Mg14BiSb crystallizes in the orthorhombic Amm2 space group. There are nine inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2); two equivalent Mg(6); four Mg(4,4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Bi(1)Mg10Sb2 cuboctahedra; corners with six equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with four Mg(4,4)Mg12 cuboctahedra; edges with eight Mg(5,5)Mg10BiSb cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Sb(1)Mg10Bi2 cuboctahedra; faces with four Mg(5,5)Mg10BiSb cuboctahedra; faces with four Mg(4,4)Mg12 cuboctahedra; and faces with six equivalent Mg(7)Mg11Bi cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1); two equivalent Mg(7); four Mg(4,4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra; corners with six equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with four equivalent Mg(7)Mg11Bi cuboctahedra; edges with four Mg(4,4)Mg12 cuboctahedra; edges with eight Mg(5,5)Mg10BiSb cuboctahedra; faces with two equivalent Mg(7)Mg11Bi cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra; faces with four Mg(5,5)Mg10BiSb cuboctahedra; and faces with four Mg(4,4)Mg12 cuboctahedra. In the third Mg site, Mg(3) is bonded in a 4-coordinate geometry to two equivalent Mg(5), two equivalent Mg(7), two equivalent Bi(1), and two equivalent Sb(1) atoms. 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 Bi(1)Mg10Sb2 cuboctahedra; corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra; corners with six Mg(4,4)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)Mg10BiSb cuboctahedra; edges with four equivalent Mg(7)Mg11Bi cuboctahedra; faces with two equivalent Mg(7)Mg11Bi 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; and faces with eight Mg(5,5)Mg10BiSb 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 Bi(1), and one Sb(1) atom to form distorted MgMg10BiSb cuboctahedra that share corners with four equivalent Mg(7)Mg11Bi cuboctahedra; corners with ten equivalent Mg(5)Mg10BiSb cuboctahedra; edges with two equivalent Mg(5)Mg10BiSb cuboctahedra; edges with two equivalent Mg(7)Mg11Bi 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 Bi(1)Mg10Sb2 cuboctahedra; edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Bi(1)Mg10Sb2 cuboctahedra;  a faceface with one Sb(1)Mg10Bi2 cuboctahedra; faces with two equivalent Mg(7)Mg11Bi cuboctahedra; faces with four equivalent Mg(5)Mg10BiSb cuboctahedra; and faces with four Mg(4,4)Mg12 cuboctahedra. In the sixth 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 Bi(1), and one Sb(1) atom to form distorted MgMg10BiSb cuboctahedra that share corners with four equivalent Mg(7)Mg11Bi cuboctahedra; corners with ten Mg(5,5)Mg10BiSb cuboctahedra; edges with two equivalent Mg(5)Mg10BiSb cuboctahedra; edges with two equivalent Mg(7)Mg11Bi 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 Bi(1)Mg10Sb2 cuboctahedra; edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Bi(1)Mg10Sb2 cuboctahedra;  a faceface with one Sb(1)Mg10Bi2 cuboctahedra; faces with two equivalent Mg(7)Mg11Bi cuboctahedra; faces with four Mg(5,5)Mg10BiSb cuboctahedra; and faces with four Mg(4,4)Mg12 cuboctahedra. In the seventh Mg site, Mg(6) is bonded in a distorted single-bond geometry to one Mg(1); two Mg(4,4); two equivalent Mg(7); four Mg(5,5); and one Sb(1) atom. In the eighth Mg site, Mg(7) is bonded to one Mg(2); two equivalent Mg(3); two Mg(4,4); two equivalent Mg(6); four Mg(5,5); and one Bi(1) atom to form distorted MgMg11Bi cuboctahedra that share corners with six equivalent Mg(7)Mg11Bi cuboctahedra; corners with eight Mg(5,5)Mg10BiSb cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Bi(1)Mg10Sb2 cuboctahedra; edges with four Mg(5,5)Mg10BiSb cuboctahedra; edges with four Mg(4,4)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Bi(1)Mg10Sb2 cuboctahedra; faces with two equivalent Mg(7)Mg11Bi cuboctahedra; faces with two Mg(4,4)Mg12 cuboctahedra; faces with three equivalent Mg(1)Mg12 cuboctahedra; faces with three equivalent Sb(1)Mg10Bi2 cuboctahedra; and faces with four Mg(5,5)Mg10BiSb cuboctahedra. In the ninth 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 Bi(1)Mg10Sb2 cuboctahedra; corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra; corners with six Mg(4,4)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)Mg10BiSb cuboctahedra; edges with four equivalent Mg(7)Mg11Bi cuboctahedra; faces with two equivalent Mg(7)Mg11Bi 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; and faces with eight Mg(5,5)Mg10BiSb cuboctahedra. Bi(1) is bonded to two equivalent Mg(7); four equivalent Mg(3); four Mg(5,5); and two equivalent Sb(1) atoms to form distorted BiMg10Sb2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with six equivalent Bi(1)Mg10Sb2 cuboctahedra; corners with eight Mg(4,4)Mg12 cuboctahedra; edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra; edges with four equivalent Mg(7)Mg11Bi cuboctahedra; edges with eight Mg(5,5)Mg10BiSb cuboctahedra; faces with two equivalent Mg(7)Mg11Bi cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Sb(1)Mg10Bi2 cuboctahedra; and faces with four Mg(5,5)Mg10BiSb cuboctahedra. Sb(1) is bonded to two equivalent Mg(6); four equivalent Mg(3); four Mg(5,5); and two equivalent Bi(1) atoms to form distorted SbMg10Bi2 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra; corners with six equivalent Sb(1)Mg10Bi2 cuboctahedra; corners with eight Mg(4,4)Mg12 cuboctahedra; edges with two equivalent Bi(1)Mg10Sb2 cuboctahedra; edges with eight Mg(5,5)Mg10BiSb cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra; faces with four Mg(5,5)Mg10BiSb cuboctahedra; and faces with six equivalent Mg(7)Mg11Bi cuboctahedra.
