Mg14NbSb crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2), two equivalent Mg(6), four equivalent Mg(4), and four equivalent Mg(5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Sb(1)Mg10Nb2 cuboctahedra, corners with six equivalent Mg(1)Mg12 cuboctahedra, corners with eight equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with four equivalent Mg(6)Mg11Nb cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with eight equivalent Mg(5)Mg10NbSb cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Nb(1)Mg10Sb2 cuboctahedra, faces with four equivalent Mg(5)Mg10NbSb cuboctahedra, faces with four equivalent Mg(4)Mg12 cuboctahedra, and faces with six equivalent Mg(7)Mg11Sb cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(7), four equivalent Mg(4), and four equivalent Mg(5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Nb(1)Mg10Sb2 cuboctahedra, corners with six equivalent Mg(2)Mg12 cuboctahedra, corners with eight equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with four equivalent Mg(7)Mg11Sb cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with eight equivalent Mg(5)Mg10NbSb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Sb(1)Mg10Nb2 cuboctahedra, faces with four equivalent Mg(5)Mg10NbSb cuboctahedra, faces with four equivalent Mg(4)Mg12 cuboctahedra, and faces with six equivalent Mg(6)Mg11Nb cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), two equivalent Nb(1), and two equivalent Sb(1) atoms to form distorted MgMg8Nb2Sb2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra, corners with four equivalent Mg(2)Mg12 cuboctahedra, corners with four equivalent Mg(4)Mg12 cuboctahedra, corners with six equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with two equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with two equivalent Nb(1)Mg10Sb2 cuboctahedra, edges with two equivalent Sb(1)Mg10Nb2 cuboctahedra, edges with four equivalent Mg(5)Mg10NbSb cuboctahedra, edges with four equivalent Mg(6)Mg11Nb cuboctahedra, edges with four equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, faces with two equivalent Nb(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Mg10Nb2 cuboctahedra, and faces with eight equivalent Mg(5)Mg10NbSb cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), two equivalent Mg(6), and two equivalent Mg(7) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, corners with four equivalent Nb(1)Mg10Sb2 cuboctahedra, corners with four equivalent Sb(1)Mg10Nb2 cuboctahedra, corners with six equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with two equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(5)Mg10NbSb cuboctahedra, edges with four equivalent Mg(6)Mg11Nb cuboctahedra, edges with four equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, and faces with eight equivalent Mg(5)Mg10NbSb cuboctahedra. In the fifth Mg site, Mg(5) is bonded to one Mg(1), one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), one Nb(1), and one Sb(1) atom to form distorted MgMg10NbSb cuboctahedra that share corners with four equivalent Mg(6)Mg11Nb cuboctahedra, corners with four equivalent Mg(7)Mg11Sb cuboctahedra, corners with ten equivalent Mg(5)Mg10NbSb cuboctahedra, edges with two equivalent Mg(5)Mg10NbSb cuboctahedra, edges with two equivalent Mg(6)Mg11Nb cuboctahedra, edges with two equivalent Mg(7)Mg11Sb cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with two equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with two equivalent Nb(1)Mg10Sb2 cuboctahedra, edges with two equivalent Sb(1)Mg10Nb2 cuboctahedra,  a faceface with one Mg(1)Mg12 cuboctahedra,  a faceface with one Mg(2)Mg12 cuboctahedra,  a faceface with one Nb(1)Mg10Sb2 cuboctahedra,  a faceface with one Sb(1)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with four equivalent Mg(5)Mg10NbSb cuboctahedra, faces with four equivalent Mg(4)Mg12 cuboctahedra, and faces with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra. In the sixth Mg site, Mg(6) is bonded to one