Mg3Hf is Magnesium-derived structured and crystallizes in the orthorhombic Pmm2 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), four equivalent Mg(3), and four equivalent Hf(1) atoms to form MgHf4Mg8 cuboctahedra that share corners with eight equivalent Hf(1)Hf2Mg10 cuboctahedra, corners with ten equivalent Mg(1)Hf4Mg8 cuboctahedra, edges with two equivalent Mg(1)Hf4Mg8 cuboctahedra, edges with four equivalent Mg(2)Hf4Mg8 cuboctahedra, edges with four equivalent Hf(1)Hf2Mg10 cuboctahedra, edges with eight equivalent Mg(3)Hf2Mg10 cuboctahedra, faces with four equivalent Mg(3)Hf2Mg10 cuboctahedra, faces with four equivalent Mg(1)Hf4Mg8 cuboctahedra, faces with four equivalent Hf(1)Hf2Mg10 cuboctahedra, and faces with eight equivalent Mg(2)Hf4Mg8 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), four equivalent Mg(3), and four equivalent Hf(1) atoms to form MgHf4Mg8 cuboctahedra that share corners with eight equivalent Mg(3)Hf2Mg10 cuboctahedra, corners with ten equivalent Mg(2)Hf4Mg8 cuboctahedra, edges with two equivalent Mg(2)Hf4Mg8 cuboctahedra, edges with four equivalent Mg(3)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(1)Hf4Mg8 cuboctahedra, edges with eight equivalent Hf(1)Hf2Mg10 cuboctahedra, faces with four equivalent Mg(3)Hf2Mg10 cuboctahedra, faces with four equivalent Mg(2)Hf4Mg8 cuboctahedra, faces with four equivalent Hf(1)Hf2Mg10 cuboctahedra, and faces with eight equivalent Mg(1)Hf4Mg8 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Hf(1) atoms to form MgHf2Mg10 cuboctahedra that share corners with eight equivalent Mg(2)Hf4Mg8 cuboctahedra, corners with ten equivalent Mg(3)Hf2Mg10 cuboctahedra, edges with two equivalent Mg(3)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(2)Hf4Mg8 cuboctahedra, edges with four equivalent Hf(1)Hf2Mg10 cuboctahedra, edges with eight equivalent Mg(1)Hf4Mg8 cuboctahedra, faces with four equivalent Mg(3)Hf2Mg10 cuboctahedra, faces with four equivalent Mg(1)Hf4Mg8 cuboctahedra, faces with four equivalent Mg(2)Hf4Mg8 cuboctahedra, and faces with eight equivalent Hf(1)Hf2Mg10 cuboctahedra. Hf(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Hf(1) atoms to form HfHf2Mg10 cuboctahedra that share corners with eight equivalent Mg(1)Hf4Mg8 cuboctahedra, corners with ten equivalent Hf(1)Hf2Mg10 cuboctahedra, edges with two equivalent Hf(1)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(3)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(1)Hf4Mg8 cuboctahedra, edges with eight equivalent Mg(2)Hf4Mg8 cuboctahedra, faces with four equivalent Mg(1)Hf4Mg8 cuboctahedra, faces with four equivalent Mg(2)Hf4Mg8 cuboctahedra, faces with four equivalent Hf(1)Hf2Mg10 cuboctahedra, and faces with eight equivalent Mg(3)Hf2Mg10 cuboctahedra.
Mg3Hf is Magnesium-derived structured and crystallizes in the orthorhombic Pmm2 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), four equivalent Mg(3), and four equivalent Hf(1) atoms to form MgHf4Mg8 cuboctahedra that share corners with eight equivalent Hf(1)Hf2Mg10 cuboctahedra, corners with ten equivalent Mg(1)Hf4Mg8 cuboctahedra, edges with two equivalent Mg(1)Hf4Mg8 cuboctahedra, edges with four equivalent Mg(2)Hf4Mg8 cuboctahedra, edges with four equivalent Hf(1)Hf2Mg10 cuboctahedra, edges with eight equivalent Mg(3)Hf2Mg10 cuboctahedra, faces with four equivalent Mg(3)Hf2Mg10 cuboctahedra, faces with four equivalent Mg(1)Hf4Mg8 cuboctahedra, faces with four equivalent Hf(1)Hf2Mg10 cuboctahedra, and faces with eight equivalent Mg(2)Hf4Mg8 cuboctahedra. Both Mg(1)-Mg(1) bond lengths are 3.03 Å. Both Mg(1)-Mg(2) bond lengths are 3.17 Å. All Mg(1)-Mg(3) bond lengths are 3.16 Å. There are two shorter (3.26 Å) and two longer (3.28 Å) Mg(1)-Hf(1) bond lengths. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), four equivalent Mg(3), and four equivalent Hf(1) atoms to form MgHf4Mg8 cuboctahedra that share corners with eight equivalent Mg(3)Hf2Mg10 cuboctahedra, corners with ten equivalent Mg(2)Hf4Mg8 cuboctahedra, edges with two equivalent Mg(2)Hf4Mg8 cuboctahedra, edges with four equivalent Mg(3)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(1)Hf4Mg8 cuboctahedra, edges with eight equivalent Hf(1)Hf2Mg10 cuboctahedra, faces with four equivalent Mg(3)Hf2Mg10 cuboctahedra, faces with four equivalent Mg(2)Hf4Mg8 cuboctahedra, faces with four equivalent Hf(1)Hf2Mg10 cuboctahedra, and faces with eight equivalent Mg(1)Hf4Mg8 cuboctahedra. Both Mg(2)-Mg(2) bond lengths are 3.03 Å. There are two shorter (3.18 Å) and two longer (3.35 Å) Mg(2)-Mg(3) bond lengths. All Mg(2)-Hf(1) bond lengths are 3.13 Å. In the third Mg site, Mg(3) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Hf(1) atoms to form MgHf2Mg10 cuboctahedra that share corners with eight equivalent Mg(2)Hf4Mg8 cuboctahedra, corners with ten equivalent Mg(3)Hf2Mg10 cuboctahedra, edges with two equivalent Mg(3)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(2)Hf4Mg8 cuboctahedra, edges with four equivalent Hf(1)Hf2Mg10 cuboctahedra, edges with eight equivalent Mg(1)Hf4Mg8 cuboctahedra, faces with four equivalent Mg(3)Hf2Mg10 cuboctahedra, faces with four equivalent Mg(1)Hf4Mg8 cuboctahedra, faces with four equivalent Mg(2)Hf4Mg8 cuboctahedra, and faces with eight equivalent Hf(1)Hf2Mg10 cuboctahedra. Both Mg(3)-Mg(3) bond lengths are 3.03 Å. Both Mg(3)-Hf(1) bond lengths are 3.12 Å. Hf(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Hf(1) atoms to form HfHf2Mg10 cuboctahedra that share corners with eight equivalent Mg(1)Hf4Mg8 cuboctahedra, corners with ten equivalent Hf(1)Hf2Mg10 cuboctahedra, edges with two equivalent Hf(1)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(3)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(1)Hf4Mg8 cuboctahedra, edges with eight equivalent Mg(2)Hf4Mg8 cuboctahedra, faces with four equivalent Mg(1)Hf4Mg8 cuboctahedra, faces with four equivalent Mg(2)Hf4Mg8 cuboctahedra, faces with four equivalent Hf(1)Hf2Mg10 cuboctahedra, and faces with eight equivalent Mg(3)Hf2Mg10 cuboctahedra. Both Hf(1)-Hf(1) bond lengths are 3.03 Å.