Mg5Mn3 crystallizes in the triclinic P-1 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Mg(3), one Mg(4), one Mg(5), two equivalent Mg(1), three equivalent Mn(1), and four equivalent Mn(2) atoms to form distorted MgMg5Mn7 cuboctahedra that share corners with two equivalent Mg(1)Mg5Mn7 cuboctahedra, corners with two equivalent Mg(3)Mg6Mn6 cuboctahedra, corners with two equivalent Mg(4)Mg8Mn4 cuboctahedra, corners with two equivalent Mn(1)Mg10Mn2 cuboctahedra, corners with four equivalent Mn(3)Mg9Mn3 cuboctahedra,  an edgeedge with one Mg(4)Mg8Mn4 cuboctahedra,  an edgeedge with one Mn(1)Mg10Mn2 cuboctahedra, edges with two equivalent Mg(1)Mg5Mn7 cuboctahedra, edges with two equivalent Mn(3)Mg9Mn3 cuboctahedra, edges with four equivalent Mg(2)Mg7Mn5 cuboctahedra, edges with five equivalent Mg(3)Mg6Mn6 cuboctahedra,  a faceface with one Mg(3)Mg6Mn6 cuboctahedra, faces with three equivalent Mg(4)Mg8Mn4 cuboctahedra, faces with three equivalent Mn(1)Mg10Mn2 cuboctahedra, and faces with four equivalent Mg(1)Mg5Mn7 cuboctahedra. In the second Mg site, Mg(2) is bonded to one Mg(3), one Mg(5), two equivalent Mg(2), three equivalent Mg(4), one Mn(1), and four equivalent Mn(3) atoms to form distorted MgMg7Mn5 cuboctahedra that share corners with two equivalent Mg(3)Mg6Mn6 cuboctahedra, corners with two equivalent Mg(2)Mg7Mn5 cuboctahedra, corners with two equivalent Mg(4)Mg8Mn4 cuboctahedra, corners with two equivalent Mn(1)Mg10Mn2 cuboctahedra, corners with four equivalent Mn(3)Mg9Mn3 cuboctahedra,  an edgeedge with one Mg(3)Mg6Mn6 cuboctahedra,  an edgeedge with one Mg(4)Mg8Mn4 cuboctahedra,  an edgeedge with one Mn(1)Mg10Mn2 cuboctahedra, edges with two equivalent Mg(2)Mg7Mn5 cuboctahedra, edges with two equivalent Mn(3)Mg9Mn3 cuboctahedra, edges with four equivalent Mg(1)Mg5Mn7 cuboctahedra, faces with three equivalent Mg(4)Mg8Mn4 cuboctahedra, faces with three equivalent Mn(1)Mg10Mn2 cuboctahedra, faces with four equivalent Mg(2)Mg7Mn5 cuboctahedra, faces with four equivalent Mn(3)Mg9Mn3 cuboctahedra, and faces with five equivalent Mg(3)Mg6Mn6 cuboctahedra. In the third Mg site, Mg(3) is bonded to one Mg(1), one Mg(2), two equivalent Mg(4), two equivalent Mg(5), one Mn(2), two equivalent Mn(1), and three equivalent Mn(3) atoms to form distorted MgMg6Mn6 cuboctahedra that share corners with two equivalent Mg(1)Mg5Mn7 cuboctahedra, corners with two equivalent Mg(3)Mg6Mn6 cuboctahedra, corners with two equivalent Mg(2)Mg7Mn5 cuboctahedra, corners with two equivalent Mn(3)Mg9Mn3 cuboctahedra, corners with four equivalent Mg(4)Mg8Mn4 cuboctahedra, corners with four equivalent Mn(1)Mg10Mn2 cuboctahedra,  an edgeedge with one Mg(2)Mg7Mn5 cuboctahedra,  an edgeedge with one Mn(3)Mg9Mn3 cuboctahedra, edges with two equivalent Mg(3)Mg6Mn6 cuboctahedra, edges with two equivalent Mg(4)Mg8Mn4 cuboctahedra, edges with two equivalent Mn(1)Mg10Mn2 cuboctahedra, edges with five equivalent Mg(1)Mg5Mn7 cuboctahedra,  a faceface with one Mg(1)Mg5Mn7 cuboctahedra, faces with two equivalent Mg(3)Mg6Mn6 cuboctahedra, faces with two equivalent Mg(4)Mg8Mn4 cuboctahedra, faces with