Y2Fe17C crystallizes in the monoclinic C2/m space group. Y(1) is bonded in a distorted single-bond geometry to one Fe(3), one Fe(4), two equivalent Fe(5), four equivalent Fe(7), six equivalent Fe(2), and one C(1) atom. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a single-bond geometry to one Fe(3), two equivalent Fe(2), two equivalent Fe(5), two equivalent Fe(7), and one C(1) atom. In the second Fe site, Fe(2) is bonded to three equivalent Y(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 FeY3Fe9 cuboctahedra that share  a cornercorner with one Fe(4)Y2Fe10 cuboctahedra, corners with four equivalent Fe(5)Y2Fe10 cuboctahedra, corners with seven equivalent Fe(2)Y3Fe9 cuboctahedra, corners with two equivalent C(1)Y2Fe4 octahedra,  an edgeedge with one Fe(4)Y2Fe10 cuboctahedra, edges with two equivalent Fe(5)Y2Fe10 cuboctahedra, edges with three equivalent Fe(2)Y3Fe9 cuboctahedra,  a faceface with one Fe(4)Y2Fe10 cuboctahedra, faces with two equivalent Fe(5)Y2Fe10 cuboctahedra, faces with four equivalent Fe(2)Y3Fe9 cuboctahedra, and  a faceface with one C(1)Y2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 65-70°. In the third Fe site, Fe(3) is bonded in a 14-coordinate geometry to one Y(1), one Fe(1), one Fe(3), one Fe(4), two equivalent Fe(2), two equivalent Fe(5), two equivalent Fe(6), and four equivalent Fe(7) atoms. In the fourth Fe site, Fe(4) is bonded to two equivalent Y(1), two equivalent Fe(3), four equivalent Fe(2), and four equivalent Fe(7) atoms to form FeY2Fe10 cuboctahedra that share corners with four equivalent Fe(5)Y2Fe10 cuboctahedra, corners with four equivalent Fe(2)Y3Fe9 cuboctahedra, corners with two equivalent C(1)Y2Fe4 octahedra, edges with four equivalent Fe(2)Y3Fe9 cuboctahedra, faces with four equivalent Fe(5)Y2Fe10 cuboctahedra, and faces with four equivalent Fe(2)Y3Fe9 cuboctahedra. The corner-sharing octahedral tilt angles are 45°. In the fifth Fe site, Fe(5) is bonded to two equivalent Y(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(6), and two equivalent Fe(7) atoms to form distorted FeY2Fe10 cuboctahedra that share corners with two equivalent Fe(4)Y2Fe10 cuboctahedra, corners with two equivalent Fe(5)Y2Fe10 cuboctahedra, corners with eight equivalent Fe(2)Y3Fe9 cuboctahedra, edges with four equivalent Fe(2)Y3Fe9 cuboctahedra, faces with two equivalent Fe(4)Y2Fe10 cuboctahedra, faces with two equivalent Fe(5)Y2Fe10 cuboctahedra, faces with four equivalent Fe(2)Y3Fe9 cuboctahedra, and faces with two equivalent C(1)Y2Fe4 octahedra. In the sixth Fe site, Fe(6) is bonded in a single-bond geometry to two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(5), two equivalent Fe(7), and one C(1) atom. In the seventh Fe site, Fe(7) is bonded in a 12-coordinate geometry to two equivalent Y(1), one Fe(1), one Fe(4), one Fe(5), one Fe(6), one Fe(7), two equivalent Fe(3), and three equivalent Fe(2) atoms. C(1) is bonded to two equivalent Y(1), two equivalent Fe(1), and two equivalent Fe(6) atoms to form CY2Fe4 octahedra that share corners with two equivalent Fe(4)Y2Fe10 cuboctahedra, corners with eight equivalent Fe(2)Y3Fe9 cuboctahedra, faces with four equivalent Fe(5)Y2Fe10 cuboctahedra, and faces with four equivalent Fe(2)Y3Fe9 cuboctahedra.
