Mg41Sm5 crystallizes in the tetragonal I4/m space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(7) is bonded in a 12-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), one Mg(5), one Mg(8), two equivalent Mg(6), two equivalent Mg(7), one Sm(1), and two equivalent Sm(2) atoms. In the second Mg site, Mg(1) is bonded in a body-centered cubic geometry to eight equivalent Mg(7) atoms. In the third Mg site, Mg(2) is bonded to two equivalent Mg(4), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), two equivalent Mg(8), and two equivalent Sm(2) atoms to form a mixture of face and corner-sharing MgSm2Mg10 cuboctahedra. In the fourth Mg site, Mg(8) is bonded in a 12-coordinate geometry to one Mg(2), one Mg(4), one Mg(5), one Mg(7), two equivalent Mg(3), two equivalent Mg(6), two equivalent Mg(8), and two equivalent Sm(2) atoms. In the fifth Mg site, Mg(3) is bonded in a 10-coordinate geometry to one Mg(3), one Mg(4), one Mg(5), two equivalent Mg(6), four equivalent Mg(8), and one Sm(2) atom. In the sixth Mg site, Mg(4) is bonded in a 14-coordinate geometry to one Mg(3), one Mg(5), two equivalent Mg(2), two equivalent Mg(7), two equivalent Mg(8), four equivalent Mg(6), one Sm(1), and one Sm(2) atom. In the seventh Mg site, Mg(5) is bonded to one Mg(3), one Mg(4), two equivalent Mg(2), two equivalent Mg(6), two equivalent Mg(7), two equivalent Mg(8), and two equivalent Sm(2) atoms to form a mixture of distorted face and corner-sharing MgSm2Mg10 cuboctahedra. In the eighth Mg site, Mg(6) is bonded in a 12-coordinate geometry to one Mg(2), one Mg(3), one Mg(5), one Mg(6), two equivalent Mg(4), two equivalent Mg(7), two equivalent Mg(8), one Sm(1), and one Sm(2) atom. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 20-coordinate geometry to four equivalent Mg(4), eight equivalent Mg(6), and eight equivalent Mg(7) atoms. In the second Sm site, Sm(2) is bonded in a 16-coordinate geometry to one Mg(3), one Mg(4), two equivalent Mg(2), two equivalent Mg(5), two equivalent Mg(6), four equivalent Mg(7), and four equivalent Mg(8) atoms.
Mg41Sm5 crystallizes in the tetragonal I4/m space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(7) is bonded in a 12-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), one Mg(5), one Mg(8), two equivalent Mg(6), two equivalent Mg(7), one Sm(1), and two equivalent Sm(2) atoms. The Mg(7)-Mg(1) bond length is 3.02 Å. The Mg(7)-Mg(2) bond length is 3.10 Å. The Mg(7)-Mg(4) bond length is 3.51 Å. The Mg(7)-Mg(5) bond length is 3.15 Å. The Mg(7)-Mg(8) bond length is 3.42 Å. There is one shorter (2.95 Å) and one longer (2.98 Å) Mg(7)-Mg(6) bond length. Both Mg(7)-Mg(7) bond lengths are 3.24 Å. The Mg(7)-Sm(1) bond length is 3.95 Å. There is one shorter (3.48 Å) and one longer (3.50 Å) Mg(7)-Sm(2) bond length. In the second Mg site, Mg(1) is bonded in a body-centered cubic geometry to eight equivalent Mg(7) atoms. In the third Mg site, Mg(2) is bonded to two equivalent Mg(4), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), two equivalent Mg(8), and two equivalent Sm(2) atoms to form a mixture of face and corner-sharing MgSm2Mg10 cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.22 Å. Both Mg(2)-Mg(5) bond lengths are 2.95 Å. Both Mg(2)-Mg(6) bond lengths are 2.99 Å. Both Mg(2)-Mg(8) bond lengths are 3.06 Å. Both Mg(2)-Sm(2) bond lengths are 3.69 Å. In the fourth Mg site, Mg(8) is bonded in a 12-coordinate geometry to one Mg(2), one Mg(4), one Mg(5), one Mg(7), two equivalent Mg(3), two equivalent Mg(6), two equivalent Mg(8), and two equivalent Sm(2) atoms. The Mg(8)-Mg(4) bond length is 3.48 Å. The Mg(8)-Mg(5) bond length is 3.03 Å. There is one shorter (3.01 Å) and one longer (3.10 Å) Mg(8)-Mg(3) bond length. There is one shorter (3.10 Å) and one longer (3.22 Å) Mg(8)-Mg(6) bond length. Both Mg(8)-Mg(8) bond lengths are 3.20 Å. There is one shorter (3.64 Å) and one longer (3.67 Å) Mg(8)-Sm(2) bond length. In the fifth Mg site, Mg(3) is bonded in a 10-coordinate geometry to one Mg(3), one Mg(4), one Mg(5), two equivalent Mg(6), four equivalent Mg(8), and one Sm(2) atom. The Mg(3)-Mg(3) bond length is 2.87 Å. The Mg(3)-Mg(4) bond length is 3.28 Å. The Mg(3)-Mg(5) bond length is 3.18 Å. Both Mg(3)-Mg(6) bond lengths are 3.09 Å. The Mg(3)-Sm(2) bond length is 3.62 Å. In the sixth Mg site, Mg(4) is bonded in a 14-coordinate geometry to one Mg(3), one Mg(5), two equivalent Mg(2), two equivalent Mg(7), two equivalent Mg(8), four equivalent Mg(6), one Sm(1), and one Sm(2) atom. The Mg(4)-Mg(5) bond length is 3.22 Å. There are two shorter (3.09 Å) and two longer (3.20 Å) Mg(4)-Mg(6) bond lengths. The Mg(4)-Sm(1) bond length is 3.72 Å. The Mg(4)-Sm(2) bond length is 3.46 Å. In the seventh Mg site, Mg(5) is bonded to one Mg(3), one Mg(4), two equivalent Mg(2), two equivalent Mg(6), two equivalent Mg(7), two equivalent Mg(8), and two equivalent Sm(2) atoms to form a mixture of distorted face and corner-sharing MgSm2Mg10 cuboctahedra. Both Mg(5)-Mg(6) bond lengths are 3.23 Å. There is one shorter (3.39 Å) and one longer (3.46 Å) Mg(5)-Sm(2) bond length. In the eighth Mg site, Mg(6) is bonded in a 12-coordinate geometry to one Mg(2), one Mg(3), one Mg(5), one Mg(6), two equivalent Mg(4), two equivalent Mg(7), two equivalent Mg(8), one Sm(1), and one Sm(2) atom. The Mg(6)-Mg(6) bond length is 3.05 Å. The Mg(6)-Sm(1) bond length is 3.77 Å. The Mg(6)-Sm(2) bond length is 3.69 Å. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 20-coordinate geometry to four equivalent Mg(4), eight equivalent Mg(6), and eight equivalent Mg(7) atoms. In the second Sm site, Sm(2) is bonded in a 16-coordinate geometry to one Mg(3), one Mg(4), two equivalent Mg(2), two equivalent Mg(5), two equivalent Mg(6), four equivalent Mg(7), and four equivalent Mg(8) atoms.