Mg(1), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(7), four equivalent Mg(5), and one Nb(1) atom to form distorted MgMg11Nb cuboctahedra that share corners with four equivalent Mg(7)Mg11Sb cuboctahedra, corners with six equivalent Mg(6)Mg11Nb cuboctahedra, corners with eight equivalent Mg(5)Mg10NbSb cuboctahedra, edges with two equivalent Mg(7)Mg11Sb cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with two equivalent Nb(1)Mg10Sb2 cuboctahedra, edges with four equivalent Mg(5)Mg10NbSb cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra,  a faceface with one Mg(1)Mg12 cuboctahedra,  a faceface with one Nb(1)Mg10Sb2 cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, faces with three equivalent Mg(2)Mg12 cuboctahedra, faces with three equivalent Sb(1)Mg10Nb2 cuboctahedra, and faces with four equivalent Mg(5)Mg10NbSb cuboctahedra. In the seventh Mg site, Mg(7) is bonded to one Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(6), four equivalent Mg(5), and one Sb(1) atom to form distorted MgMg11Sb cuboctahedra that share corners with four equivalent Mg(6)Mg11Nb cuboctahedra, corners with six equivalent Mg(7)Mg11Sb cuboctahedra, corners with eight equivalent Mg(5)Mg10NbSb cuboctahedra, edges with two equivalent Mg(6)Mg11Nb cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with two equivalent Sb(1)Mg10Nb2 cuboctahedra, edges with four equivalent Mg(5)Mg10NbSb cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra,  a faceface with one Mg(2)Mg12 cuboctahedra,  a faceface with one Sb(1)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, faces with three equivalent Mg(1)Mg12 cuboctahedra, faces with three equivalent Nb(1)Mg10Sb2 cuboctahedra, and faces with four equivalent Mg(5)Mg10NbSb cuboctahedra. Nb(1) is bonded to two equivalent Mg(6), four equivalent Mg(3), four equivalent Mg(5), and two equivalent Sb(1) atoms to form NbMg10Sb2 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra, corners with six equivalent Nb(1)Mg10Sb2 cuboctahedra, corners with eight equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Sb(1)Mg10Nb2 cuboctahedra, edges with four equivalent Mg(6)Mg11Nb cuboctahedra, edges with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with eight equivalent Mg(5)Mg10NbSb cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Sb(1)Mg10Nb2 cuboctahedra, faces with four equivalent Mg(5)Mg10NbSb cuboctahedra, faces with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, and faces with six equivalent Mg(7)Mg11Sb cuboctahedra. Sb(1) is bonded to two equivalent Mg(7), four equivalent Mg(3), four equivalent Mg(5), and two equivalent Nb(1) atoms to form SbMg10Nb2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra, corners with six equivalent Sb(1)Mg10Nb2 cuboctahedra, corners with eight equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Nb(1)Mg10Sb2 cuboctahedra, edges with four equivalent Mg(7)Mg11Sb cuboctahedra, edges with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with eight equivalent Mg(5)Mg10NbSb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Nb(1)Mg10Sb2 cuboctahedra, faces with four equivalent Mg(5)Mg10NbSb cuboctahedra, faces with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, and faces with six equivalent Mg(6)Mg11Nb cuboctahedra.
Mg14NbSb crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2), two equivalent Mg(6), four equivalent Mg(4), and four equivalent Mg(5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Sb(1)Mg10Nb2 cuboctahedra, corners with six equivalent Mg(1)Mg12 cuboctahedra, corners with eight equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with four equivalent Mg(6)Mg11Nb cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with eight equivalent Mg(5)Mg10NbSb cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Nb(1)Mg10Sb2 cuboctahedra, faces with four equivalent Mg(5)Mg10NbSb cuboctahedra, faces with four equivalent Mg(4)Mg12 cuboctahedra, and faces with six equivalent Mg(7)Mg11Sb cuboctahedra. Both Mg(1)-Mg(2) bond lengths are 3.12 Å. Both Mg(1)-Mg(6) bond lengths