U6Fe16Si7C crystallizes in the cubic Fm-3m space group. U(1) is bonded in a distorted single-bond geometry to four equivalent Fe(1), four equivalent Fe(2), four equivalent Si(1), and one C(1) atom. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 13-coordinate geometry to three equivalent U(1), three equivalent Fe(1), three equivalent Fe(2), one Si(2), and three equivalent Si(1) atoms. In the second Fe site, Fe(2) is bonded in a 12-coordinate geometry to three equivalent U(1), three equivalent Fe(1), three equivalent Fe(2), and three equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(2) is bonded in a body-centered cubic geometry to eight equivalent Fe(1) atoms. In the second Si site, Si(1) is bonded to four equivalent U(1), four equivalent Fe(1), and four equivalent Fe(2) atoms to form SiU4Fe8 cuboctahedra that share corners with four equivalent Si(1)U4Fe8 cuboctahedra, edges with two equivalent C(1)U6 octahedra, and faces with eight equivalent Si(1)U4Fe8 cuboctahedra. C(1) is bonded to six equivalent U(1) atoms to form CU6 octahedra that share edges with twelve equivalent Si(1)U4Fe8 cuboctahedra.
U6Fe16Si7C crystallizes in the cubic Fm-3m space group. U(1) is bonded in a distorted single-bond geometry to four equivalent Fe(1), four equivalent Fe(2), four equivalent Si(1), and one C(1) atom. All U(1)-Fe(1) bond lengths are 2.76 Å. All U(1)-Fe(2) bond lengths are 2.91 Å. All U(1)-Si(1) bond lengths are 2.93 Å. The U(1)-C(1) bond length is 2.49 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 13-coordinate geometry to three equivalent U(1), three equivalent Fe(1), three equivalent Fe(2), one Si(2), and three equivalent Si(1) atoms. All Fe(1)-Fe(1) bond lengths are 2.84 Å. All Fe(1)-Fe(2) bond lengths are 2.50 Å. The Fe(1)-Si(2) bond length is 2.46 Å. All Fe(1)-Si(1) bond lengths are 2.53 Å. In the second Fe site, Fe(2) is bonded in a 12-coordinate geometry to three equivalent U(1), three equivalent Fe(1), three equivalent Fe(2), and three equivalent Si(1) atoms. All Fe(2)-Fe(2) bond lengths are 2.47 Å. All Fe(2)-Si(1) bond lengths are 2.37 Å. There are two inequivalent Si sites. In the first Si site, Si(2) is bonded in a body-centered cubic geometry to eight equivalent Fe(1) atoms. In the second Si site, Si(1) is bonded to four equivalent U(1), four equivalent Fe(1), and four equivalent Fe(2) atoms to form SiU4Fe8 cuboctahedra that share corners with four equivalent Si(1)U4Fe8 cuboctahedra, edges with two equivalent C(1)U6 octahedra, and faces with eight equivalent Si(1)U4Fe8 cuboctahedra. C(1) is bonded to six equivalent U(1) atoms to form CU6 octahedra that share edges with twelve equivalent Si(1)U4Fe8 cuboctahedra.