Mg6NiCu crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Ni(1), and two equivalent Cu(1) atoms. In the second Mg site, Mg(2) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Cu(1) atoms to form distorted MgMg10Cu2 cuboctahedra that share corners with four equivalent Cu(1)Mg10Ni2 cuboctahedra, corners with six equivalent Mg(2)Mg10Cu2 cuboctahedra, edges with two equivalent Cu(1)Mg10Ni2 cuboctahedra, edges with four equivalent Mg(4)Mg10Ni2 cuboctahedra, edges with eight equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, faces with two equivalent Mg(2)Mg10Cu2 cuboctahedra, faces with two equivalent Mg(4)Mg10Ni2 cuboctahedra, faces with two equivalent Cu(1)Mg10Ni2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, and faces with six equivalent Ni(1)Mg10Cu2 cuboctahedra. In the third 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 Ni(1), and two equivalent Cu(1) atoms to form distorted MgMg8Cu2Ni2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Ni2 cuboctahedra, corners with four equivalent Ni(1)Mg10Cu2 cuboctahedra, corners with ten equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, edges with two equivalent Mg(4)Mg10Ni2 cuboctahedra, edges with two equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, edges with two equivalent Ni(1)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(2)Mg10Cu2 cuboctahedra, edges with four equivalent Cu(1)Mg10Ni2 cuboctahedra, faces with two equivalent Mg(2)Mg10Cu2 cuboctahedra, faces with two equivalent Mg(4)Mg10Ni2 cuboctahedra, faces with two equivalent Ni(1)Mg10Cu2 cuboctahedra, faces with two equivalent Cu(1)Mg10Ni2 cuboctahedra, and faces with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Ni(1) atoms to form distorted MgMg10Ni2 cuboctahedra that share corners with four equivalent Ni(1)Mg10Cu2 cuboctahedra, corners with six equivalent Mg(4)Mg10Ni2 cuboctahedra, corners with eight equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, edges with two equivalent Ni(1)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(2)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, faces with two equivalent Mg(2)Mg10Cu2 cuboctahedra, faces with two equivalent Mg(4)Mg10Ni2 cuboctahedra, faces with two equivalent Ni(1)Mg10Cu2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, and faces with six equivalent Cu(1)Mg10Ni2 cuboctahedra. Ni(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Cu(1) atoms to form distorted NiMg10Cu2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Ni2 cuboctahedra, corners with six equivalent Ni(1)Mg10Cu2 cuboctahedra, corners with eight equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, edges with two equivalent Mg(4)Mg10Ni2 cuboctahedra, edges with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, edges with four equivalent Cu(1)Mg10Ni2 cuboctahedra, faces with two equivalent Mg(4)Mg10Ni2 cuboctahedra, faces with two equivalent Ni(1)Mg10Cu2 cuboctahedra, faces with two equivalent Cu(1)Mg10Ni2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, and faces with six equivalent Mg(2)Mg10Cu2 cuboctahedra. Cu(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Ni(1) atoms to form distorted CuMg10Ni2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Cu2 cuboctahedra, corners with six equivalent Cu(1)Mg10Ni2 cuboctahedra, edges with two equivalent Mg(2)Mg10Cu2 cuboctahedra, edges with four equivalent Ni(1)Mg10Cu2 cuboctahedra, edges with eight equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, faces with two equivalent Mg(2)Mg10Cu2 cuboctahedra, faces with two equivalent Ni(1)Mg10Cu2 cuboctahedra, faces with two equivalent Cu(1)Mg10Ni2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Ni2 cuboctahedra.