two equivalent Mn(1)Mg10Mn2 cuboctahedra, faces with three equivalent Mn(3)Mg9Mn3 cuboctahedra, and faces with five equivalent Mg(2)Mg7Mn5 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to one Mg(1), two equivalent Mg(3), two equivalent Mg(5), three equivalent Mg(2), one Mn(2), one Mn(3), and two equivalent Mn(1) atoms to form distorted MgMg8Mn4 cuboctahedra that share corners with two equivalent Mg(1)Mg5Mn7 cuboctahedra, corners with two equivalent Mg(2)Mg7Mn5 cuboctahedra, corners with two equivalent Mg(4)Mg8Mn4 cuboctahedra, corners with two equivalent Mn(3)Mg9Mn3 cuboctahedra, corners with four equivalent Mg(3)Mg6Mn6 cuboctahedra,  an edgeedge with one Mg(1)Mg5Mn7 cuboctahedra,  an edgeedge with one Mg(2)Mg7Mn5 cuboctahedra,  an edgeedge with one Mn(3)Mg9Mn3 cuboctahedra, edges with two equivalent Mg(3)Mg6Mn6 cuboctahedra, edges with two equivalent Mg(4)Mg8Mn4 cuboctahedra, edges with four equivalent Mn(1)Mg10Mn2 cuboctahedra, faces with two equivalent Mg(3)Mg6Mn6 cuboctahedra, faces with two equivalent Mg(4)Mg8Mn4 cuboctahedra, faces with two equivalent Mn(1)Mg10Mn2 cuboctahedra, faces with three equivalent Mg(1)Mg5Mn7 cuboctahedra, faces with three equivalent Mg(2)Mg7Mn5 cuboctahedra, and faces with five equivalent Mn(3)Mg9Mn3 cuboctahedra. In the fifth Mg site, Mg(5) is bonded in a 12-coordinate geometry to one Mg(1), one Mg(2), two equivalent Mg(3), two equivalent Mg(4), one Mn(3), two equivalent Mn(1), and three equivalent Mn(2) atoms. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(5), three equivalent Mg(1), one Mn(2), and one Mn(3) atom to form distorted MnMg10Mn2 cuboctahedra that share corners with two equivalent Mg(1)Mg5Mn7 cuboctahedra, corners with two equivalent Mg(2)Mg7Mn5 cuboctahedra, corners with two equivalent Mn(1)Mg10Mn2 cuboctahedra, corners with two equivalent Mn(3)Mg9Mn3 cuboctahedra, corners with four equivalent Mg(3)Mg6Mn6 cuboctahedra,  an edgeedge with one Mg(1)Mg5Mn7 cuboctahedra,  an edgeedge with one Mg(2)Mg7Mn5 cuboctahedra, edges with two equivalent Mg(3)Mg6Mn6 cuboctahedra, edges with two equivalent Mn(1)Mg10Mn2 cuboctahedra, edges with four equivalent Mg(4)Mg8Mn4 cuboctahedra, edges with five equivalent Mn(3)Mg9Mn3 cuboctahedra,  a faceface with one Mn(3)Mg9Mn3 cuboctahedra, faces with two equivalent Mg(3)Mg6Mn6 cuboctahedra, faces with two equivalent Mg(4)Mg8Mn4 cuboctahedra, faces with two equivalent Mn(1)Mg10Mn2 cuboctahedra, faces with three equivalent Mg(1)Mg5Mn7 cuboctahedra, and faces with three equivalent Mg(2)Mg7Mn5 cuboctahedra. In the second Mn site, Mn(2) is bonded in a 12-coordinate geometry to one Mg(3), one Mg(4), three equivalent Mg(5), four equivalent Mg(1), one Mn(1), and two equivalent Mn(2) atoms. In the third Mn site, Mn(3) is bonded to one Mg(4), one Mg(5), three equivalent Mg(3), four equivalent Mg(2), one Mn(1), and two equivalent Mn(3) atoms to form distorted MnMg9Mn3 cuboctahedra that share corners with two equivalent Mg(3)Mg6Mn6 cuboctahedra, corners with two equivalent Mg(4)Mg8Mn4 cuboctahedra, corners with two equivalent Mn(1)Mg10Mn2 cuboctahedra, corners with two equivalent