Fe6W6C crystallizes in the cubic Fd-3m space group. W(1) is bonded in a 7-coordinate geometry to two equivalent Fe(2), four equivalent Fe(1), and one C(1) atom. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 12-coordinate geometry to six equivalent W(1), three equivalent Fe(1), and three equivalent Fe(2) atoms. In the second Fe site, Fe(2) is bonded to six equivalent W(1) and six equivalent Fe(1) atoms to form FeFe6W6 cuboctahedra that share corners with six equivalent C(1)W6 octahedra and faces with six equivalent Fe(2)Fe6W6 cuboctahedra. The corner-sharing octahedral tilt angles are 45°. C(1) is bonded to six equivalent W(1) atoms to form CW6 octahedra that share corners with twelve equivalent Fe(2)Fe6W6 cuboctahedra.
Fe6W6C crystallizes in the cubic Fd-3m space group. W(1) is bonded in a 7-coordinate geometry to two equivalent Fe(2), four equivalent Fe(1), and one C(1) atom. Both W(1)-Fe(2) bond lengths are 2.78 Å. There are two shorter (2.64 Å) and two longer (2.77 Å) W(1)-Fe(1) bond lengths. The W(1)-C(1) bond length is 2.15 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 12-coordinate geometry to six equivalent W(1), three equivalent Fe(1), and three equivalent Fe(2) atoms. All Fe(1)-Fe(1) bond lengths are 2.54 Å. All Fe(1)-Fe(2) bond lengths are 2.38 Å. In the second Fe site, Fe(2) is bonded to six equivalent W(1) and six equivalent Fe(1) atoms to form FeFe6W6 cuboctahedra that share corners with six equivalent C(1)W6 octahedra and faces with six equivalent Fe(2)Fe6W6 cuboctahedra. The corner-sharing octahedral tilt angles are 45°. C(1) is bonded to six equivalent W(1) atoms to form CW6 octahedra that share corners with twelve equivalent Fe(2)Fe6W6 cuboctahedra.