Y6Fe16O crystallizes in the cubic Im-3m space group. Y(1) is bonded in a single-bond geometry to four equivalent Fe(1), eight equivalent Fe(2), and one O(1) atom. There are two inequivalent Fe sites. In the first Fe site, Fe(2) is bonded to four equivalent Y(1), two equivalent Fe(1), and six equivalent Fe(2) atoms to form distorted FeY4Fe8 cuboctahedra that share corners with six equivalent Fe(1)Y6Fe6 cuboctahedra, corners with eight equivalent Fe(2)Y4Fe8 cuboctahedra, corners with two equivalent O(1)Y6 octahedra, edges with eight equivalent Fe(2)Y4Fe8 cuboctahedra,  an edgeedge with one O(1)Y6 octahedra, faces with six equivalent Fe(1)Y6Fe6 cuboctahedra, and faces with eleven equivalent Fe(2)Y4Fe8 cuboctahedra. The corner-sharing octahedral tilt angles are 44°. In the second Fe site, Fe(1) is bonded to six equivalent Y(1) and six equivalent Fe(2) atoms to form FeY6Fe6 cuboctahedra that share corners with six equivalent Fe(1)Y6Fe6 cuboctahedra, corners with eighteen equivalent Fe(2)Y4Fe8 cuboctahedra, faces with six equivalent Fe(1)Y6Fe6 cuboctahedra, faces with eighteen equivalent Fe(2)Y4Fe8 cuboctahedra, and faces with two equivalent O(1)Y6 octahedra. O(1) is bonded to six equivalent Y(1) atoms to form OY6 octahedra that share corners with twenty-four equivalent Fe(2)Y4Fe8 cuboctahedra, edges with twelve equivalent Fe(2)Y4Fe8 cuboctahedra, and faces with eight equivalent Fe(1)Y6Fe6 cuboctahedra.
Y6Fe16O crystallizes in the cubic Im-3m space group. Y(1) is bonded in a single-bond geometry to four equivalent Fe(1), eight equivalent Fe(2), and one O(1) atom. All Y(1)-Fe(1) bond lengths are 3.35 Å. There are four shorter (3.12 Å) and four longer (3.27 Å) Y(1)-Fe(2) bond lengths. The Y(1)-O(1) bond length is 2.48 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(2) is bonded to four equivalent Y(1), two equivalent Fe(1), and six equivalent Fe(2) atoms to form distorted FeY4Fe8 cuboctahedra that share corners with six equivalent Fe(1)Y6Fe6 cuboctahedra, corners with eight equivalent Fe(2)Y4Fe8 cuboctahedra, corners with two equivalent O(1)Y6 octahedra, edges with eight equivalent Fe(2)Y4Fe8 cuboctahedra,  an edgeedge with one O(1)Y6 octahedra, faces with six equivalent Fe(1)Y6Fe6 cuboctahedra, and faces with eleven equivalent Fe(2)Y4Fe8 cuboctahedra. The corner-sharing octahedral tilt angles are 44°. Both Fe(2)-Fe(1) bond lengths are 2.64 Å. There are four shorter (2.73 Å) and two longer (3.07 Å) Fe(2)-Fe(2) bond lengths. In the second Fe site, Fe(1) is bonded to six equivalent Y(1) and six equivalent Fe(2) atoms to form FeY6Fe6 cuboctahedra that share corners with six equivalent Fe(1)Y6Fe6 cuboctahedra, corners with eighteen equivalent Fe(2)Y4Fe8 cuboctahedra, faces with six equivalent Fe(1)Y6Fe6 cuboctahedra, faces with eighteen equivalent Fe(2)Y4Fe8 cuboctahedra, and faces with two equivalent O(1)Y6 octahedra. O(1) is bonded to six equivalent Y(1) atoms to form OY6 octahedra that share corners with twenty-four equivalent Fe(2)Y4Fe8 cuboctahedra, edges with twelve equivalent Fe(2)Y4Fe8 cuboctahedra, and faces with eight equivalent Fe(1)Y6Fe6 cuboctahedra.