Mn(3)Mg9Mn3 cuboctahedra, corners with four equivalent Mg(1)Mg5Mn7 cuboctahedra, corners with four equivalent Mg(2)Mg7Mn5 cuboctahedra,  an edgeedge with one Mg(3)Mg6Mn6 cuboctahedra,  an edgeedge with one Mg(4)Mg8Mn4 cuboctahedra, edges with two equivalent Mg(1)Mg5Mn7 cuboctahedra, edges with two equivalent Mg(2)Mg7Mn5 cuboctahedra, edges with two equivalent Mn(3)Mg9Mn3 cuboctahedra, edges with five equivalent Mn(1)Mg10Mn2 cuboctahedra,  a faceface with one Mn(1)Mg10Mn2 cuboctahedra, faces with three equivalent Mg(3)Mg6Mn6 cuboctahedra, faces with four equivalent Mg(2)Mg7Mn5 cuboctahedra, faces with four equivalent Mn(3)Mg9Mn3 cuboctahedra, and faces with five equivalent Mg(4)Mg8Mn4 cuboctahedra.
Mg5Mn3 crystallizes in the triclinic P-1 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Mg(3), one Mg(4), one Mg(5), two equivalent Mg(1), three equivalent Mn(1), and four equivalent Mn(2) atoms to form distorted MgMg5Mn7 cuboctahedra that share corners with two equivalent Mg(1)Mg5Mn7 cuboctahedra, corners with two equivalent Mg(3)Mg6Mn6 cuboctahedra, corners with two equivalent Mg(4)Mg8Mn4 cuboctahedra, corners with two equivalent Mn(1)Mg10Mn2 cuboctahedra, corners with four equivalent Mn(3)Mg9Mn3 cuboctahedra,  an edgeedge with one Mg(4)Mg8Mn4 cuboctahedra,  an edgeedge with one Mn(1)Mg10Mn2 cuboctahedra, edges with two equivalent Mg(1)Mg5Mn7 cuboctahedra, edges with two equivalent Mn(3)Mg9Mn3 cuboctahedra, edges with four equivalent Mg(2)Mg7Mn5 cuboctahedra, edges with five equivalent Mg(3)Mg6Mn6 cuboctahedra,  a faceface with one Mg(3)Mg6Mn6 cuboctahedra, faces with three equivalent Mg(4)Mg8Mn4 cuboctahedra, faces with three equivalent Mn(1)Mg10Mn2 cuboctahedra, and faces with four equivalent Mg(1)Mg5Mn7 cuboctahedra. The Mg(1)-Mg(3) bond length is 3.05 Å. The Mg(1)-Mg(4) bond length is 3.07 Å. The Mg(1)-Mg(5) bond length is 3.00 Å. There is one shorter (3.03 Å) and one longer (3.09 Å) Mg(1)-Mg(1) bond length. There are a spread of Mg(1)-Mn(1) bond distances ranging from 2.91-3.03 Å. There are a spread of Mg(1)-Mn(2) bond distances ranging from 2.89-2.99 Å. In the second Mg site, Mg(2) is bonded to one Mg(3), one Mg(5), two equivalent Mg(2), three equivalent Mg(4), one Mn(1), and four equivalent Mn(3) atoms to form distorted MgMg7Mn5 cuboctahedra that share corners with two equivalent Mg(3)Mg6Mn6 cuboctahedra, corners with two equivalent Mg(2)Mg7Mn5 cuboctahedra, corners with two equivalent Mg(4)Mg8Mn4 cuboctahedra, corners with two equivalent Mn(1)Mg10Mn2 cuboctahedra, corners with four equivalent Mn(3)Mg9Mn3 cuboctahedra,  an edgeedge with one Mg(3)Mg6Mn6 cuboctahedra,  an edgeedge with one Mg(4)Mg8Mn4 cuboctahedra,  an edgeedge with one Mn(1)Mg10Mn2 cuboctahedra, edges with two equivalent Mg(2)Mg7Mn5 cuboctahedra, edges with two equivalent Mn(3)Mg9Mn3 cuboctahedra, edges with four equivalent Mg(1)Mg5Mn7 cuboctahedra, faces with three equivalent Mg(4)Mg8Mn4 cuboctahedra, faces with three equivalent Mn(1)Mg10Mn2 cuboctahedra, faces with four equivalent Mg(2)Mg7Mn5 cuboctahedra, faces with four equivalent Mn(3)Mg9Mn3 cuboctahedra, and faces with five equivalent