Dy2Fe17 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 18-coordinate geometry to six equivalent Fe(3) and twelve equivalent Fe(4) atoms. In the second Dy site, Dy(2) is bonded in a 20-coordinate geometry to two equivalent Fe(1), six equivalent Fe(2), six equivalent Fe(3), and six equivalent Fe(4) atoms. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 14-coordinate geometry to one Dy(2), one Fe(1), three equivalent Fe(2), three equivalent Fe(4), and six equivalent Fe(3) atoms. In the second Fe site, Fe(2) is bonded to two equivalent Dy(2), two equivalent Fe(1), four equivalent Fe(3), and four equivalent Fe(4) atoms to form FeDy2Fe10 cuboctahedra that share corners with four equivalent Fe(2)Dy2Fe10 cuboctahedra, corners with ten equivalent Fe(4)Dy3Fe9 cuboctahedra, edges with six equivalent Fe(4)Dy3Fe9 cuboctahedra, faces with four equivalent Fe(4)Dy3Fe9 cuboctahedra, and faces with six equivalent Fe(2)Dy2Fe10 cuboctahedra. In the third Fe site, Fe(3) is bonded in a 12-coordinate geometry to one Dy(1), one Dy(2), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), and four equivalent Fe(4) atoms. In the fourth Fe site, Fe(4) is bonded to one Dy(2), two equivalent Dy(1), one Fe(1), two equivalent Fe(2), two equivalent Fe(4), and four equivalent Fe(3) atoms to form distorted FeDy3Fe9 cuboctahedra that share corners with five equivalent Fe(2)Dy2Fe10 cuboctahedra, corners with ten equivalent Fe(4)Dy3Fe9 cuboctahedra, edges with three equivalent Fe(2)Dy2Fe10 cuboctahedra, edges with five equivalent Fe(4)Dy3Fe9 cuboctahedra, faces with two equivalent Fe(2)Dy2Fe10 cuboctahedra, and faces with eight equivalent Fe(4)Dy3Fe9 cuboctahedra.
Dy2Fe17 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 18-coordinate geometry to six equivalent Fe(3) and twelve equivalent Fe(4) atoms. All Dy(1)-Fe(3) bond lengths are 2.99 Å. There are six shorter (3.11 Å) and six longer (3.28 Å) Dy(1)-Fe(4) bond lengths. In the second Dy site, Dy(2) is bonded in a 20-coordinate geometry to two equivalent Fe(1), six equivalent Fe(2), six equivalent Fe(3), and six equivalent Fe(4) atoms. Both Dy(2)-Fe(1) bond lengths are 2.93 Å. All Dy(2)-Fe(2) bond lengths are 3.20 Å. All Dy(2)-Fe(3) bond lengths are 3.04 Å. All Dy(2)-Fe(4) bond lengths are 3.13 Å. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 14-coordinate geometry to one Dy(2), one Fe(1), three equivalent Fe(2), three equivalent Fe(4), and six equivalent Fe(3) atoms. The Fe(1)-Fe(1) bond length is 2.37 Å. All Fe(1)-Fe(2) bond lengths are 2.61 Å. All Fe(1)-Fe(4) bond lengths are 2.66 Å. All Fe(1)-Fe(3) bond lengths are 2.78 Å. In the second Fe site, Fe(2) is bonded to two equivalent Dy(2), two equivalent Fe(1), four equivalent Fe(3), and four equivalent Fe(4) atoms to form FeDy2Fe10 cuboctahedra that share corners with four equivalent Fe(2)Dy2Fe10 cuboctahedra, corners with ten equivalent Fe(4)Dy3Fe9 cuboctahedra, edges with six equivalent Fe(4)Dy3Fe9 cuboctahedra, faces with four equivalent Fe(4)Dy3Fe9 cuboctahedra, and faces with six equivalent Fe(2)Dy2Fe10 cuboctahedra. All Fe(2)-Fe(3) bond lengths are 2.44 Å. All Fe(2)-Fe(4) bond lengths are 2.46 Å. In the third Fe site, Fe(3) is bonded in a 12-coordinate geometry to one Dy(1), one Dy(2), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), and four equivalent Fe(4) atoms. There is one shorter (2.46 Å) and one longer (2.57 Å) Fe(3)-Fe(3) bond length. There are two shorter (2.52 Å) and two longer (2.60 Å) Fe(3)-Fe(4) bond lengths. In the fourth Fe site, Fe(4) is bonded to one Dy(2), two equivalent Dy(1), one Fe(1), two equivalent Fe(2), two equivalent Fe(4), and four equivalent Fe(3) atoms to form distorted FeDy3Fe9 cuboctahedra that share corners with five equivalent Fe(2)Dy2Fe10 cuboctahedra, corners with ten equivalent Fe(4)Dy3Fe9 cuboctahedra, edges with three equivalent Fe(2)Dy2Fe10 cuboctahedra, edges with five equivalent Fe(4)Dy3Fe9 cuboctahedra, faces with two equivalent Fe(2)Dy2Fe10 cuboctahedra, and faces with eight equivalent Fe(4)Dy3Fe9 cuboctahedra. Both Fe(4)-Fe(4) bond lengths are 2.46 Å.