Sm11(Fe2C3)6 crystallizes in the cubic I-43m space group. There are three inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 8-coordinate geometry to four equivalent C(1) and four equivalent C(2) atoms. In the second Sm site, Sm(2) is bonded in a 6-coordinate geometry to six equivalent C(2) atoms. In the third Sm site, Sm(3) is bonded in a 12-coordinate geometry to twelve equivalent Fe(1) atoms. Fe(1) is bonded in a distorted trigonal non-coplanar geometry to one Sm(3), one C(1), and two equivalent C(2) atoms. There are two inequivalent C sites. In the first C site, C(1) is bonded in a 7-coordinate geometry to four equivalent Sm(1), two equivalent Fe(1), and one C(1) atom. In the second C site, C(2) is bonded to two equivalent Sm(1), two equivalent Sm(2), and two equivalent Fe(1) atoms to form a mixture of distorted corner and edge-sharing CSm4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-72°.
Sm11(Fe2C3)6 crystallizes in the cubic I-43m space group. There are three inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 8-coordinate geometry to four equivalent C(1) and four equivalent C(2) atoms. All Sm(1)-C(1) bond lengths are 2.67 Å. All Sm(1)-C(2) bond lengths are 2.62 Å. In the second Sm site, Sm(2) is bonded in a 6-coordinate geometry to six equivalent C(2) atoms. There are three shorter (2.62 Å) and three longer (2.70 Å) Sm(2)-C(2) bond lengths. In the third Sm site, Sm(3) is bonded in a 12-coordinate geometry to twelve equivalent Fe(1) atoms. All Sm(3)-Fe(1) bond lengths are 3.06 Å. Fe(1) is bonded in a distorted trigonal non-coplanar geometry to one Sm(3), one C(1), and two equivalent C(2) atoms. The Fe(1)-C(1) bond length is 1.97 Å. Both Fe(1)-C(2) bond lengths are 1.82 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a 7-coordinate geometry to four equivalent Sm(1), two equivalent Fe(1), and one C(1) atom. The C(1)-C(1) bond length is 1.40 Å. In the second C site, C(2) is bonded to two equivalent Sm(1), two equivalent Sm(2), and two equivalent Fe(1) atoms to form a mixture of distorted corner and edge-sharing CSm4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-72°.