Mg6MnCu crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mn(1), and two equivalent Cu(1) atoms to form distorted MgMg8Mn2Cu2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Mn2 cuboctahedra; corners with four equivalent Mn(1)Mg10Cu2 cuboctahedra; corners with ten Mg(1,1)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with two equivalent Mg(1)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mn(1)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(3)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; and faces with eight Mg(3,3)Mg8Mn2Cu2 cuboctahedra. In the second Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mn(1), and two equivalent Cu(1) atoms to form distorted MgMg8Mn2Cu2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Mn2 cuboctahedra; corners with four equivalent Mn(1)Mg10Cu2 cuboctahedra; corners with ten Mg(1,1)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with two equivalent Mg(1)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mn(1)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(3)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; and faces with eight Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra. In the third Mg site, Mg(2) is bonded to two equivalent Mg(4); four Mg(1,1); four Mg(3,3); and two equivalent Mn(1) atoms to form MgMg10Mn2 cuboctahedra that share corners with four equivalent Mn(1)Mg10Cu2 cuboctahedra; corners with six equivalent Mg(2)Mg10Mn2 cuboctahedra; corners with eight Mg(1,1)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mn(1)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; edges with eight Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; faces with four Mg(3,3)Mg8Mn2Cu2 cuboctahedra; and faces with six equivalent Cu(1)Mg10Mn2 cuboctahedra. In the fourth Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mn(1), and two equivalent Cu(1) atoms to form distorted MgMg8Mn2Cu2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cu2 cuboctahedra; corners with four equivalent Cu(1)Mg10Mn2 cuboctahedra; corners with ten Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with two equivalent Mg(3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Cu(1)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(1)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(3,3)Mg8Mn2Cu2 cuboctahedra; and faces with eight Mg(1,1)Mg8Mn2Cu2 cuboctahedra. In the fifth Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mn(1), and two equivalent Cu(1) atoms to form distorted MgMg8Mn2Cu2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cu2 cuboctahedra; corners with four equivalent Cu(1)Mg10Mn2 cuboctahedra; corners with ten Mg(3,3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with two equivalent Mg(3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Cu(1)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(1)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(3,3)Mg8Mn2Cu2 cuboctahedra; and faces with eight equivalent Mg(1)Mg8Mn2Cu2 cuboctahedra. In the sixth Mg site, Mg(4) is bonded to two equivalent Mg(2); four Mg(1,1); four Mg(3,3,3); and two equivalent Cu(1) atoms to form distorted MgMg10Cu2 cuboctahedra that share corners with four equivalent Cu(1)Mg10Mn2 cuboctahedra; corners with six equivalent Mg(4)Mg10Cu2 cuboctahedra; corners with eight Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Cu(1)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with four Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; edges with eight Mg(1,1)Mg8Mn2Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; faces with four Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; and faces with six equivalent Mn(1)Mg10Cu2 cuboctahedra. In the seventh Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mn(1), and two equivalent Cu(1) atoms to form distorted MgMg8Mn2Cu2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cu2 cuboctahedra; corners with four equivalent Cu(1)Mg10Mn2 cuboctahedra; corners with ten Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with two equivalent Mg(3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Cu(1)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(1)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(3,3)Mg8Mn2Cu2 cuboctahedra; and faces with eight Mg(1,1)Mg8Mn2Cu2 cuboctahedra. Mn(1) is bonded to two equivalent