Mg6AlSi crystallizes in the orthorhombic Amm2 space group. There are four 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 Al(1), and two equivalent Si(1) atoms to form distorted MgMg8Al2Si2 cuboctahedra that share corners with six equivalent Al(1)Mg10 cuboctahedra, corners with ten equivalent Mg(1)Mg8Al2Si2 cuboctahedra, edges with two equivalent Mg(1)Mg8Al2Si2 cuboctahedra, edges with four equivalent Mg(3)Mg10Al2 cuboctahedra, edges with four equivalent Mg(4)Mg10Si2 cuboctahedra, edges with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, faces with two equivalent Mg(3)Mg10Al2 cuboctahedra, faces with two equivalent Mg(4)Mg10Si2 cuboctahedra, faces with two equivalent Al(1)Mg10 cuboctahedra, faces with four equivalent Mg(1)Mg8Al2Si2 cuboctahedra, and faces with eight equivalent Mg(2)Mg8Al2Si2 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Al(1), and two equivalent Si(1) atoms to form distorted MgMg8Al2Si2 cuboctahedra that share corners with two equivalent Al(1)Mg10 cuboctahedra, corners with four equivalent Mg(3)Mg10Al2 cuboctahedra, corners with four equivalent Mg(4)Mg10Si2 cuboctahedra, corners with ten equivalent Mg(2)Mg8Al2Si2 cuboctahedra, edges with two equivalent Mg(3)Mg10Al2 cuboctahedra, edges with two equivalent Mg(4)Mg10Si2 cuboctahedra, edges with two equivalent Mg(2)Mg8Al2Si2 cuboctahedra, edges with two equivalent Al(1)Mg10 cuboctahedra, edges with four equivalent Mg(1)Mg8Al2Si2 cuboctahedra, faces with two equivalent Mg(3)Mg10Al2 cuboctahedra, faces with two equivalent Mg(4)Mg10Si2 cuboctahedra, faces with two equivalent Al(1)Mg10 cuboctahedra, faces with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, and faces with eight equivalent Mg(1)Mg8Al2Si2 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Al(1) atoms to form distorted MgMg10Al2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Si2 cuboctahedra, corners with six equivalent Mg(3)Mg10Al2 cuboctahedra, corners with eight equivalent Mg(2)Mg8Al2Si2 cuboctahedra, edges with two equivalent Mg(4)Mg10Si2 cuboctahedra, edges with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, edges with four equivalent Al(1)Mg10 cuboctahedra, edges with eight equivalent Mg(1)Mg8Al2Si2 cuboctahedra, faces with two equivalent Mg(3)Mg10Al2 cuboctahedra, faces with two equivalent Mg(4)Mg10Si2 cuboctahedra, faces with two equivalent Al(1)Mg10 cuboctahedra, faces with four equivalent Mg(1)Mg8Al2Si2 cuboctahedra, and faces with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Al2 cuboctahedra, corners with six equivalent Mg(4)Mg10Si2 cuboctahedra, corners with eight equivalent Mg(2)Mg8Al2Si2 cuboctahedra, edges with two equivalent Mg(3)Mg10Al2 cuboctahedra, edges with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, edges with eight equivalent Mg(1)Mg8Al2Si2 cuboctahedra, faces with two equivalent Mg(3)Mg10Al2 cuboctahedra, faces with two equivalent Mg(4)Mg10Si2 cuboctahedra, faces with four equivalent Mg(1)Mg8Al2Si2 cuboctahedra, faces with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, and faces with six equivalent Al(1)Mg10 cuboctahedra. Al(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms to form distorted AlMg10 cuboctahedra that share corners with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, corners with four equivalent Al(1)Mg10 cuboctahedra, corners with twelve equivalent Mg(1)Mg8Al2Si2 cuboctahedra, edges with four equivalent Mg(3)Mg10Al2 cuboctahedra, edges with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, faces with two equivalent Mg(3)Mg10Al2 cuboctahedra, faces with two equivalent Al(1)Mg10 cuboctahedra, faces with four equivalent Mg(1)Mg8Al2Si2 cuboctahedra, faces with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Si2 cuboctahedra. Si(1) is bonded in a 10-coordinate geometry to two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(2) atoms.