are 3.16 Å. All Mg(1)-Mg(4) bond lengths are 3.17 Å. All Mg(1)-Mg(5) bond lengths are 3.14 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(7), four equivalent Mg(4), and four equivalent Mg(5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Nb(1)Mg10Sb2 cuboctahedra, corners with six equivalent Mg(2)Mg12 cuboctahedra, corners with eight equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with four equivalent Mg(7)Mg11Sb cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with eight equivalent Mg(5)Mg10NbSb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Sb(1)Mg10Nb2 cuboctahedra, faces with four equivalent Mg(5)Mg10NbSb cuboctahedra, faces with four equivalent Mg(4)Mg12 cuboctahedra, and faces with six equivalent Mg(6)Mg11Nb cuboctahedra. Both Mg(2)-Mg(7) bond lengths are 3.15 Å. There are two shorter (3.16 Å) and two longer (3.17 Å) Mg(2)-Mg(4) bond lengths. All Mg(2)-Mg(5) bond lengths are 3.17 Å. In the third Mg site, Mg(3) is bonded to two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), two equivalent Nb(1), and two equivalent Sb(1) atoms to form distorted MgMg8Nb2Sb2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra, corners with four equivalent Mg(2)Mg12 cuboctahedra, corners with four equivalent Mg(4)Mg12 cuboctahedra, corners with six equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with two equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with two equivalent Nb(1)Mg10Sb2 cuboctahedra, edges with two equivalent Sb(1)Mg10Nb2 cuboctahedra, edges with four equivalent Mg(5)Mg10NbSb cuboctahedra, edges with four equivalent Mg(6)Mg11Nb cuboctahedra, edges with four equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, faces with two equivalent Nb(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Mg10Nb2 cuboctahedra, and faces with eight equivalent Mg(5)Mg10NbSb cuboctahedra. There is one shorter (3.10 Å) and one longer (3.14 Å) Mg(3)-Mg(3) bond length. Both Mg(3)-Mg(5) bond lengths are 3.15 Å. Both Mg(3)-Mg(6) bond lengths are 3.12 Å. Both Mg(3)-Mg(7) bond lengths are 3.16 Å. There is one shorter (3.16 Å) and one longer (3.17 Å) Mg(3)-Nb(1) bond length. There is one shorter (3.14 Å) and one longer (3.20 Å) Mg(3)-Sb(1) bond length. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), two equivalent Mg(6), and two equivalent Mg(7) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, corners with four equivalent Nb(1)Mg10Sb2 cuboctahedra, corners with four equivalent Sb(1)Mg10Nb2 cuboctahedra, corners with six equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with two equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(5)Mg10NbSb cuboctahedra, edges with four equivalent Mg(6)Mg11Nb cuboctahedra, edges with four equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, and faces with eight equivalent Mg(5)Mg10NbSb cuboctahedra. There is one shorter (3.11 Å) and one longer (3.12 Å) Mg(4)-Mg(4) bond length. Both Mg(4)-Mg(5) bond lengths are 3.18 Å. Both Mg(4)-Mg(6) bond lengths are 3.18 Å. Both Mg(4)-Mg(7) bond lengths are 3.12 Å. In the fifth Mg site, Mg(5) is bonded to one Mg(1), one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), one Nb(1), and one Sb(1) atom to form distorted MgMg10NbSb cuboctahedra that share corners with four equivalent Mg(6)Mg11Nb cuboctahedra, corners with four equivalent Mg(7)Mg11Sb cuboctahedra, corners with ten equivalent Mg(5)Mg10NbSb cuboctahedra, edges with two equivalent Mg(5)Mg10NbSb cuboctahedra, edges with two equivalent Mg(6)Mg11Nb cuboctahedra, edges with two equivalent Mg(7)Mg11Sb cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with two equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with two equivalent Nb(1)Mg10Sb2 cuboctahedra, edges with two equivalent Sb(1)Mg10Nb2 cuboctahedra,  a faceface with one Mg(1)Mg12 cuboctahedra,  a faceface with one Mg(2)Mg12 cuboctahedra,  a faceface with one Nb(1)Mg10Sb2 cuboctahedra,  a faceface with one Sb(1)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with four equivalent Mg(5)Mg10NbSb