Mg6CrSi 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 Cr(1), and two equivalent Si(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 Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Si(1)Mg10Cr2 cuboctahedra, corners with six equivalent Mg(2)Mg10Si2 cuboctahedra, edges with two equivalent Si(1)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with eight equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(2)Mg10Si2 cuboctahedra, faces with two equivalent Si(1)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, and faces with six equivalent Cr(1)Mg10Si2 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 Cr(1), and two equivalent Si(1) atoms to form distorted MgMg8Cr2Si2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with four equivalent Cr(1)Mg10Si2 cuboctahedra, corners with ten equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with two equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, edges with two equivalent Cr(1)Mg10Si2 cuboctahedra, edges with four equivalent Mg(2)Mg10Si2 cuboctahedra, edges with four equivalent Si(1)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(2)Mg10Si2 cuboctahedra, faces with two equivalent Cr(1)Mg10Si2 cuboctahedra, faces with two equivalent Si(1)Mg10Cr2 cuboctahedra, and faces with four equivalent Mg(3)Mg8Cr2Si2 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 Cr(1) atoms to form MgMg10Cr2 cuboctahedra that share corners with four equivalent Cr(1)Mg10Si2 cuboctahedra, corners with six equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, edges with two equivalent Cr(1)Mg10Si2 cuboctahedra, edges with four equivalent Mg(2)Mg10Si2 cuboctahedra, edges with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(2)Mg10Si2 cuboctahedra, faces with two equivalent Cr(1)Mg10Si2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, and faces with six equivalent Si(1)Mg10Cr2 cuboctahedra. Cr(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Si(1) atoms to form CrMg10Si2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with six equivalent Cr(1)Mg10Si2 cuboctahedra, corners with eight equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, edges with four equivalent Si(1)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Mg10Si2 cuboctahedra, faces with two equivalent Si(1)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, and faces with six equivalent Mg(2)Mg10Si2 cuboctahedra. Si(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Cr(1) atoms to form distorted SiMg10Cr2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Si2 cuboctahedra, corners with six equivalent Si(1)Mg10Cr2 cuboctahedra, edges with two equivalent Mg(2)Mg10Si2 cuboctahedra, edges with four equivalent Cr(1)Mg10Si2 cuboctahedra, edges with eight equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, faces with two equivalent Mg(2)Mg10Si2 cuboctahedra, faces with two equivalent Cr(1)Mg10Si2 cuboctahedra, faces with two equivalent Si(1)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Cr2 cuboctahedra.
Mg6CrSi 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 Cr(1), and two equivalent Si(1) atoms. There is one shorter (3.02 Å) and one longer (3.19 Å) Mg(1)-Mg(1) bond length. There is one shorter (3.05 Å) and one longer (3.11 Å) Mg(1)-Mg(2) bond length. Both Mg(1)-Mg(3) bond lengths are 3.04 Å. Both Mg(1)-Mg(4) bond lengths are 3.01 Å. Both Mg(1)-Cr(1) bond lengths are 3.00 Å. There is one shorter (2.91 Å) and one longer (3.24 Å) Mg(1)-Si(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 Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Si(1)Mg10Cr2 cuboctahedra, corners with six equivalent Mg(2)Mg10Si2 cuboctahedra, edges with two equivalent Si(1)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with eight equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(2)Mg10Si2 cuboctahedra, faces with two equivalent Si(1)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, and faces with six equivalent Cr(1)Mg10Si2 cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.00 Å. All Mg(2)-Mg(3) bond lengths are 3.02 Å. Both Mg(2)-Si(1) bond lengths are 3.11 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 Cr(1), and two equivalent Si(1) atoms to form distorted MgMg8Cr2Si2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with four equivalent Cr(1)Mg10Si2 cuboctahedra, corners with ten equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with two equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, edges with two equivalent Cr(1)Mg10Si2 cuboctahedra, edges with four equivalent Mg(2)Mg10Si2 cuboctahedra, edges with four equivalent Si(1)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(2)Mg10Si2 cuboctahedra, faces with two equivalent Cr(1)Mg10Si2 cuboctahedra, faces with two equivalent Si(1)Mg10Cr2 cuboctahedra, and faces with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra. There is one shorter (3.04 Å) and one longer (3.18 Å) Mg(3)-Mg(3) bond length. There is one shorter (3.07 Å) and one longer (3.09 Å) Mg(3)-Mg(4) bond length. There is one shorter (2.94 Å) and one longer (3.21 Å) Mg(3)-Cr(1) bond length. Both Mg(3)-Si(1) bond lengths are 3.02 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 Cr(1) atoms to form MgMg10Cr2 cuboctahedra that share corners with four equivalent Cr(1)Mg10Si2 cuboctahedra, corners with six equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, edges with two equivalent Cr(1)Mg10Si2 cuboctahedra, edges with four equivalent Mg(2)Mg10Si2 cuboctahedra, edges with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(2)Mg10Si2 cuboctahedra, faces with two equivalent Cr(1)Mg10Si2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, and faces with six equivalent Si(1)Mg10Cr2 cuboctahedra. Both Mg(4)-Cr(1) bond lengths are 3.11 Å. Cr(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Si(1) atoms to form CrMg10Si2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with six equivalent Cr(1)Mg10Si2 cuboctahedra, corners with eight equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, edges with four equivalent Si(1)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Mg10Si2 cuboctahedra, faces with two equivalent Si(1)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, and faces with six equivalent Mg(2)Mg10Si2 cuboctahedra. Both Cr(1)-Si(1) bond lengths are 2.87 Å. Si(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Cr(1) atoms to form distorted SiMg10Cr2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Si2 cuboctahedra, corners with six equivalent Si(1)Mg10Cr2 cuboctahedra, edges with two equivalent Mg(2)Mg10Si2 cuboctahedra, edges with four equivalent Cr(1)Mg10Si2 cuboctahedra, edges with eight equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, faces with two equivalent Mg(2)Mg10Si2 cuboctahedra, faces with two equivalent Cr(1)Mg10Si2 cuboctahedra, faces with two equivalent Si(1)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(3)Mg8Cr2Si2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Cr2 cuboctahedra.