Mg(3)Mg6Mn6 cuboctahedra. The Mg(2)-Mg(3) bond length is 3.00 Å. The Mg(2)-Mg(5) bond length is 3.10 Å. There is one shorter (3.06 Å) and one longer (3.13 Å) Mg(2)-Mg(2) bond length. There are two shorter (2.98 Å) and one longer (3.12 Å) Mg(2)-Mg(4) bond length. The Mg(2)-Mn(1) bond length is 3.07 Å. There are a spread of Mg(2)-Mn(3) bond distances ranging from 2.90-2.99 Å. In the third Mg site, Mg(3) is bonded to one Mg(1), one Mg(2), two equivalent Mg(4), two equivalent Mg(5), one Mn(2), two equivalent Mn(1), and three equivalent Mn(3) atoms to form distorted MgMg6Mn6 cuboctahedra that share corners with two equivalent Mg(1)Mg5Mn7 cuboctahedra, corners with two equivalent Mg(3)Mg6Mn6 cuboctahedra, corners with two equivalent Mg(2)Mg7Mn5 cuboctahedra, corners with two equivalent Mn(3)Mg9Mn3 cuboctahedra, corners with four equivalent Mg(4)Mg8Mn4 cuboctahedra, corners with four equivalent Mn(1)Mg10Mn2 cuboctahedra,  an edgeedge with one Mg(2)Mg7Mn5 cuboctahedra,  an edgeedge with one Mn(3)Mg9Mn3 cuboctahedra, edges with two equivalent Mg(3)Mg6Mn6 cuboctahedra, edges with two equivalent Mg(4)Mg8Mn4 cuboctahedra, edges with two equivalent Mn(1)Mg10Mn2 cuboctahedra, edges with five equivalent Mg(1)Mg5Mn7 cuboctahedra,  a faceface with one Mg(1)Mg5Mn7 cuboctahedra, faces with two equivalent Mg(3)Mg6Mn6 cuboctahedra, faces with two equivalent Mg(4)Mg8Mn4 cuboctahedra, faces with two equivalent Mn(1)Mg10Mn2 cuboctahedra, faces with three equivalent Mn(3)Mg9Mn3 cuboctahedra, and faces with five equivalent Mg(2)Mg7Mn5 cuboctahedra. There is one shorter (2.96 Å) and one longer (2.99 Å) Mg(3)-Mg(4) bond length. There is one shorter (2.94 Å) and one longer (2.98 Å) Mg(3)-Mg(5) bond length. The Mg(3)-Mn(2) bond length is 3.21 Å. There is one shorter (2.95 Å) and one longer (3.13 Å) Mg(3)-Mn(1) bond length. There are a spread of Mg(3)-Mn(3) bond distances ranging from 2.85-2.99 Å. In the fourth Mg site, Mg(4) is bonded to one Mg(1), two equivalent Mg(3), two equivalent Mg(5), three equivalent Mg(2), one Mn(2), one Mn(3), and two equivalent Mn(1) atoms to form distorted MgMg8Mn4 cuboctahedra that share corners with two equivalent Mg(1)Mg5Mn7 cuboctahedra, corners with two equivalent Mg(2)Mg7Mn5 cuboctahedra, corners with two equivalent Mg(4)Mg8Mn4 cuboctahedra, corners with two equivalent Mn(3)Mg9Mn3 cuboctahedra, corners with four equivalent Mg(3)Mg6Mn6 cuboctahedra,  an edgeedge with one Mg(1)Mg5Mn7 cuboctahedra,  an edgeedge with one Mg(2)Mg7Mn5 cuboctahedra,  an edgeedge with one Mn(3)Mg9Mn3 cuboctahedra, edges with two equivalent Mg(3)Mg6Mn6 cuboctahedra, edges with two equivalent Mg(4)Mg8Mn4 cuboctahedra, edges with four equivalent Mn(1)Mg10Mn2 cuboctahedra, faces with two equivalent Mg(3)Mg6Mn6 cuboctahedra, faces with two equivalent Mg(4)Mg8Mn4 cuboctahedra, faces with two equivalent Mn(1)Mg10Mn2 cuboctahedra, faces with three equivalent Mg(1)Mg5Mn7 cuboctahedra, faces with three equivalent Mg(2)Mg7Mn5 cuboctahedra, and faces with five equivalent Mn(3)Mg9Mn3 cuboctahedra. There is one shorter (3.09 Å) and one longer (3.13 Å) Mg(4)-Mg(5) bond length. The Mg(4)-Mn(2) bond