Mg6NiCu crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Ni(1), and two equivalent Cu(1) atoms. There is one shorter (2.78 Å) and one longer (3.11 Å) Mg(1)-Mg(1) bond length. There is one shorter (2.92 Å) and one longer (3.00 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 2.95 Å. Both Mg(1)-Ni(1) bond lengths are 2.86 Å. There is one shorter (2.82 Å) and one longer (3.09 Å) Mg(1)-Cu(1) bond length. In the second Mg site, Mg(2) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Cu(1) atoms to form distorted MgMg10Cu2 cuboctahedra that share corners with four equivalent Cu(1)Mg10Ni2 cuboctahedra, corners with six equivalent Mg(2)Mg10Cu2 cuboctahedra, edges with two equivalent Cu(1)Mg10Ni2 cuboctahedra, edges with four equivalent Mg(4)Mg10Ni2 cuboctahedra, edges with eight equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, faces with two equivalent Mg(2)Mg10Cu2 cuboctahedra, faces with two equivalent Mg(4)Mg10Ni2 cuboctahedra, faces with two equivalent Cu(1)Mg10Ni2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, and faces with six equivalent Ni(1)Mg10Cu2 cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 2.96 Å. All Mg(2)-Mg(3) bond lengths are 2.94 Å. Both Mg(2)-Cu(1) bond lengths are 2.95 Å. In the third 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 Ni(1), and two equivalent Cu(1) atoms to form distorted MgMg8Cu2Ni2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Ni2 cuboctahedra, corners with four equivalent Ni(1)Mg10Cu2 cuboctahedra, corners with ten equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, edges with two equivalent Mg(4)Mg10Ni2 cuboctahedra, edges with two equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, edges with two equivalent Ni(1)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(2)Mg10Cu2 cuboctahedra, edges with four equivalent Cu(1)Mg10Ni2 cuboctahedra, faces with two equivalent Mg(2)Mg10Cu2 cuboctahedra, faces with two equivalent Mg(4)Mg10Ni2 cuboctahedra, faces with two equivalent Ni(1)Mg10Cu2 cuboctahedra, faces with two equivalent Cu(1)Mg10Ni2 cuboctahedra, and faces with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra. There is one shorter (2.82 Å) and one longer (3.07 Å) Mg(3)-Mg(3) bond length. There is one shorter (2.93 Å) and one longer (2.98 Å) Mg(3)-Mg(4) bond length. There is one shorter (2.89 Å) and one longer (3.03 Å) Mg(3)-Ni(1) bond length. Both Mg(3)-Cu(1) bond lengths are 2.89 Å. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Ni(1) atoms to form distorted MgMg10Ni2 cuboctahedra that share corners with four equivalent Ni(1)Mg10Cu2 cuboctahedra, corners with six equivalent Mg(4)Mg10Ni2 cuboctahedra, corners with eight equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, edges with two equivalent Ni(1)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(2)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, faces with two equivalent Mg(2)Mg10Cu2 cuboctahedra, faces with two equivalent Mg(4)Mg10Ni2 cuboctahedra, faces with two equivalent Ni(1)Mg10Cu2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, and faces with six equivalent Cu(1)Mg10Ni2 cuboctahedra. Both Mg(4)-Ni(1) bond lengths are 2.95 Å. Ni(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Cu(1) atoms to form distorted NiMg10Cu2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Ni2 cuboctahedra, corners with six equivalent Ni(1)Mg10Cu2 cuboctahedra, corners with eight equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, edges with two equivalent Mg(4)Mg10Ni2 cuboctahedra, edges with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, edges with four equivalent Cu(1)Mg10Ni2 cuboctahedra, faces with two equivalent Mg(4)Mg10Ni2 cuboctahedra, faces with two equivalent Ni(1)Mg10Cu2 cuboctahedra, faces with two equivalent Cu(1)Mg10Ni2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, and faces with six equivalent Mg(2)Mg10Cu2 cuboctahedra. Both Ni(1)-Cu(1) bond lengths are 2.96 Å. Cu(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Ni(1) atoms to form distorted CuMg10Ni2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Cu2 cuboctahedra, corners with six equivalent Cu(1)Mg10Ni2 cuboctahedra, edges with two equivalent Mg(2)Mg10Cu2 cuboctahedra, edges with four equivalent Ni(1)Mg10Cu2 cuboctahedra, edges with eight equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, faces with two equivalent Mg(2)Mg10Cu2 cuboctahedra, faces with two equivalent Ni(1)Mg10Cu2 cuboctahedra, faces with two equivalent Cu(1)Mg10Ni2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cu2Ni2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Ni2 cuboctahedra.