Th2Fe17C crystallizes in the monoclinic C2/m space group. Th(1) is bonded in a distorted single-bond geometry to one Fe(3), one Fe(5), two equivalent Fe(4), four equivalent Fe(7), six equivalent Fe(1), and one C(1) atom. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent Th(1), one Fe(1), one Fe(2), one Fe(3), one Fe(4), one Fe(5), one Fe(6), and three equivalent Fe(7) atoms to form distorted FeTh3Fe9 cuboctahedra that share  a cornercorner with one Fe(3)Th2Fe10 cuboctahedra, corners with four equivalent Fe(4)Th2Fe10 cuboctahedra, corners with five equivalent Fe(7)Th2Fe10 cuboctahedra, corners with seven equivalent Fe(1)Th3Fe9 cuboctahedra, corners with two equivalent C(1)Th2Fe4 octahedra,  an edgeedge with one Fe(3)Th2Fe10 cuboctahedra,  an edgeedge with one Fe(7)Th2Fe10 cuboctahedra, edges with two equivalent Fe(4)Th2Fe10 cuboctahedra, edges with three equivalent Fe(1)Th3Fe9 cuboctahedra,  a faceface with one Fe(3)Th2Fe10 cuboctahedra, faces with two equivalent Fe(4)Th2Fe10 cuboctahedra, faces with four equivalent Fe(1)Th3Fe9 cuboctahedra, faces with seven equivalent Fe(7)Th2Fe10 cuboctahedra, and  a faceface with one C(1)Th2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 66-70°. In the second Fe site, Fe(2) is bonded in a single-bond geometry to one Fe(5), two equivalent Fe(1), two equivalent Fe(4), two equivalent Fe(7), and one C(1) atom. In the third Fe site, Fe(3) is bonded to two equivalent Th(1), two equivalent Fe(5), four equivalent Fe(1), and four equivalent Fe(7) atoms to form FeTh2Fe10 cuboctahedra that share corners with four equivalent Fe(4)Th2Fe10 cuboctahedra, corners with four equivalent Fe(7)Th2Fe10 cuboctahedra, corners with four equivalent Fe(1)Th3Fe9 cuboctahedra, corners with two equivalent C(1)Th2Fe4 octahedra, edges with four equivalent Fe(7)Th2Fe10 cuboctahedra, edges with four equivalent Fe(1)Th3Fe9 cuboctahedra, faces with four equivalent Fe(4)Th2Fe10 cuboctahedra, faces with four equivalent Fe(7)Th2Fe10 cuboctahedra, and faces with four equivalent Fe(1)Th3Fe9 cuboctahedra. The corner-sharing octahedral tilt angles are 44°. In the fourth Fe site, Fe(4) is bonded to two equivalent Th(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(5), two equivalent Fe(6), and two equivalent Fe(7) atoms to form distorted FeTh2Fe10 cuboctahedra that share corners with two equivalent Fe(3)Th2Fe10 cuboctahedra, corners with two equivalent Fe(4)Th2Fe10 cuboctahedra, corners with six equivalent Fe(7)Th2Fe10 cuboctahedra, corners with eight equivalent Fe(1)Th3Fe9 cuboctahedra, edges with two equivalent Fe(7)Th2Fe10 cuboctahedra, edges with four equivalent Fe(1)Th3Fe9 cuboctahedra, faces with two equivalent Fe(3)Th2Fe10 cuboctahedra, faces with two equivalent Fe(4)Th2Fe10 cuboctahedra, faces with four equivalent Fe(1)Th3Fe9 cuboctahedra, faces with six equivalent Fe(7)Th2Fe10 cuboctahedra, and faces with two equivalent C(1)Th2Fe4 octahedra. In the fifth Fe site, Fe(5) is bonded in a 14-coordinate geometry to one Th(1), one Fe(2), one Fe(3), one Fe(5), two equivalent Fe(1), two equivalent Fe(4), two equivalent Fe(6), and four equivalent Fe(7) atoms. In the sixth Fe site, Fe(6) is bonded in a single-bond geometry to two equivalent Fe(1), two equivalent Fe(4), two equivalent Fe(5), two equivalent Fe(7), and one C(1) atom. In the seventh Fe site, Fe(7) is bonded to two equivalent Th(1), one Fe(2), one Fe(3), one Fe(4), one Fe(6), one Fe(7), two equivalent Fe(5), and three equivalent Fe(1) atoms to form distorted FeTh2Fe10 cuboctahedra that share  a cornercorner with one Fe(3)Th2Fe10 cuboctahedra, corners with three equivalent