cuboctahedra, faces with four equivalent Mg(4)Mg12 cuboctahedra, and faces with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra. There is one shorter (3.05 Å) and one longer (3.18 Å) Mg(5)-Mg(5) bond length. There is one shorter (3.11 Å) and one longer (3.22 Å) Mg(5)-Mg(6) bond length. There is one shorter (3.15 Å) and one longer (3.19 Å) Mg(5)-Mg(7) bond length. The Mg(5)-Nb(1) bond length is 3.10 Å. The Mg(5)-Sb(1) bond length is 3.15 Å. In the sixth Mg site, Mg(6) is bonded to one Mg(1), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(7), four equivalent Mg(5), and one Nb(1) atom to form distorted MgMg11Nb cuboctahedra that share corners with four equivalent Mg(7)Mg11Sb cuboctahedra, corners with six equivalent Mg(6)Mg11Nb cuboctahedra, corners with eight equivalent Mg(5)Mg10NbSb cuboctahedra, edges with two equivalent Mg(7)Mg11Sb cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with two equivalent Nb(1)Mg10Sb2 cuboctahedra, edges with four equivalent Mg(5)Mg10NbSb cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra,  a faceface with one Mg(1)Mg12 cuboctahedra,  a faceface with one Nb(1)Mg10Sb2 cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, faces with three equivalent Mg(2)Mg12 cuboctahedra, faces with three equivalent Sb(1)Mg10Nb2 cuboctahedra, and faces with four equivalent Mg(5)Mg10NbSb cuboctahedra. Both Mg(6)-Mg(7) bond lengths are 3.12 Å. The Mg(6)-Nb(1) bond length is 3.13 Å. In the seventh Mg site, Mg(7) is bonded to one Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(6), four equivalent Mg(5), and one Sb(1) atom to form distorted MgMg11Sb cuboctahedra that share corners with four equivalent Mg(6)Mg11Nb cuboctahedra, corners with six equivalent Mg(7)Mg11Sb cuboctahedra, corners with eight equivalent Mg(5)Mg10NbSb cuboctahedra, edges with two equivalent Mg(6)Mg11Nb cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with two equivalent Sb(1)Mg10Nb2 cuboctahedra, edges with four equivalent Mg(5)Mg10NbSb cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra,  a faceface with one Mg(2)Mg12 cuboctahedra,  a faceface with one Sb(1)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, faces with three equivalent Mg(1)Mg12 cuboctahedra, faces with three equivalent Nb(1)Mg10Sb2 cuboctahedra, and faces with four equivalent Mg(5)Mg10NbSb cuboctahedra. The Mg(7)-Sb(1) bond length is 3.17 Å. Nb(1) is bonded to two equivalent Mg(6), four equivalent Mg(3), four equivalent Mg(5), and two equivalent Sb(1) atoms to form NbMg10Sb2 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra, corners with six equivalent Nb(1)Mg10Sb2 cuboctahedra, corners with eight equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Sb(1)Mg10Nb2 cuboctahedra, edges with four equivalent Mg(6)Mg11Nb cuboctahedra, edges with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with eight equivalent Mg(5)Mg10NbSb cuboctahedra, faces with two equivalent Mg(6)Mg11Nb cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Sb(1)Mg10Nb2 cuboctahedra, faces with four equivalent Mg(5)Mg10NbSb cuboctahedra, faces with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, and faces with six equivalent Mg(7)Mg11Sb cuboctahedra. Both Nb(1)-Sb(1) bond lengths are 3.12 Å. Sb(1) is bonded to two equivalent Mg(7), four equivalent Mg(3), four equivalent Mg(5), and two equivalent Nb(1) atoms to form SbMg10Nb2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra, corners with six equivalent Sb(1)Mg10Nb2 cuboctahedra, corners with eight equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Nb(1)Mg10Sb2 cuboctahedra, edges with four equivalent Mg(7)Mg11Sb cuboctahedra, edges with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, edges with eight equivalent Mg(5)Mg10NbSb cuboctahedra, faces with two equivalent Mg(7)Mg11Sb cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Nb(1)Mg10Sb2 cuboctahedra, faces with four equivalent Mg(5)Mg10NbSb cuboctahedra, faces with four equivalent Mg(3)Mg8Nb2Sb2 cuboctahedra, and faces with six equivalent Mg(6)Mg11Nb cuboctahedra.