Er4Y2Fe23 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 12-coordinate geometry to one Fe(1), one Fe(2), one Fe(5), one Fe(6), two equivalent Fe(3), two equivalent Fe(7), and four equivalent Fe(8) atoms. In the second Er site, Er(2) is bonded in a 12-coordinate geometry to one Fe(10), one Fe(9), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(6), two equivalent Fe(7), and two equivalent Fe(8) atoms. Y(1) is bonded in a 12-coordinate geometry to one Fe(10), one Fe(9), two equivalent Fe(1), two equivalent Fe(3), two equivalent Fe(5), two equivalent Fe(7), and two equivalent Fe(8) atoms. There are ten inequivalent Fe sites. In the first Fe site, Fe(10) is bonded to two equivalent Er(2), two equivalent Y(1), two equivalent Fe(1), two equivalent Fe(2), and four equivalent Fe(7) atoms to form FeY2Er2Fe8 cuboctahedra that share corners with four equivalent Fe(9)Y2Er2Fe8 cuboctahedra and faces with eight equivalent Fe(8)YEr3Fe8 cuboctahedra. In the second Fe site, Fe(1) is bonded in a distorted q6 geometry to one Er(1), two equivalent Y(1), one Fe(10), one Fe(2), one Fe(6), two equivalent Fe(3), two equivalent Fe(7), and two equivalent Fe(8) atoms. In the third Fe site, Fe(2) is bonded in a distorted q6 geometry to one Er(1), two equivalent Er(2), one Fe(1), one Fe(10), one Fe(5), two equivalent Fe(3), two equivalent Fe(7), and two equivalent Fe(8) atoms. In the fourth Fe site, Fe(3) is bonded in a distorted q6 geometry to one Er(1), one Er(2), one Y(1), one Fe(1), one Fe(2), one Fe(3), one Fe(5), one Fe(6), one Fe(7), one Fe(9), and two equivalent Fe(8) atoms. In the fifth Fe site, Fe(4) is bonded in a body-centered cubic geometry to two equivalent Fe(5), two equivalent Fe(6), and four equivalent Fe(7) atoms. In the sixth Fe site, Fe(5) is bonded in a 13-coordinate geometry to one Er(1), two equivalent Y(1), one Fe(2), one Fe(4), one Fe(5), one Fe(9), two equivalent Fe(3), two equivalent Fe(7), and two equivalent Fe(8) atoms. In the seventh Fe site, Fe(6) is bonded in a 13-coordinate geometry to one Er(1), two equivalent Er(2), one Fe(1), one Fe(4), one Fe(6), one Fe(9), two equivalent Fe(3), two equivalent Fe(7), and two equivalent Fe(8) atoms. In the eighth Fe site, Fe(7) is bonded in a 13-coordinate geometry to one Er(1), one Er(2), one Y(1), one Fe(1), one Fe(10), one Fe(2), one Fe(3), one Fe(4), one Fe(5), one Fe(6), one Fe(7), and two equivalent Fe(8) atoms. In the ninth Fe site, Fe(8) is bonded to one Er(2), two equivalent Er(1), one Y(1), one Fe(1), one Fe(2), one Fe(5), one Fe(6), two equivalent Fe(3), and two equivalent Fe(7) atoms to form FeYEr3Fe8 cuboctahedra that share corners with four equivalent Fe(8)YEr3Fe8 cuboctahedra, faces with two equivalent Fe(10)Y2Er2Fe8 cuboctahedra, faces with two equivalent Fe(9)Y2Er2Fe8 cuboctahedra, and faces with four equivalent Fe(8)YEr3Fe8 cuboctahedra. In the tenth Fe site, Fe(9) is bonded to two equivalent Er(2), two equivalent Y(1), two equivalent Fe(5), two equivalent Fe(6), and four equivalent Fe(3) atoms to form FeY2Er2Fe8 cuboctahedra that share corners with four equivalent Fe(10)Y2Er2Fe8 cuboctahedra and faces with eight equivalent Fe(8)YEr3Fe8 cuboctahedra.