Mg6AlSi crystallizes in the orthorhombic Amm2 space group. There are four 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 Al(1), and two equivalent Si(1) atoms to form distorted MgMg8Al2Si2 cuboctahedra that share corners with six equivalent Al(1)Mg10 cuboctahedra, corners with ten equivalent Mg(1)Mg8Al2Si2 cuboctahedra, edges with two equivalent Mg(1)Mg8Al2Si2 cuboctahedra, edges with four equivalent Mg(3)Mg10Al2 cuboctahedra, edges with four equivalent Mg(4)Mg10Si2 cuboctahedra, edges with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, faces with two equivalent Mg(3)Mg10Al2 cuboctahedra, faces with two equivalent Mg(4)Mg10Si2 cuboctahedra, faces with two equivalent Al(1)Mg10 cuboctahedra, faces with four equivalent Mg(1)Mg8Al2Si2 cuboctahedra, and faces with eight equivalent Mg(2)Mg8Al2Si2 cuboctahedra. There is one shorter (3.10 Å) and one longer (3.11 Å) Mg(1)-Mg(1) bond length. Both Mg(1)-Mg(2) bond lengths are 3.09 Å. Both Mg(1)-Mg(3) bond lengths are 3.10 Å. Both Mg(1)-Mg(4) bond lengths are 3.11 Å. There is one shorter (3.03 Å) and one longer (3.05 Å) Mg(1)-Al(1) bond length. Both Mg(1)-Si(1) bond lengths are 3.04 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Al(1), and two equivalent Si(1) atoms to form distorted MgMg8Al2Si2 cuboctahedra that share corners with two equivalent Al(1)Mg10 cuboctahedra, corners with four equivalent Mg(3)Mg10Al2 cuboctahedra, corners with four equivalent Mg(4)Mg10Si2 cuboctahedra, corners with ten equivalent Mg(2)Mg8Al2Si2 cuboctahedra, edges with two equivalent Mg(3)Mg10Al2 cuboctahedra, edges with two equivalent Mg(4)Mg10Si2 cuboctahedra, edges with two equivalent Mg(2)Mg8Al2Si2 cuboctahedra, edges with two equivalent Al(1)Mg10 cuboctahedra, edges with four equivalent Mg(1)Mg8Al2Si2 cuboctahedra, faces with two equivalent Mg(3)Mg10Al2 cuboctahedra, faces with two equivalent Mg(4)Mg10Si2 cuboctahedra, faces with two equivalent Al(1)Mg10 cuboctahedra, faces with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, and faces with eight equivalent Mg(1)Mg8Al2Si2 cuboctahedra. There is one shorter (3.09 Å) and one longer (3.12 Å) Mg(2)-Mg(2) bond length. There is one shorter (2.99 Å) and one longer (3.08 Å) Mg(2)-Mg(3) bond length. There is one shorter (2.97 Å) and one longer (3.10 Å) Mg(2)-Mg(4) bond length. Both Mg(2)-Al(1) bond lengths are 3.09 Å. Both Mg(2)-Si(1) bond lengths are 3.08 Å. In the third Mg site, Mg(3) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Al(1) atoms to form distorted MgMg10Al2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Si2 cuboctahedra, corners with six equivalent Mg(3)Mg10Al2 cuboctahedra, corners with eight equivalent Mg(2)Mg8Al2Si2 cuboctahedra, edges with two equivalent Mg(4)Mg10Si2 cuboctahedra, edges with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, edges with four equivalent Al(1)Mg10 cuboctahedra, edges with eight equivalent Mg(1)Mg8Al2Si2 cuboctahedra, faces with two equivalent Mg(3)Mg10Al2 cuboctahedra, faces with two equivalent Mg(4)Mg10Si2 cuboctahedra, faces with two equivalent Al(1)Mg10 cuboctahedra, faces with four equivalent Mg(1)Mg8Al2Si2 cuboctahedra, and faces with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra. Both Mg(3)-Mg(4) bond lengths are 3.10 Å. Both Mg(3)-Al(1) bond lengths are 3.05 Å. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Al2 cuboctahedra, corners with six equivalent Mg(4)Mg10Si2 cuboctahedra, corners with eight equivalent Mg(2)Mg8Al2Si2 cuboctahedra, edges with two equivalent Mg(3)Mg10Al2 cuboctahedra, edges with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, edges with eight equivalent Mg(1)Mg8Al2Si2 cuboctahedra, faces with two equivalent Mg(3)Mg10Al2 cuboctahedra, faces with two equivalent Mg(4)Mg10Si2 cuboctahedra, faces with four equivalent Mg(1)Mg8Al2Si2 cuboctahedra, faces with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, and faces with six equivalent Al(1)Mg10 cuboctahedra. Both Mg(4)-Si(1) bond lengths are 3.05 Å. Al(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms to form distorted AlMg10 cuboctahedra that share corners with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, corners with four equivalent Al(1)Mg10 cuboctahedra, corners with twelve equivalent Mg(1)Mg8Al2Si2 cuboctahedra, edges with four equivalent Mg(3)Mg10Al2 cuboctahedra, edges with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, faces with two equivalent Mg(3)Mg10Al2 cuboctahedra, faces with two equivalent Al(1)Mg10 cuboctahedra, faces with four equivalent Mg(1)Mg8Al2Si2 cuboctahedra, faces with four equivalent Mg(2)Mg8Al2Si2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Si2 cuboctahedra. Si(1) is bonded in a 10-coordinate geometry to two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(2) atoms.