Mg(2); four Mg(1,1); four Mg(3,3); and two equivalent Cu(1) atoms to form MnMg10Cu2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Mn2 cuboctahedra; corners with six equivalent Mn(1)Mg10Cu2 cuboctahedra; corners with eight Mg(1,1)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Cu(1)Mg10Mn2 cuboctahedra; edges with eight Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; faces with four Mg(3,3)Mg8Mn2Cu2 cuboctahedra; and faces with six equivalent Mg(4)Mg10Cu2 cuboctahedra. Cu(1) is bonded to two equivalent Mg(4); four Mg(1,1); four Mg(3,3,3); and two equivalent Mn(1) atoms to form CuMg10Mn2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cu2 cuboctahedra; corners with six equivalent Cu(1)Mg10Mn2 cuboctahedra; corners with eight Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with four Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Mn(1)Mg10Cu2 cuboctahedra; edges with eight Mg(1,1)Mg8Mn2Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; faces with four Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; and faces with six equivalent Mg(2)Mg10Mn2 cuboctahedra.
Mg6MnCu crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mn(1), and two equivalent Cu(1) atoms to form distorted MgMg8Mn2Cu2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Mn2 cuboctahedra; corners with four equivalent Mn(1)Mg10Cu2 cuboctahedra; corners with ten Mg(1,1)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with two equivalent Mg(1)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mn(1)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(3)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; and faces with eight Mg(3,3)Mg8Mn2Cu2 cuboctahedra. There is one shorter (2.91 Å) and one longer (3.17 Å) Mg(1)-Mg(1) bond length. There is one shorter (3.04 Å) and one longer (3.05 Å) Mg(1)-Mg(2) bond length. Both Mg(1)-Mg(3) bond lengths are 3.06 Å. Both Mg(1)-Mg(4) bond lengths are 3.02 Å. There is one shorter (2.91 Å) and one longer (3.17 Å) Mg(1)-Mn(1) bond length. Both Mg(1)-Cu(1) bond lengths are 2.97 Å. In the second Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mn(1), and two equivalent Cu(1) atoms to form distorted MgMg8Mn2Cu2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Mn2 cuboctahedra; corners with four equivalent Mn(1)Mg10Cu2 cuboctahedra; corners with ten Mg(1,1)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with two equivalent Mg(1)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mn(1)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(3)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; and faces with eight Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra. There is one shorter (3.04 Å) and one longer (3.05 Å) Mg(1)-Mg(2) bond length. Both Mg(1)-Mg(3) bond lengths are 3.06 Å. Both Mg(1)-Mg(4) bond lengths are 3.02 Å. There is one shorter (2.91 Å) and one longer (3.17 Å) Mg(1)-Mn(1) bond length. Both Mg(1)-Cu(1) bond lengths are 2.97 Å. In the third Mg site, Mg(2) is bonded to two equivalent Mg(4); four Mg(1,1); four Mg(3,3); and two equivalent Mn(1) atoms to form MgMg10Mn2 cuboctahedra that share corners with four equivalent Mn(1)Mg10Cu2 cuboctahedra; corners with six equivalent Mg(2)Mg10Mn2 cuboctahedra; corners with eight Mg(1,1)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mn(1)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; edges with eight Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; faces with four Mg(3,3)Mg8Mn2Cu2 cuboctahedra; and faces with six equivalent Cu(1)Mg10Mn2 cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.00 Å. All Mg(2)-Mg(3,3) bond lengths are 3.00 Å. Both Mg(2)-Mn(1) bond lengths are 3.04 Å. In the fourth Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mn(1), and two equivalent Cu(1) atoms to form distorted MgMg8Mn2Cu2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cu2 cuboctahedra; corners with four equivalent Cu(1)Mg10Mn2 cuboctahedra; corners with ten Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with two equivalent Mg(3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Cu(1)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(1)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(3,3)Mg8Mn2Cu2 cuboctahedra; and faces with eight Mg(1,1)Mg8Mn2Cu2 cuboctahedra. Both Mg(3)-Mg(1) bond lengths are 3.06 Å. There is one shorter (2.94 Å) and one longer (3.14 Å) Mg(3)-Mg(3) bond length. There is one shorter (3.02 Å) and one longer (3.06 Å) Mg(3)-Mg(4) bond length. Both Mg(3)-Mn(1) bond lengths are 2.97 Å. There is one shorter (2.90 Å) and one longer (3.18 Å) Mg(3)-Cu(1) bond length. In the fifth Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mn(1), and two equivalent Cu(1) atoms to form distorted MgMg8Mn2Cu2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cu2 cuboctahedra; corners with four equivalent Cu(1)Mg10Mn2 cuboctahedra; corners with ten Mg(3,3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with two equivalent Mg(3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Cu(1)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(1)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(3,3)Mg8Mn2Cu2 cuboctahedra; and faces with eight equivalent Mg(1)Mg8Mn2Cu2 cuboctahedra. Both Mg(3)-Mg(1) bond lengths are 3.06 Å. There is one shorter (3.02 Å) and one longer (3.06 Å) Mg(3)-Mg(4) bond length. Both Mg(3)-Mn(1) bond lengths are 2.97 Å. There is one shorter (2.90 Å) and one longer (3.18 Å) Mg(3)-Cu(1) bond length. In the sixth Mg site, Mg(4) is bonded to two equivalent Mg(2); four Mg(1,1); four Mg(3,3,3); and two equivalent Cu(1) atoms to form distorted MgMg10Cu2 cuboctahedra that share corners with four equivalent Cu(1)Mg10Mn2 cuboctahedra; corners with six equivalent Mg(4)Mg10Cu2 cuboctahedra; corners with eight Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Cu(1)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with four Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; edges with eight Mg(1,1)Mg8Mn2Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; faces with four Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; and faces with six equivalent Mn(1)Mg10Cu2 cuboctahedra. The Mg(4)-Mg(3) bond length is 3.06 Å. Both Mg(4)-Cu(1) bond lengths are 3.04 Å. In the seventh Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mn(1), and two equivalent Cu(1) atoms to form distorted MgMg8Mn2Cu2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cu2 cuboctahedra; corners with four equivalent Cu(1)Mg10Mn2 cuboctahedra; corners with ten Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with two equivalent Mg(3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Cu(1)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with four equivalent Mg(1)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(3,3)Mg8Mn2Cu2 cuboctahedra; and faces with eight Mg(1,1)Mg8Mn2Cu2 cuboctahedra. Both Mg(3)-Mg(2) bond lengths are 3.00 Å. There is one shorter (2.94 Å) and one longer (3.14 Å) Mg(3)-Mg(3) bond length. Both Mg(3)-Mn(1) bond lengths are 2.97 Å. There is one shorter (2.90 Å) and one longer (3.18 Å) Mg(3)-Cu(1) bond length. Mn(1) is bonded to two equivalent Mg(2); four Mg(1,1); four Mg(3,3); and two equivalent Cu(1) atoms to form MnMg10Cu2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Mn2 cuboctahedra; corners with six equivalent Mn(1)Mg10Cu2 cuboctahedra; corners with eight Mg(1,1)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(2)Mg10Mn2 cuboctahedra; edges with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Cu(1)Mg10Mn2 cuboctahedra; edges with eight Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; faces with two equivalent Mg(2)Mg10Mn2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; faces with four Mg(3,3)Mg8Mn2Cu2 cuboctahedra; and faces with six equivalent Mg(4)Mg10Cu2 cuboctahedra. Both Mn(1)-Cu(1) bond lengths are 2.92 Å. Cu(1) is bonded to two equivalent Mg(4); four Mg(1,1); four Mg(3,3,3); and two equivalent Mn(1) atoms to form CuMg10Mn2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cu2 cuboctahedra; corners with six equivalent Cu(1)Mg10Mn2 cuboctahedra; corners with eight Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cu2 cuboctahedra; edges with four Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; edges with four equivalent Mn(1)Mg10Cu2 cuboctahedra; edges with eight Mg(1,1)Mg8Mn2Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cu2 cuboctahedra; faces with two equivalent Mn(1)Mg10Cu2 cuboctahedra; faces with two equivalent Cu(1)Mg10Mn2 cuboctahedra; faces with four Mg(1,1)Mg8Mn2Cu2 cuboctahedra; faces with four Mg(3,3,3)Mg8Mn2Cu2 cuboctahedra; and faces with six equivalent Mg(2)Mg10Mn2 cuboctahedra.