Er4Y2Fe23 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 12-coordinate geometry to one Fe(1), one Fe(2), one Fe(5), one Fe(6), two equivalent Fe(3), two equivalent Fe(7), and four equivalent Fe(8) atoms. The Er(1)-Fe(1) bond length is 3.01 Å. The Er(1)-Fe(2) bond length is 3.00 Å. The Er(1)-Fe(5) bond length is 2.89 Å. The Er(1)-Fe(6) bond length is 2.90 Å. Both Er(1)-Fe(3) bond lengths are 3.00 Å. Both Er(1)-Fe(7) bond lengths are 2.89 Å. All Er(1)-Fe(8) bond lengths are 3.04 Å. In the second Er site, Er(2) is bonded in a 12-coordinate geometry to one Fe(10), one Fe(9), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(6), two equivalent Fe(7), and two equivalent Fe(8) atoms. The Er(2)-Fe(10) bond length is 3.03 Å. The Er(2)-Fe(9) bond length is 3.04 Å. Both Er(2)-Fe(2) bond lengths are 3.00 Å. Both Er(2)-Fe(3) bond lengths are 3.01 Å. Both Er(2)-Fe(6) bond lengths are 2.90 Å. Both Er(2)-Fe(7) bond lengths are 2.89 Å. Both Er(2)-Fe(8) bond lengths are 3.04 Å. Y(1) is bonded in a 12-coordinate geometry to one Fe(10), one Fe(9), two equivalent Fe(1), two equivalent Fe(3), two equivalent Fe(5), two equivalent Fe(7), and two equivalent Fe(8) atoms. The Y(1)-Fe(10) bond length is 3.05 Å. The Y(1)-Fe(9) bond length is 3.04 Å. Both Y(1)-Fe(1) bond lengths are 3.01 Å. Both Y(1)-Fe(3) bond lengths are 3.00 Å. Both Y(1)-Fe(5) bond lengths are 2.91 Å. Both Y(1)-Fe(7) bond lengths are 2.92 Å. Both Y(1)-Fe(8) bond lengths are 3.05 Å. There are ten inequivalent Fe sites. In the first Fe site, Fe(10) is bonded to two equivalent Er(2), two equivalent Y(1), two equivalent Fe(1), two equivalent Fe(2), and four equivalent Fe(7) atoms to form FeY2Er2Fe8 cuboctahedra that share corners with four equivalent Fe(9)Y2Er2Fe8 cuboctahedra and faces with eight equivalent Fe(8)YEr3Fe8 cuboctahedra. Both Fe(10)-Fe(1) bond lengths are 2.47 Å. Both Fe(10)-Fe(2) bond lengths are 2.45 Å. All Fe(10)-Fe(7) bond lengths are 2.63 Å. In the second Fe site, Fe(1) is bonded in a distorted q6 geometry to one Er(1), two equivalent Y(1), one Fe(10), one Fe(2), one Fe(6), two equivalent Fe(3), two equivalent Fe(7), and two equivalent Fe(8) atoms. The Fe(1)-Fe(2) bond length is 2.53 Å. The Fe(1)-Fe(6) bond length is 2.60 Å. Both Fe(1)-Fe(3) bond lengths are 2.52 Å. Both Fe(1)-Fe(7) bond lengths are 2.60 Å. Both Fe(1)-Fe(8) bond lengths are 2.46 Å. In the third Fe site, Fe(2) is bonded in a distorted q6 geometry to one Er(1), two equivalent Er(2), one Fe(1), one Fe(10), one Fe(5), two equivalent Fe(3), two