NaMg6Hf crystallizes in the orthorhombic Amm2 space group. Na(1) is bonded to two equivalent Mg(2); four Mg(1,1,1); four equivalent Mg(3); and two equivalent Hf(1) atoms to form NaHf2Mg10 cuboctahedra that share corners with four equivalent Mg(2)Na2Mg10 cuboctahedra; corners with six equivalent Na(1)Hf2Mg10 cuboctahedra; corners with eight Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(2)Na2Mg10 cuboctahedra; edges with four Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Hf(1)Na2Mg10 cuboctahedra; edges with eight Mg(3,3)Na2Hf2Mg8 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; faces with four equivalent Mg(3)Na2Hf2Mg8 cuboctahedra; and faces with six equivalent Mg(4)Hf2Mg10 cuboctahedra. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Na(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with four equivalent Na(1)Hf2Mg10 cuboctahedra; corners with four equivalent Mg(2)Na2Mg10 cuboctahedra; corners with ten Mg(1,1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Na(1)Hf2Mg10 cuboctahedra; edges with two equivalent Mg(1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(2)Na2Mg10 cuboctahedra; edges with four equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with four equivalent Mg(3)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Hf(1)Na2Mg10 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(1,1)Na2Hf2Mg8 cuboctahedra; and faces with eight Mg(3,3)Na2Hf2Mg8 cuboctahedra. In the second Mg site, Mg(1) is bonded to two equivalent Na(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with four equivalent Na(1)Hf2Mg10 cuboctahedra; corners with four equivalent Mg(2)Na2Mg10 cuboctahedra; corners with ten Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Na(1)Hf2Mg10 cuboctahedra; edges with two equivalent Mg(1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(2)Na2Mg10 cuboctahedra; edges with four equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with four equivalent Mg(3)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Hf(1)Na2Mg10 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(1,1)Na2Hf2Mg8 cuboctahedra; and faces with eight Mg(3,3)Na2Hf2Mg8 cuboctahedra. In the third Mg site, Mg(2) is bonded to two equivalent Na(1); two equivalent Mg(4); four Mg(1,1,1); and four Mg(3,3) atoms to form distorted MgNa2Mg10 cuboctahedra that share corners with four equivalent Na(1)Hf2Mg10 cuboctahedra; corners with six equivalent Mg(2)Na2Mg10 cuboctahedra; corners with eight Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Na(1)Hf2Mg10 cuboctahedra; edges with four equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with four Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; edges with eight Mg(3,3)Na2Hf2Mg8 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with four Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; faces with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; and faces with six equivalent Hf(1)Na2Mg10 cuboctahedra. In the fourth Mg site, Mg(3) is bonded to two equivalent Na(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with four equivalent Mg(4)Hf2Mg10 cuboctahedra; corners with four equivalent Hf(1)Na2Mg10 cuboctahedra; corners with ten Mg(3,3)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with two equivalent Mg(3)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Hf(1)Na2Mg10 cuboctahedra; edges with four equivalent Na(1)Hf2Mg10 cuboctahedra; edges with four equivalent Mg(1)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; and faces with eight Mg(1,1,1)Na2Hf2Mg8 cuboctahedra. In the fifth Mg site, Mg(3) is bonded to two equivalent Na(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with four equivalent Mg(4)Hf2Mg10 cuboctahedra; corners with four equivalent Hf(1)Na2Mg10 cuboctahedra; corners with ten Mg(3,3)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with two equivalent Mg(3)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Hf(1)Na2Mg10 cuboctahedra; edges with four equivalent Na(1)Hf2Mg10 cuboctahedra; edges with four equivalent Mg(1)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; and faces with eight Mg(1,1)Na2Hf2Mg8 cuboctahedra. In the sixth Mg site, Mg(4) is bonded to two equivalent Mg(2); four Mg(1,1); four Mg(3,3); and two equivalent Hf(1) atoms to form MgHf2Mg10 cuboctahedra that share corners with four equivalent Hf(1)Na2Mg10 cuboctahedra; corners with six equivalent Mg(4)Hf2Mg10 cuboctahedra; corners with eight Mg(3,3)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Hf(1)Na2Mg10 cuboctahedra; edges with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Mg(2)Na2Mg10 cuboctahedra; edges with eight Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(1,1)Na2Hf2Mg8 cuboctahedra; faces