Fe(4)Th2Fe10 cuboctahedra, corners with five equivalent Fe(1)Th3Fe9 cuboctahedra, corners with seven equivalent Fe(7)Th2Fe10 cuboctahedra, corners with two equivalent C(1)Th2Fe4 octahedra,  an edgeedge with one Fe(3)Th2Fe10 cuboctahedra,  an edgeedge with one Fe(4)Th2Fe10 cuboctahedra,  an edgeedge with one Fe(7)Th2Fe10 cuboctahedra,  an edgeedge with one Fe(1)Th3Fe9 cuboctahedra,  an edgeedge with one C(1)Th2Fe4 octahedra,  a faceface with one Fe(3)Th2Fe10 cuboctahedra, faces with three equivalent Fe(4)Th2Fe10 cuboctahedra, faces with four equivalent Fe(7)Th2Fe10 cuboctahedra, and faces with seven equivalent Fe(1)Th3Fe9 cuboctahedra. The corner-sharing octahedral tilt angles range from 24-30°. C(1) is bonded to two equivalent Th(1), two equivalent Fe(2), and two equivalent Fe(6) atoms to form CTh2Fe4 octahedra that share corners with two equivalent Fe(3)Th2Fe10 cuboctahedra, corners with eight equivalent Fe(7)Th2Fe10 cuboctahedra, corners with eight equivalent Fe(1)Th3Fe9 cuboctahedra, edges with four equivalent Fe(7)Th2Fe10 cuboctahedra, faces with four equivalent Fe(4)Th2Fe10 cuboctahedra, and faces with four equivalent Fe(1)Th3Fe9 cuboctahedra.
Th2Fe17C crystallizes in the monoclinic C2/m space group. Th(1) is bonded in a distorted single-bond geometry to one Fe(3), one Fe(5), two equivalent Fe(4), four equivalent Fe(7), six equivalent Fe(1), and one C(1) atom. The Th(1)-Fe(3) bond length is 3.25 Å. The Th(1)-Fe(5) bond length is 3.05 Å. Both Th(1)-Fe(4) bond lengths are 3.34 Å. There are two shorter (3.06 Å) and two longer (3.12 Å) Th(1)-Fe(7) bond lengths. There are a spread of Th(1)-Fe(1) bond distances ranging from 3.08-3.34 Å. The Th(1)-C(1) bond length is 2.62 Å. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent Th(1), one Fe(1), one Fe(2), one Fe(3), one Fe(4), one Fe(5), one Fe(6), and three equivalent Fe(7) atoms to form distorted FeTh3Fe9 cuboctahedra that share  a cornercorner with one Fe(3)Th2Fe10 cuboctahedra, corners with four equivalent Fe(4)Th2Fe10 cuboctahedra, corners with five equivalent Fe(7)Th2Fe10 cuboctahedra, corners with seven equivalent Fe(1)Th3Fe9 cuboctahedra, corners with two equivalent C(1)Th2Fe4 octahedra,  an edgeedge with one Fe(3)Th2Fe10 cuboctahedra,  an edgeedge with one Fe(7)Th2Fe10 cuboctahedra, edges with two equivalent Fe(4)Th2Fe10 cuboctahedra, edges with three equivalent Fe(1)Th3Fe9 cuboctahedra,  a faceface with one Fe(3)Th2Fe10 cuboctahedra, faces with two equivalent Fe(4)Th2Fe10 cuboctahedra, faces with four equivalent Fe(1)Th3Fe9 cuboctahedra, faces with seven equivalent Fe(7)Th2Fe10 cuboctahedra, and  a faceface with one C(1)Th2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 66-70°. The Fe(1)-Fe(1) bond length is 2.56 Å. The Fe(1)-Fe(2) bond length is 2.55 Å. The Fe(1)-Fe(3) bond length is 2.48 Å. The Fe(1)-Fe(4) bond length is 2.50 Å. The Fe(1)-Fe(5) bond length is 2.66 Å. The Fe(1)-Fe(6) bond length is 2.55 Å. There are a spread of Fe(1)-Fe(7) bond distances ranging from 2.54-2.71 Å. In the second Fe site, Fe(2) is bonded in a single-bond geometry to one Fe(5), two equivalent Fe(1), two equivalent Fe(4), two equivalent Fe(7), and one C(1) atom. The Fe(2)-Fe(5) bond length is 2.69 Å. Both Fe(2)-Fe(4) bond lengths are 2.48 Å. Both Fe(2)-Fe(7) bond lengths are 2.56 Å. The Fe(2)-C(1) bond length is 1.92 Å. In the third Fe site, Fe(3) is bonded to two equivalent Th(1), two equivalent Fe(5), four equivalent Fe(1), and four equivalent Fe(7) atoms to form FeTh2Fe10 cuboctahedra that share corners with four equivalent Fe(4)Th2Fe10 cuboctahedra, corners with four equivalent Fe(7)Th2Fe10 