equivalent Fe(7), and two equivalent Fe(8) atoms. The Fe(2)-Fe(5) bond length is 2.60 Å. Both Fe(2)-Fe(3) bond lengths are 2.54 Å. Both Fe(2)-Fe(7) bond lengths are 2.60 Å. Both Fe(2)-Fe(8) bond lengths are 2.45 Å. In the fourth Fe site, Fe(3) is bonded in a distorted q6 geometry to one Er(1), one Er(2), one Y(1), one Fe(1), one Fe(2), one Fe(3), one Fe(5), one Fe(6), one Fe(7), one Fe(9), and two equivalent Fe(8) atoms. The Fe(3)-Fe(3) bond length is 2.53 Å. The Fe(3)-Fe(5) bond length is 2.60 Å. The Fe(3)-Fe(6) bond length is 2.60 Å. The Fe(3)-Fe(7) bond length is 2.60 Å. The Fe(3)-Fe(9) bond length is 2.46 Å. There is one shorter (2.45 Å) and one longer (2.46 Å) Fe(3)-Fe(8) bond length. In the fifth Fe site, Fe(4) is bonded in a body-centered cubic geometry to two equivalent Fe(5), two equivalent Fe(6), and four equivalent Fe(7) atoms. Both Fe(4)-Fe(5) bond lengths are 2.53 Å. Both Fe(4)-Fe(6) bond lengths are 2.52 Å. All Fe(4)-Fe(7) bond lengths are 2.53 Å. In the sixth Fe site, Fe(5) is bonded in a 13-coordinate geometry to one Er(1), two equivalent Y(1), one Fe(2), one Fe(4), one Fe(5), one Fe(9), two equivalent Fe(3), two equivalent Fe(7), and two equivalent Fe(8) atoms. The Fe(5)-Fe(5) bond length is 2.94 Å. The Fe(5)-Fe(9) bond length is 2.64 Å. Both Fe(5)-Fe(7) bond lengths are 2.92 Å. Both Fe(5)-Fe(8) bond lengths are 2.62 Å. In the seventh Fe site, Fe(6) is bonded in a 13-coordinate geometry to one Er(1), two equivalent Er(2), one Fe(1), one Fe(4), one Fe(6), one Fe(9), two equivalent Fe(3), two equivalent Fe(7), and two equivalent Fe(8) atoms. The Fe(6)-Fe(6) bond length is 2.92 Å. The Fe(6)-Fe(9) bond length is 2.62 Å. Both Fe(6)-Fe(7) bond lengths are 2.91 Å. Both Fe(6)-Fe(8) bond lengths are 2.62 Å. In the eighth Fe site, Fe(7) is bonded in a 13-coordinate geometry to one Er(1), one Er(2), one Y(1), one Fe(1), one Fe(10), one Fe(2), one Fe(3), one Fe(4), one Fe(5), one Fe(6), one Fe(7), and two equivalent Fe(8) atoms. The Fe(7)-Fe(7) bond length is 2.93 Å. There is one shorter (2.61 Å) and one longer (2.63 Å) Fe(7)-Fe(8) bond length. In the ninth Fe site, Fe(8) is bonded to one Er(2), two equivalent Er(1), one Y(1), one Fe(1), one Fe(2), one Fe(5), one Fe(6), two equivalent Fe(3), and two equivalent Fe(7) atoms to form FeYEr3Fe8 cuboctahedra that share corners with four equivalent Fe(8)YEr3Fe8 cuboctahedra, faces with two equivalent Fe(10)Y2Er2Fe8 cuboctahedra, faces with two equivalent Fe(9)Y2Er2Fe8 cuboctahedra, and faces with four equivalent Fe(8)YEr3Fe8 cuboctahedra. In the tenth Fe site, Fe(9) is bonded to two equivalent Er(2), two equivalent Y(1), two equivalent Fe(5), two equivalent Fe(6), and four equivalent Fe(3) atoms to form FeY2Er2Fe8 cuboctahedra that share corners with four equivalent Fe(10)Y2Er2Fe8 cuboctahedra and faces with eight equivalent Fe(8)YEr3Fe8 cuboctahedra.