length is 2.91 Å. The Mg(4)-Mn(3) bond length is 3.18 Å. There is one shorter (2.91 Å) and one longer (2.95 Å) Mg(4)-Mn(1) bond length. In the fifth Mg site, Mg(5) is bonded in a 12-coordinate geometry to one Mg(1), one Mg(2), two equivalent Mg(3), two equivalent Mg(4), one Mn(3), two equivalent Mn(1), and three equivalent Mn(2) atoms. The Mg(5)-Mn(3) bond length is 3.07 Å. There is one shorter (2.82 Å) and one longer (3.12 Å) Mg(5)-Mn(1) bond length. There are a spread of Mg(5)-Mn(2) bond distances ranging from 2.79-2.97 Å. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(5), three equivalent Mg(1), one Mn(2), and one Mn(3) atom to form distorted MnMg10Mn2 cuboctahedra that share corners with two equivalent Mg(1)Mg5Mn7 cuboctahedra, corners with two equivalent Mg(2)Mg7Mn5 cuboctahedra, corners with two equivalent Mn(1)Mg10Mn2 cuboctahedra, corners with two equivalent Mn(3)Mg9Mn3 cuboctahedra, corners with four equivalent Mg(3)Mg6Mn6 cuboctahedra,  an edgeedge with one Mg(1)Mg5Mn7 cuboctahedra,  an edgeedge with one Mg(2)Mg7Mn5 cuboctahedra, edges with two equivalent Mg(3)Mg6Mn6 cuboctahedra, edges with two equivalent Mn(1)Mg10Mn2 cuboctahedra, edges with four equivalent Mg(4)Mg8Mn4 cuboctahedra, edges with five equivalent Mn(3)Mg9Mn3 cuboctahedra,  a faceface with one Mn(3)Mg9Mn3 cuboctahedra, faces with two equivalent Mg(3)Mg6Mn6 cuboctahedra, faces with two equivalent Mg(4)Mg8Mn4 cuboctahedra, faces with two equivalent Mn(1)Mg10Mn2 cuboctahedra, faces with three equivalent Mg(1)Mg5Mn7 cuboctahedra, and faces with three equivalent Mg(2)Mg7Mn5 cuboctahedra. The Mn(1)-Mn(2) bond length is 3.03 Å. The Mn(1)-Mn(3) bond length is 2.93 Å. In the second Mn site, Mn(2) is bonded in a 12-coordinate geometry to one Mg(3), one Mg(4), three equivalent Mg(5), four equivalent Mg(1), one Mn(1), and two equivalent Mn(2) atoms. There is one shorter (2.90 Å) and one longer (3.16 Å) Mn(2)-Mn(2) bond length. In the third Mn site, Mn(3) is bonded to one Mg(4), one Mg(5), three equivalent Mg(3), four equivalent Mg(2), one Mn(1), and two equivalent Mn(3) atoms to form distorted MnMg9Mn3 cuboctahedra that share corners with two equivalent Mg(3)Mg6Mn6 cuboctahedra, corners with two equivalent Mg(4)Mg8Mn4 cuboctahedra, corners with two equivalent Mn(1)Mg10Mn2 cuboctahedra, corners with two equivalent Mn(3)Mg9Mn3 cuboctahedra, corners with four equivalent Mg(1)Mg5Mn7 cuboctahedra, corners with four equivalent Mg(2)Mg7Mn5 cuboctahedra,  an edgeedge with one Mg(3)Mg6Mn6 cuboctahedra,  an edgeedge with one Mg(4)Mg8Mn4 cuboctahedra, edges with two equivalent Mg(1)Mg5Mn7 cuboctahedra, edges with two equivalent Mg(2)Mg7Mn5 cuboctahedra, edges with two equivalent Mn(3)Mg9Mn3 cuboctahedra, edges with five equivalent Mn(1)Mg10Mn2 cuboctahedra,  a faceface with one Mn(1)Mg10Mn2 cuboctahedra, faces with three equivalent Mg(3)Mg6Mn6 cuboctahedra, faces with four equivalent Mg(2)Mg7Mn5 cuboctahedra, faces with four equivalent Mn(3)Mg9Mn3 cuboctahedra, and faces with five equivalent Mg(4)Mg8Mn4 cuboctahedra. There is one shorter (3.07 Å) and one longer (3.12 Å) Mn(3)-Mn(3) bond length.