Y2Fe17C crystallizes in the monoclinic C2/m space group. Y(1) is bonded in a distorted single-bond geometry to one Fe(3), one Fe(4), two equivalent Fe(5), four equivalent Fe(7), six equivalent Fe(2), and one C(1) atom. The Y(1)-Fe(3) bond length is 3.06 Å. The Y(1)-Fe(4) bond length is 3.26 Å. Both Y(1)-Fe(5) bond lengths are 3.33 Å. There are two shorter (3.00 Å) and two longer (3.07 Å) Y(1)-Fe(7) bond lengths. There are a spread of Y(1)-Fe(2) bond distances ranging from 3.07-3.29 Å. The Y(1)-C(1) bond length is 2.52 Å. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a single-bond geometry to one Fe(3), two equivalent Fe(2), two equivalent Fe(5), two equivalent Fe(7), and one C(1) atom. The Fe(1)-Fe(3) bond length is 2.64 Å. Both Fe(1)-Fe(2) bond lengths are 2.53 Å. Both Fe(1)-Fe(5) bond lengths are 2.47 Å. Both Fe(1)-Fe(7) bond lengths are 2.56 Å. The Fe(1)-C(1) bond length is 1.92 Å. In the second Fe site, Fe(2) is bonded to three equivalent Y(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 FeY3Fe9 cuboctahedra that share  a cornercorner with one Fe(4)Y2Fe10 cuboctahedra, corners with four equivalent Fe(5)Y2Fe10 cuboctahedra, corners with seven equivalent Fe(2)Y3Fe9 cuboctahedra, corners with two equivalent C(1)Y2Fe4 octahedra,  an edgeedge with one Fe(4)Y2Fe10 cuboctahedra, edges with two equivalent Fe(5)Y2Fe10 cuboctahedra, edges with three equivalent Fe(2)Y3Fe9 cuboctahedra,  a faceface with one Fe(4)Y2Fe10 cuboctahedra, faces with two equivalent Fe(5)Y2Fe10 cuboctahedra, faces with four equivalent Fe(2)Y3Fe9 cuboctahedra, and  a faceface with one C(1)Y2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 65-70°. The Fe(2)-Fe(2) bond length is 2.50 Å. The Fe(2)-Fe(3) bond length is 2.64 Å. The Fe(2)-Fe(4) bond length is 2.45 Å. The Fe(2)-Fe(5) bond length is 2.45 Å. The Fe(2)-Fe(6) bond length is 2.55 Å. There are a spread of Fe(2)-Fe(7) bond distances ranging from 2.55-2.63 Å. In the third Fe site, Fe(3) is bonded in a 14-coordinate geometry to one Y(1), one Fe(1), one Fe(3), one Fe(4), two equivalent Fe(2), two equivalent Fe(5), two equivalent Fe(6), and four equivalent Fe(7) atoms. The Fe(3)-Fe(3) bond length is 2.41 Å. The Fe(3)-Fe(4) bond length is 2.61 Å. Both Fe(3)-Fe(5) bond lengths are 2.62 Å. Both Fe(3)-Fe(6) bond lengths are 2.74 Å. All Fe(3)-Fe(7) bond lengths are 2.76 Å. In the fourth Fe site, Fe(4) is bonded to two equivalent Y(1), two equivalent Fe(3), four equivalent Fe(2), and four equivalent Fe(7) atoms to form FeY2Fe10 cuboctahedra that share corners with four equivalent Fe(5)Y2Fe10 cuboctahedra, corners with four equivalent Fe(2)Y3Fe9 cuboctahedra, corners with two equivalent C(1)Y2Fe4 octahedra, edges with four equivalent Fe(2)Y3Fe9 cuboctahedra, faces with four equivalent Fe(5)Y2Fe10 cuboctahedra, and faces with four equivalent Fe(2)Y3Fe9 cuboctahedra. The corner-sharing octahedral tilt angles are 45°. All Fe(4)-Fe(7) bond lengths are 2.44 Å. In the fifth Fe site, Fe(5) is bonded to two equivalent Y(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(6), and two equivalent Fe(7) atoms to form distorted FeY2Fe10 cuboctahedra that share corners with two equivalent Fe(4)Y2Fe10 cuboctahedra, corners with two equivalent Fe(5)Y2Fe10 cuboctahedra, corners with eight equivalent Fe(2)Y3Fe9 cuboctahedra, edges with four equivalent Fe(2)Y3Fe9 cuboctahedra, faces with two equivalent Fe(4)Y2Fe10 cuboctahedra, faces with two equivalent Fe(5)Y2Fe10 cuboctahedra, faces with four equivalent Fe(2)Y3Fe9 cuboctahedra, and faces with two equivalent C(1)Y2Fe4 octahedra. Both Fe(5)-Fe(6) bond lengths are 2.43 Å. Both Fe(5)-Fe(7) bond lengths are 2.43 Å. In the sixth Fe site, Fe(6) is bonded in a single-bond geometry to two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(5), two equivalent Fe(7), and one C(1) atom. Both Fe(6)-Fe(7) bond lengths are 2.46 Å. The Fe(6)-C(1) bond length is 1.84 Å. In the seventh Fe site, Fe(7) is bonded in a 12-coordinate geometry to two equivalent Y(1), one Fe(1), one Fe(4), one Fe(5), one Fe(6), one Fe(7), two equivalent Fe(3), and three equivalent Fe(2) atoms. The Fe(7)-Fe(7) bond length is 2.50 Å. C(1) is bonded to two equivalent Y(1), two equivalent Fe(1), and two equivalent Fe(6) atoms to form CY2Fe4 octahedra that share corners with two equivalent Fe(4)Y2Fe10 cuboctahedra, corners with eight equivalent Fe(2)Y3Fe9 cuboctahedra, faces with four equivalent Fe(5)Y2Fe10 cuboctahedra, and faces with four equivalent Fe(2)Y3Fe9 cuboctahedra.