with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; and faces with six equivalent Na(1)Hf2Mg10 cuboctahedra. In the seventh Mg site, Mg(1) is bonded to two equivalent Na(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with four equivalent Na(1)Hf2Mg10 cuboctahedra; corners with four equivalent Mg(2)Na2Mg10 cuboctahedra; corners with ten Mg(1,1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Na(1)Hf2Mg10 cuboctahedra; edges with two equivalent Mg(1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(2)Na2Mg10 cuboctahedra; edges with four equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with four equivalent Mg(3)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Hf(1)Na2Mg10 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(1,1)Na2Hf2Mg8 cuboctahedra; and faces with eight equivalent Mg(3)Na2Hf2Mg8 cuboctahedra. Hf(1) is bonded to two equivalent Na(1); two equivalent Mg(4); four Mg(1,1); and four Mg(3,3) atoms to form HfNa2Mg10 cuboctahedra that share corners with four equivalent Mg(4)Hf2Mg10 cuboctahedra; corners with six equivalent Hf(1)Na2Mg10 cuboctahedra; corners with eight Mg(3,3)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with four equivalent Na(1)Hf2Mg10 cuboctahedra; edges with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; edges with eight Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(1,1)Na2Hf2Mg8 cuboctahedra; faces with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; and faces with six equivalent Mg(2)Na2Mg10 cuboctahedra.
NaMg6Hf crystallizes in the orthorhombic Amm2 space group. Na(1) is bonded to two equivalent Mg(2); four Mg(1,1,1); four equivalent Mg(3); and two equivalent Hf(1) atoms to form NaHf2Mg10 cuboctahedra that share corners with four equivalent Mg(2)Na2Mg10 cuboctahedra; corners with six equivalent Na(1)Hf2Mg10 cuboctahedra; corners with eight Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(2)Na2Mg10 cuboctahedra; edges with four Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Hf(1)Na2Mg10 cuboctahedra; edges with eight Mg(3,3)Na2Hf2Mg8 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; faces with four equivalent Mg(3)Na2Hf2Mg8 cuboctahedra; and faces with six equivalent Mg(4)Hf2Mg10 cuboctahedra. Both Na(1)-Mg(2) bond lengths are 3.23 Å. There are two shorter (3.20 Å) and two longer (3.25 Å) Na(1)-Mg(1,1,1) bond lengths. All Na(1)-Mg(3) bond lengths are 3.19 Å. Both Na(1)-Hf(1) bond lengths are 3.27 Å. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Na(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with four equivalent Na(1)Hf2Mg10 cuboctahedra; corners with four equivalent Mg(2)Na2Mg10 cuboctahedra; corners with ten Mg(1,1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Na(1)Hf2Mg10 cuboctahedra; edges with two equivalent Mg(1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(2)Na2Mg10 cuboctahedra; edges with four equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with four equivalent Mg(3)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Hf(1)Na2Mg10 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(1,1)Na2Hf2Mg8 cuboctahedra; and faces with eight Mg(3,3)Na2Hf2Mg8 cuboctahedra. There is one shorter (3.13 Å) and one longer (3.33 Å) Mg(1)-Mg(1) bond length. Both Mg(1)-Mg(2) bond lengths are 3.23 Å. Both Mg(1)-Mg(3) bond lengths are 3.20 Å. Both Mg(1)-Mg(4) bond lengths are 3.20 Å. Both Mg(1)-Hf(1) bond lengths are 3.13 Å. In the second Mg site, Mg(1) is bonded to two equivalent Na(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with four equivalent Na(1)Hf2Mg10 cuboctahedra; corners with four equivalent Mg(2)Na2Mg10 cuboctahedra; corners with ten Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Na(1)Hf2Mg10 cuboctahedra; edges with two equivalent Mg(1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(2)Na2Mg10 cuboctahedra; edges with four equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with four equivalent Mg(3)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Hf(1)Na2Mg10 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(1,1)Na2Hf2Mg8 cuboctahedra; and faces with eight Mg(3,3)Na2Hf2Mg8 cuboctahedra. Both Mg(1)-Mg(2) bond lengths are 3.23 Å. Both Mg(1)-Mg(3) bond lengths are 3.20 Å. Both Mg(1)-Mg(4) bond lengths are 3.20 Å. Both Mg(1)-Hf(1) bond lengths are 3.13 Å. In the third Mg site, Mg(2) is bonded to two equivalent Na(1); two equivalent Mg(4); four Mg(1,1,1); and four Mg(3,3) atoms to form distorted MgNa2Mg10 cuboctahedra that share corners with four equivalent Na(1)Hf2Mg10 cuboctahedra; corners with six equivalent Mg(2)Na2Mg10 cuboctahedra; corners with eight Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Na(1)Hf2Mg10 cuboctahedra; edges with four equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with four Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; edges with eight Mg(3,3)Na2Hf2Mg8 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with four Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; faces with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; and faces with six equivalent Hf(1)Na2Mg10 cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.21 Å. The Mg(2)-Mg(1) bond length is 3.23 Å. All Mg(2)-Mg(3,3) bond lengths are 3.19 Å. In the fourth Mg site, Mg(3) is bonded to two equivalent Na(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with four equivalent Mg(4)Hf2Mg10 cuboctahedra; corners with four equivalent Hf(1)Na2Mg10 cuboctahedra; corners with ten Mg(3,3)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with two equivalent Mg(3)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Hf(1)Na2Mg10 cuboctahedra; edges with four equivalent Na(1)Hf2Mg10 cuboctahedra; edges with four equivalent Mg(1)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; and faces with eight Mg(1,1,1)Na2Hf2Mg8 cuboctahedra. Both Mg(3)-Mg(3) bond lengths are 3.23 Å. There is one shorter (3.19 Å) and one longer (3.26 Å) Mg(3)-Mg(4) bond length. There is one shorter (3.13 Å) and one longer (3.32 Å) Mg(3)-Hf(1) bond length. In the fifth Mg site, Mg(3) is bonded to two equivalent Na(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with four equivalent Mg(4)Hf2Mg10 cuboctahedra; corners with four equivalent Hf(1)Na2Mg10 cuboctahedra; corners with ten Mg(3,3)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with two equivalent Mg(3)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Hf(1)Na2Mg10 cuboctahedra; edges with four equivalent Na(1)Hf2Mg10 cuboctahedra; edges with four equivalent Mg(1)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; and faces with eight Mg(1,1)Na2Hf2Mg8 cuboctahedra. Both Mg(3)-Na(1) bond lengths are 3.19 Å. There is one shorter (3.19 Å) and one longer (3.26 Å) Mg(3)-Mg(4) bond length. There is one shorter (3.13 Å) and one longer (3.32 Å) Mg(3)-Hf(1) bond length. In the sixth Mg site, Mg(4) is bonded to two equivalent Mg(2); four Mg(1,1); four Mg(3,3); and two equivalent Hf(1) atoms to form MgHf2Mg10 cuboctahedra that share corners with four equivalent Hf(1)Na2Mg10 cuboctahedra; corners with six equivalent Mg(4)Hf2Mg10 cuboctahedra; corners with eight Mg(3,3)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Hf(1)Na2Mg10 cuboctahedra; edges with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Mg(2)Na2Mg10 cuboctahedra; edges with eight Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(1,1)Na2Hf2Mg8 cuboctahedra; faces with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; and faces with six equivalent Na(1)Hf2Mg10 cuboctahedra. Both Mg(4)-Mg(1) bond lengths are 3.20 Å. Both Mg(4)-Hf(1) bond lengths are 3.23 Å. In the seventh Mg site, Mg(1) is bonded to two equivalent Na(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms to form distorted MgNa2Hf2Mg8 cuboctahedra that share corners with four equivalent Na(1)Hf2Mg10 cuboctahedra; corners with four equivalent Mg(2)Na2Mg10 cuboctahedra; corners with ten Mg(1,1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Na(1)Hf2Mg10 cuboctahedra; edges with two equivalent Mg(1)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(2)Na2Mg10 cuboctahedra; edges with four equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with four equivalent Mg(3)Na2Hf2Mg8 cuboctahedra; edges with four equivalent Hf(1)Na2Mg10 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(2)Na2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(1,1)Na2Hf2Mg8 cuboctahedra; and faces with eight equivalent Mg(3)Na2Hf2Mg8 cuboctahedra. There is one shorter (3.13 Å) and one longer (3.33 Å) Mg(1)-Mg(1) bond length. Both Mg(1)-Mg(3) bond lengths are 3.20 Å. Both Mg(1)-Hf(1) bond lengths are 3.13 Å. Hf(1) is bonded to two equivalent Na(1); two equivalent Mg(4); four Mg(1,1); and four Mg(3,3) atoms to form HfNa2Mg10 cuboctahedra that share corners with four equivalent Mg(4)Hf2Mg10 cuboctahedra; corners with six equivalent Hf(1)Na2Mg10 cuboctahedra; corners with eight Mg(3,3)Na2Hf2Mg8 cuboctahedra; edges with two equivalent Mg(4)Hf2Mg10 cuboctahedra; edges with four equivalent Na(1)Hf2Mg10 cuboctahedra; edges with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; edges with eight Mg(1,1,1)Na2Hf2Mg8 cuboctahedra; faces with two equivalent Na(1)Hf2Mg10 cuboctahedra; faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra; faces with two equivalent Hf(1)Na2Mg10 cuboctahedra; faces with four Mg(1,1)Na2Hf2Mg8 cuboctahedra; faces with four Mg(3,3)Na2Hf2Mg8 cuboctahedra; and faces with six equivalent Mg(2)Na2Mg10 cuboctahedra.