cuboctahedra, corners with four equivalent Fe(1)Th3Fe9 cuboctahedra, corners with two equivalent C(1)Th2Fe4 octahedra, edges with four equivalent Fe(7)Th2Fe10 cuboctahedra, edges with four equivalent Fe(1)Th3Fe9 cuboctahedra, faces with four equivalent Fe(4)Th2Fe10 cuboctahedra, faces with four equivalent Fe(7)Th2Fe10 cuboctahedra, and faces with four equivalent Fe(1)Th3Fe9 cuboctahedra. The corner-sharing octahedral tilt angles are 44°. Both Fe(3)-Fe(5) bond lengths are 2.66 Å. All Fe(3)-Fe(7) bond lengths are 2.43 Å. In the fourth Fe site, Fe(4) is bonded to two equivalent Th(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(5), two equivalent Fe(6), and two equivalent Fe(7) atoms to form distorted FeTh2Fe10 cuboctahedra that share corners with two equivalent Fe(3)Th2Fe10 cuboctahedra, corners with two equivalent Fe(4)Th2Fe10 cuboctahedra, corners with six equivalent Fe(7)Th2Fe10 cuboctahedra, corners with eight equivalent Fe(1)Th3Fe9 cuboctahedra, edges with two equivalent Fe(7)Th2Fe10 cuboctahedra, edges with four equivalent Fe(1)Th3Fe9 cuboctahedra, faces with two equivalent Fe(3)Th2Fe10 cuboctahedra, faces with two equivalent Fe(4)Th2Fe10 cuboctahedra, faces with four equivalent Fe(1)Th3Fe9 cuboctahedra, faces with six equivalent Fe(7)Th2Fe10 cuboctahedra, and faces with two equivalent C(1)Th2Fe4 octahedra. Both Fe(4)-Fe(5) bond lengths are 2.65 Å. Both Fe(4)-Fe(6) bond lengths are 2.44 Å. Both Fe(4)-Fe(7) bond lengths are 2.43 Å. In the fifth Fe site, Fe(5) is bonded in a 14-coordinate geometry to one Th(1), one Fe(2), one Fe(3), one Fe(5), two equivalent Fe(1), two equivalent Fe(4), two equivalent Fe(6), and four equivalent Fe(7) atoms. The Fe(5)-Fe(5) bond length is 2.38 Å. Both Fe(5)-Fe(6) bond lengths are 2.72 Å. There are two shorter (2.72 Å) and two longer (2.73 Å) Fe(5)-Fe(7) bond lengths. In the sixth Fe site, Fe(6) is bonded in a single-bond geometry to two equivalent Fe(1), two equivalent Fe(4), two equivalent Fe(5), two equivalent Fe(7), and one C(1) atom. Both Fe(6)-Fe(7) bond lengths are 2.45 Å. The Fe(6)-C(1) bond length is 1.86 Å. In the seventh Fe site, Fe(7) is bonded to two equivalent Th(1), one Fe(2), one Fe(3), one Fe(4), one Fe(6), one Fe(7), two equivalent Fe(5), and three equivalent Fe(1) atoms to form distorted FeTh2Fe10 cuboctahedra that share  a cornercorner with one Fe(3)Th2Fe10 cuboctahedra, corners with three equivalent Fe(4)Th2Fe10 cuboctahedra, corners with five equivalent Fe(1)Th3Fe9 cuboctahedra, corners with seven equivalent Fe(7)Th2Fe10 cuboctahedra, corners with two equivalent C(1)Th2Fe4 octahedra,  an edgeedge with one Fe(3)Th2Fe10 cuboctahedra,  an edgeedge with one Fe(4)Th2Fe10 cuboctahedra,  an edgeedge with one Fe(7)Th2Fe10 cuboctahedra,  an edgeedge with one Fe(1)Th3Fe9 cuboctahedra,  an edgeedge with one C(1)Th2Fe4 octahedra,  a faceface with one Fe(3)Th2Fe10 cuboctahedra, faces with three equivalent Fe(4)Th2Fe10 cuboctahedra, faces with four equivalent Fe(7)Th2Fe10 cuboctahedra, and faces with seven equivalent Fe(1)Th3Fe9 cuboctahedra. The corner-sharing octahedral tilt angles range from 24-30°. The Fe(7)-Fe(7) bond length is 2.45 Å. C(1) is bonded to two equivalent Th(1), two equivalent Fe(2), and two equivalent Fe(6) atoms to form CTh2Fe4 octahedra that share corners with two equivalent Fe(3)Th2Fe10 cuboctahedra, corners with eight equivalent Fe(7)Th2Fe10 cuboctahedra, corners with eight equivalent Fe(1)Th3Fe9 cuboctahedra, edges with four equivalent Fe(7)Th2Fe10 cuboctahedra, faces with four equivalent Fe(4)Th2Fe10 cuboctahedra, and faces with four equivalent Fe(1)Th3Fe9 cuboctahedra.