-four equivalent C(1)Pr4Fe2 octahedra. The corner-sharing octahedral tilt angles are 44°.