Mg6HfNi crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted single-bond geometry to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and one Ni(1) atom. 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 Ni(1) atoms to form distorted MgMg10Ni2 cuboctahedra that share corners with six equivalent Mg(2)Mg10Ni2 cuboctahedra, edges with four equivalent Mg(4)Hf2Mg10 cuboctahedra, edges with eight equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Mg10Ni2 cuboctahedra, and faces with four equivalent Mg(3)Hf2Mg8Ni2 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 Hf(1), and two equivalent Ni(1) atoms to form distorted MgHf2Mg8Ni2 cuboctahedra that share corners with four equivalent Mg(4)Hf2Mg10 cuboctahedra, corners with ten equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra, edges with two equivalent Mg(4)Hf2Mg10 cuboctahedra, edges with two equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra, edges with four equivalent Mg(2)Mg10Ni2 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Mg10Ni2 cuboctahedra, and faces with four equivalent Mg(3)Hf2Mg8Ni2 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 Hf(1) atoms to form MgHf2Mg10 cuboctahedra that share corners with six equivalent Mg(4)Hf2Mg10 cuboctahedra, corners with eight equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra, edges with four equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra, edges with four equivalent Mg(2)Mg10Ni2 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Mg10Ni2 cuboctahedra, and faces with four equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra. Hf(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Mg(4), four equivalent Mg(3), and two equivalent Ni(1) atoms. Ni(1) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), four equivalent Mg(3), and two equivalent Hf(1) atoms.
Mg6HfNi crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted single-bond geometry to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and one Ni(1) atom. There is one shorter (3.13 Å) and one longer (3.19 Å) Mg(1)-Mg(2) bond length. Both Mg(1)-Mg(3) bond lengths are 2.95 Å. Both Mg(1)-Mg(4) bond lengths are 3.02 Å. The Mg(1)-Ni(1) bond length is 2.89 Å. 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 Ni(1) atoms to form distorted MgMg10Ni2 cuboctahedra that share corners with six equivalent Mg(2)Mg10Ni2 cuboctahedra, edges with four equivalent Mg(4)Hf2Mg10 cuboctahedra, edges with eight equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Mg10Ni2 cuboctahedra, and faces with four equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 2.98 Å. All Mg(2)-Mg(3) bond lengths are 3.08 Å. Both Mg(2)-Ni(1) bond lengths are 3.05 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 Hf(1), and two equivalent Ni(1) atoms to form distorted MgHf2Mg8Ni2 cuboctahedra that share corners with four equivalent Mg(4)Hf2Mg10 cuboctahedra, corners with ten equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra, edges with two equivalent Mg(4)Hf2Mg10 cuboctahedra, edges with two equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra, edges with four equivalent Mg(2)Mg10Ni2 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Mg10Ni2 cuboctahedra, and faces with four equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra. There is one shorter (2.97 Å) and one longer (3.11 Å) Mg(3)-Mg(3) bond length. There is one shorter (3.05 Å) and one longer (3.27 Å) Mg(3)-Mg(4) bond length. There is one shorter (2.99 Å) and one longer (3.33 Å) Mg(3)-Hf(1) bond length. Both Mg(3)-Ni(1) bond lengths are 3.14 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 Hf(1) atoms to form MgHf2Mg10 cuboctahedra that share corners with six equivalent Mg(4)Hf2Mg10 cuboctahedra, corners with eight equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra, edges with four equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra, edges with four equivalent Mg(2)Mg10Ni2 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Mg10Ni2 cuboctahedra, and faces with four equivalent Mg(3)Hf2Mg8Ni2 cuboctahedra. Both Mg(4)-Hf(1) bond lengths are 3.05 Å. Hf(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Mg(4), four equivalent Mg(3), and two equivalent Ni(1) atoms. Both Hf(1)-Ni(1) bond lengths are 2.71 Å. Ni(1) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), four equivalent Mg(3), and two equivalent Hf(1) atoms.