Mg6MoCr 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 Mo(1), and two equivalent Cr(1) atoms to form distorted MgMg8Cr2Mo2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Cr2 cuboctahedra, corners with ten equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, edges with two equivalent Mg(2)Mg10Cr2 cuboctahedra, edges with two equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, edges with four equivalent Mo(1)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(2)Mg10Cr2 cuboctahedra, faces with two equivalent Mo(1)Mg10Cr2 cuboctahedra, and faces with four equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra. 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 Cr(1) atoms to form distorted MgMg10Cr2 cuboctahedra that share corners with six equivalent Mg(2)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, edges with four equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, faces with two equivalent Mg(2)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, and faces with six equivalent Mo(1)Mg10Cr2 cuboctahedra. In the third Mg site, Mg(3) 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 Mo(1), and two equivalent Cr(1) atoms. In the fourth Mg site, Mg(4) is bonded in a distorted linear geometry to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Mo(1) atoms. Mo(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Cr(1) atoms to form distorted MoMg10Cr2 cuboctahedra that share corners with six equivalent Mo(1)Mg10Cr2 cuboctahedra, edges with eight equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, faces with two equivalent Mo(1)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, and faces with six equivalent Mg(2)Mg10Cr2 cuboctahedra. Cr(1) is bonded in a 12-coordinate geometry to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Mo(1) atoms.
Mg6MoCr 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 Mo(1), and two equivalent Cr(1) atoms to form distorted MgMg8Cr2Mo2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Cr2 cuboctahedra, corners with ten equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, edges with two equivalent Mg(2)Mg10Cr2 cuboctahedra, edges with two equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, edges with four equivalent Mo(1)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(2)Mg10Cr2 cuboctahedra, faces with two equivalent Mo(1)Mg10Cr2 cuboctahedra, and faces with four equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra. There is one shorter (2.86 Å) and one longer (3.11 Å) Mg(1)-Mg(1) bond length. There is one shorter (3.11 Å) and one longer (3.16 Å) Mg(1)-Mg(2) bond length. Both Mg(1)-Mg(3) bond lengths are 2.94 Å. Both Mg(1)-Mg(4) bond lengths are 3.01 Å. Both Mg(1)-Mo(1) bond lengths are 3.04 Å. There is one shorter (2.86 Å) and one longer (3.41 Å) Mg(1)-Cr(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 Cr(1) atoms to form distorted MgMg10Cr2 cuboctahedra that share corners with six equivalent Mg(2)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, edges with four equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, faces with two equivalent Mg(2)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, and faces with six equivalent Mo(1)Mg10Cr2 cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 2.94 Å. All Mg(2)-Mg(3) bond lengths are 3.01 Å. Both Mg(2)-Cr(1) bond lengths are 3.00 Å. In the third Mg site, Mg(3) 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 Mo(1), and two equivalent Cr(1) atoms. There is one shorter (2.91 Å) and one longer (3.06 Å) Mg(3)-Mg(3) bond length. There is one shorter (3.10 Å) and one longer (3.17 Å) Mg(3)-Mg(4) bond length. There is one shorter (2.91 Å) and one longer (3.35 Å) Mg(3)-Mo(1) bond length. Both Mg(3)-Cr(1) bond lengths are 3.07 Å. In the fourth Mg site, Mg(4) is bonded in a distorted linear geometry to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Mo(1) atoms. Both Mg(4)-Mo(1) bond lengths are 2.99 Å. Mo(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Cr(1) atoms to form distorted MoMg10Cr2 cuboctahedra that share corners with six equivalent Mo(1)Mg10Cr2 cuboctahedra, edges with eight equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, faces with two equivalent Mo(1)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Cr2Mo2 cuboctahedra, and faces with six equivalent Mg(2)Mg10Cr2 cuboctahedra. Both Mo(1)-Cr(1) bond lengths are 2.67 Å. Cr(1) is bonded in a 12-coordinate geometry to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Mo(1) atoms.