KMg6Cu crystallizes in the orthorhombic Amm2 space group. K(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Cu(1) atoms to form KMg10Cu2 cuboctahedra that share corners with four equivalent Cu(1)K2Mg10 cuboctahedra, corners with six equivalent K(1)Mg10Cu2 cuboctahedra, corners with eight equivalent Mg(1)K2Mg8Cu2 cuboctahedra, edges with two equivalent Cu(1)K2Mg10 cuboctahedra, edges with four equivalent Mg(1)K2Mg8Cu2 cuboctahedra, faces with two equivalent K(1)Mg10Cu2 cuboctahedra, faces with two equivalent Cu(1)K2Mg10 cuboctahedra, and faces with four equivalent Mg(1)K2Mg8Cu2 cuboctahedra. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent K(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Cu(1) atoms to form distorted MgK2Mg8Cu2 cuboctahedra that share corners with four equivalent K(1)Mg10Cu2 cuboctahedra, corners with four equivalent Cu(1)K2Mg10 cuboctahedra, corners with ten equivalent Mg(1)K2Mg8Cu2 cuboctahedra, edges with two equivalent K(1)Mg10Cu2 cuboctahedra, edges with two equivalent Mg(1)K2Mg8Cu2 cuboctahedra, edges with two equivalent Cu(1)K2Mg10 cuboctahedra, faces with two equivalent K(1)Mg10Cu2 cuboctahedra, faces with two equivalent Cu(1)K2Mg10 cuboctahedra, and faces with four equivalent Mg(1)K2Mg8Cu2 cuboctahedra. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to two equivalent K(1), two equivalent Mg(1), two equivalent Mg(4), and two equivalent Cu(1) atoms. In the third Mg site, Mg(3) is bonded in a distorted water-like geometry to two equivalent Mg(4), four equivalent Mg(1), and two equivalent Cu(1) atoms. In the fourth Mg site, Mg(4) is bonded in a 12-coordinate geometry to two equivalent K(1), two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms. Cu(1) is bonded to two equivalent K(1), two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms to form CuK2Mg10 cuboctahedra that share corners with four equivalent K(1)Mg10Cu2 cuboctahedra, corners with six equivalent Cu(1)K2Mg10 cuboctahedra, corners with eight equivalent Mg(1)K2Mg8Cu2 cuboctahedra, edges with two equivalent K(1)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(1)K2Mg8Cu2 cuboctahedra, faces with two equivalent K(1)Mg10Cu2 cuboctahedra, faces with two equivalent Cu(1)K2Mg10 cuboctahedra, and faces with four equivalent Mg(1)K2Mg8Cu2 cuboctahedra.
KMg6Cu crystallizes in the orthorhombic Amm2 space group. K(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Cu(1) atoms to form KMg10Cu2 cuboctahedra that share corners with four equivalent Cu(1)K2Mg10 cuboctahedra, corners with six equivalent K(1)Mg10Cu2 cuboctahedra, corners with eight equivalent Mg(1)K2Mg8Cu2 cuboctahedra, edges with two equivalent Cu(1)K2Mg10 cuboctahedra, edges with four equivalent Mg(1)K2Mg8Cu2 cuboctahedra, faces with two equivalent K(1)Mg10Cu2 cuboctahedra, faces with two equivalent Cu(1)K2Mg10 cuboctahedra, and faces with four equivalent Mg(1)K2Mg8Cu2 cuboctahedra. Both K(1)-Mg(4) bond lengths are 3.31 Å. There are two shorter (3.30 Å) and two longer (3.31 Å) K(1)-Mg(1) bond lengths. All K(1)-Mg(2) bond lengths are 3.30 Å. Both K(1)-Cu(1) bond lengths are 3.26 Å. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent K(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Cu(1) atoms to form distorted MgK2Mg8Cu2 cuboctahedra that share corners with four equivalent K(1)Mg10Cu2 cuboctahedra, corners with four equivalent Cu(1)K2Mg10 cuboctahedra, corners with ten equivalent Mg(1)K2Mg8Cu2 cuboctahedra, edges with two equivalent K(1)Mg10Cu2 cuboctahedra, edges with two equivalent Mg(1)K2Mg8Cu2 cuboctahedra, edges with two equivalent Cu(1)K2Mg10 cuboctahedra, faces with two equivalent K(1)Mg10Cu2 cuboctahedra, faces with two equivalent Cu(1)K2Mg10 cuboctahedra, and faces with four equivalent Mg(1)K2Mg8Cu2 cuboctahedra. There is one shorter (3.21 Å) and one longer (3.31 Å) Mg(1)-Mg(1) bond length. Both Mg(1)-Mg(2) bond lengths are 3.24 Å. Both Mg(1)-Mg(3) bond lengths are 3.26 Å. Both Mg(1)-Mg(4) bond lengths are 3.19 Å. There is one shorter (3.25 Å) and one longer (3.35 Å) Mg(1)-Cu(1) bond length. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to two equivalent K(1), two equivalent Mg(1), two equivalent Mg(4), and two equivalent Cu(1) atoms. There is one shorter (3.15 Å) and one longer (3.45 Å) Mg(2)-Mg(4) bond length. Both Mg(2)-Cu(1) bond lengths are 3.16 Å. In the third Mg site, Mg(3) is bonded in a distorted water-like geometry to two equivalent Mg(4), four equivalent Mg(1), and two equivalent Cu(1) atoms. Both Mg(3)-Mg(4) bond lengths are 3.26 Å. Both Mg(3)-Cu(1) bond lengths are 3.23 Å. In the fourth Mg site, Mg(4) is bonded in a 12-coordinate geometry to two equivalent K(1), two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms. Cu(1) is bonded to two equivalent K(1), two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms to form CuK2Mg10 cuboctahedra that share corners with four equivalent K(1)Mg10Cu2 cuboctahedra, corners with six equivalent Cu(1)K2Mg10 cuboctahedra, corners with eight equivalent Mg(1)K2Mg8Cu2 cuboctahedra, edges with two equivalent K(1)Mg10Cu2 cuboctahedra, edges with four equivalent Mg(1)K2Mg8Cu2 cuboctahedra, faces with two equivalent K(1)Mg10Cu2 cuboctahedra, faces with two equivalent Cu(1)K2Mg10 cuboctahedra, and faces with four equivalent Mg(1)K2Mg8Cu2 cuboctahedra.