MgDy2Mn4O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 4-coordinate geometry to one O(1), one O(5), one O(6), and one O(8) atom. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded to one O(2), one O(3), one O(4), and one O(7) atom to form distorted DyO4 tetrahedra that share corners with three equivalent Mn(1)O5 square pyramids and corners with three equivalent Mn(3)O5 square pyramids. In the second Dy site, Dy(2) is bonded to one O(1), one O(5), one O(6), and one O(8) atom to form DyO4 tetrahedra that share corners with two equivalent Mn(1)O5 square pyramids and corners with two equivalent Mn(3)O5 square pyramids. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(2), one O(4), one O(7), and one O(8) atom to form distorted MnO5 square pyramids that share corners with two equivalent Dy(2)O4 tetrahedra, corners with three equivalent Dy(1)O4 tetrahedra, and  an edgeedge with one Mn(3)O5 square pyramid. In the second Mn site, Mn(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(7), and one O(8) atom. In the third Mn site, Mn(3) is bonded to one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form distorted MnO5 square pyramids that share corners with two equivalent Dy(2)O4 tetrahedra, corners with three equivalent Dy(1)O4 tetrahedra, and  an edgeedge with one Mn(1)O5 square pyramid. In the fourth Mn site, Mn(4) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and one O(6) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Dy(2), one Mn(1), and one Mn(2) atom to form a mixture of distorted face and corner-sharing ODyMgMn2 tetrahedra. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Dy(1), one Mn(1), one Mn(2), and one Mn(4) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Dy(1), one Mn(2), one Mn(3), and one Mn(4) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Dy(1), one Mn(1), one Mn(3), and one Mn(4) atom. In the fifth O site, O(5) is bonded to one Mg(1), one Dy(2), one Mn(3), and one Mn(4) atom to form a mixture of distorted face and corner-sharing ODyMgMn2 tetrahedra. In the sixth O site, O(6) is bonded to one Mg(1), one Dy(2), one Mn(3), and one Mn(4) atom to form a mixture of distorted face and corner-sharing ODyMgMn2 tetrahedra. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to one Dy(1), one Mn(1), one Mn(2), and one Mn(3) atom. In the eighth O site, O(8) is bonded to one Mg(1), one Dy(2), one Mn(1), and one Mn(2) atom to form a mixture of distorted face and corner-sharing ODyMgMn2 tetrahedra.
MgDy2Mn4O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 4-coordinate geometry to one O(1), one O(5), one O(6), and one O(8) atom. The Mg(1)-O(1) bond length is 2.03 Å. The Mg(1)-O(5) bond length is 1.98 Å. The Mg(1)-O(6) bond length is 2.03 Å. The Mg(1)-O(8) bond length is 1.98 Å. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded to one O(2), one O(3), one O(4), and one O(7) atom to form distorted DyO4 tetrahedra that share corners with three equivalent Mn(1)O5 square pyramids and corners with three equivalent Mn(3)O5 square pyramids. The Dy(1)-O(2) bond length is 2.21 Å. The Dy(1)-O(3) bond length is 2.21 Å. The Dy(1)-O(4) bond length is 2.25 Å. The Dy(1)-O(7) bond length is 2.25 Å. In the second Dy site, Dy(2) is bonded to one O(1), one O(5), one O(6), and one O(8) atom to form DyO4 tetrahedra that share corners with two equivalent Mn(1)O5 square pyramids and corners with two equivalent Mn(3)O5 square pyramids. The Dy(2)-O(1) bond length is 2.24 Å. The Dy(2)-O(5) bond length is 2.18 Å. The Dy(2)-O(6) bond length is 2.24 Å. The Dy(2)-O(8) bond length is 2.18 Å. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(2), one O(4), one O(7), and one O(8) atom to form distorted MnO5 square pyramids that share corners with two equivalent Dy(2)O4 tetrahedra, corners with three equivalent Dy(1)O4 tetrahedra, and  an edgeedge with one Mn(3)O5 square pyramid. The Mn(1)-O(1) bond length is 2.18 Å. The Mn(1)-O(2) bond length is 2.20 Å. The Mn(1)-O(4) bond length is 2.22 Å. The Mn(1)-O(7) bond length is 2.13 Å. The Mn(1)-O(8) bond length is 2.22 Å. In the second Mn site, Mn(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(7), and one O(8) atom. The Mn(2)-O(1) bond length is 2.14 Å. The Mn(2)-O(2) bond length is 2.28 Å. The Mn(2)-O(3) bond length is 2.06 Å. The Mn(2)-O(7) bond length is 2.18 Å. The Mn(2)-O(8) bond length is 2.17 Å. In the third Mn site, Mn(3) is bonded to one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form distorted MnO5 square pyramids that share corners with two equivalent Dy(2)O4 tetrahedra, corners with three equivalent Dy(1)O4 tetrahedra, and  an edgeedge with one Mn(1)O5 square pyramid. The Mn(3)-O(3) bond length is 2.20 Å. The Mn(3)-O(4) bond length is 2.13 Å. The Mn(3)-O(5) bond length is 2.22 Å. The Mn(3)-O(6) bond length is 2.18 Å. The Mn(3)-O(7) bond length is 2.22 Å. In the fourth Mn site, Mn(4) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and one O(6) atom. The Mn(4)-O(2) bond length is 2.06 Å. The Mn(4)-O(3) bond length is 2.28 Å. The Mn(4)-O(4) bond length is 2.17 Å. The Mn(4)-O(5) bond length is 2.17 Å. The Mn(4)-O(6) bond length is 2.15 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Dy(2), one Mn(1), and one Mn(2) atom to form a mixture of distorted face and corner-sharing ODyMgMn2 tetrahedra. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Dy(1), one Mn(1), one Mn(2), and one Mn(4) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Dy(1), one Mn(2), one Mn(3), and one Mn(4) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Dy(1), one Mn(1), one Mn(3), and one Mn(4) atom. In the fifth O site, O(5) is bonded to one Mg(1), one Dy(2), one Mn(3), and one Mn(4) atom to form a mixture of distorted face and corner-sharing ODyMgMn2 tetrahedra. In the sixth O site, O(6) is bonded to one Mg(1), one Dy(2), one Mn(3), and one Mn(4) atom to form a mixture of distorted face and corner-sharing ODyMgMn2 tetrahedra. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to one Dy(1), one Mn(1), one Mn(2), and one Mn(3) atom. In the eighth O site, O(8) is bonded to one Mg(1), one Dy(2), one Mn(1), and one Mn(2) atom to form a mixture of distorted face and corner-sharing ODyMgMn2 tetrahedra.