La21Mn8C12Bi7 crystallizes in the cubic Fm-3m space group. There are three inequivalent La sites. In the first La site, La(1) is bonded in a distorted L-shaped geometry to two equivalent C(1), one Bi(2), and two equivalent Bi(1) atoms. In the second La site, La(2) is bonded to three equivalent C(1) and three equivalent Bi(1) atoms to form distorted LaBi3C3 octahedra that share corners with six equivalent La(2)Bi3C3 octahedra, edges with three equivalent La(2)Bi3C3 octahedra, and  a faceface with one La(3)Bi6 octahedra. The corner-sharing octahedral tilt angles range from 21-41°. In the third La site, La(3) is bonded to six equivalent Bi(1) atoms to form face-sharing LaBi6 octahedra. Mn(1) is bonded in a trigonal planar geometry to three equivalent C(1) atoms. C(1) is bonded to two equivalent La(1), two equivalent La(2), and two equivalent Mn(1) atoms to form distorted CLa4Mn2 octahedra that share corners with two equivalent Bi(2)La12 cuboctahedra and edges with five equivalent C(1)La4Mn2 octahedra. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 9-coordinate geometry to one La(3), four equivalent La(1), and four equivalent La(2) atoms. In the second Bi site, Bi(2) is bonded to twelve equivalent La(1) atoms to form BiLa12 cuboctahedra that share corners with twenty-four equivalent C(1)La4Mn2 octahedra. The corner-sharing octahedral tilt angles are 44°.
La21Mn8C12Bi7 crystallizes in the cubic Fm-3m space group. There are three inequivalent La sites. In the first La site, La(1) is bonded in a distorted L-shaped geometry to two equivalent C(1), one Bi(2), and two equivalent Bi(1) atoms. Both La(1)-C(1) bond lengths are 2.56 Å. The La(1)-Bi(2) bond length is 4.02 Å. Both La(1)-Bi(1) bond lengths are 3.46 Å. In the second La site, La(2) is bonded to three equivalent C(1) and three equivalent Bi(1) atoms to form distorted LaBi3C3 octahedra that share corners with six equivalent La(2)Bi3C3 octahedra, edges with three equivalent La(2)Bi3C3 octahedra, and  a faceface with one La(3)Bi6 octahedra. The corner-sharing octahedral tilt angles range from 21-41°. All La(2)-C(1) bond lengths are 2.70 Å. All La(2)-Bi(1) bond lengths are 3.42 Å. In the third La site, La(3) is bonded to six equivalent Bi(1) atoms to form face-sharing LaBi6 octahedra. All La(3)-Bi(1) bond lengths are 3.46 Å. Mn(1) is bonded in a trigonal planar geometry to three equivalent C(1) atoms. All Mn(1)-C(1) bond lengths are 1.93 Å. C(1) is bonded to two equivalent La(1), two equivalent La(2), and two equivalent Mn(1) atoms to form distorted CLa4Mn2 octahedra that share corners with two equivalent Bi(2)La12 cuboctahedra and edges with five equivalent C(1)La4Mn2 octahedra. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 9-coordinate geometry to one La(3), four equivalent La(1), and four equivalent La(2) atoms. In the second Bi site, Bi(2) is bonded to twelve equivalent La(1) atoms to form BiLa12 cuboctahedra that share corners with twenty-four equivalent C(1)La4Mn2 octahedra. The corner-sharing octahedral tilt angles are 44°.