Mg14BiSb crystallizes in the orthorhombic Amm2 space group. There are nine inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2); two equivalent Mg(6); four Mg(4,4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Bi(1)Mg10Sb2 cuboctahedra; corners with six equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with four Mg(4,4)Mg12 cuboctahedra; edges with eight Mg(5,5)Mg10BiSb cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Sb(1)Mg10Bi2 cuboctahedra; faces with four Mg(5,5)Mg10BiSb cuboctahedra; faces with four Mg(4,4)Mg12 cuboctahedra; and faces with six equivalent Mg(7)Mg11Bi cuboctahedra. Both Mg(1)-Mg(2) bond lengths are 3.32 Å. Both Mg(1)-Mg(6) bond lengths are 3.18 Å. All Mg(1)-Mg(4,4) bond lengths are 3.19 Å. All Mg(1)-Mg(5,5) bond lengths are 3.16 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1); two equivalent Mg(7); four Mg(4,4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra; corners with six equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with four equivalent Mg(7)Mg11Bi cuboctahedra; edges with four Mg(4,4)Mg12 cuboctahedra; edges with eight Mg(5,5)Mg10BiSb cuboctahedra; faces with two equivalent Mg(7)Mg11Bi cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra; faces with four Mg(5,5)Mg10BiSb cuboctahedra; and faces with four Mg(4,4)Mg12 cuboctahedra. Both Mg(2)-Mg(7) bond lengths are 3.17 Å. There are two shorter (3.19 Å) and two longer (3.20 Å) Mg(2)-Mg(4,4) bond lengths. All Mg(2)-Mg(5,5) bond lengths are 3.18 Å. In the third Mg site, Mg(3) is bonded in a 4-coordinate geometry to two equivalent Mg(5), two equivalent Mg(7), two equivalent Bi(1), and two equivalent Sb(1) atoms. Both Mg(3)-Mg(5) bond lengths are 3.23 Å. Both Mg(3)-Mg(7) bond lengths are 3.26 Å. There is one shorter (3.18 Å) and one longer (3.21 Å) Mg(3)-Bi(1) bond length. There is one shorter (3.16 Å) and one longer (3.22 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 Bi(1)Mg10Sb2 cuboctahedra; corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra; corners with six Mg(4,4)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)Mg10BiSb cuboctahedra; edges with four equivalent Mg(7)Mg11Bi cuboctahedra; faces with two equivalent Mg(7)Mg11Bi 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; and faces with eight Mg(5,5)Mg10BiSb cuboctahedra. There is one shorter (3.31 Å) and one longer (3.33 Å) Mg(4)-Mg(4) bond length. Both Mg(4)-Mg(5) bond lengths are 3.13 Å. Both Mg(4)-Mg(6) bond lengths are 3.20 Å. Both Mg(4)-Mg(7) bond lengths are 3.17 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 Bi(1), and one Sb(1) atom to form distorted MgMg10BiSb cuboctahedra that share corners with four equivalent Mg(7)Mg11Bi cuboctahedra; corners with ten equivalent Mg(5)Mg10BiSb cuboctahedra; edges with two equivalent Mg(5)Mg10BiSb cuboctahedra; edges with two equivalent Mg(7)Mg11Bi 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 Bi(1)Mg10Sb2 cuboctahedra; edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Bi(1)Mg10Sb2 cuboctahedra;  a faceface with one Sb(1)Mg10Bi2 cuboctahedra; faces with two equivalent Mg(7)Mg11Bi cuboctahedra; faces with four equivalent Mg(5)Mg10BiSb cuboctahedra; and faces with four Mg(4,4)Mg12 cuboctahedra. There is one shorter (3.29 Å) and one longer (3.35 Å) Mg(5)-Mg(5) bond length. There is one shorter (3.18 Å) and one longer (3.21 Å) Mg(5)-Mg(6) bond length. There is one shorter (3.15 Å) and one longer (3.24 Å) Mg(5)-Mg(7) bond length. The Mg(5)-Bi(1) bond length is 3.29 Å. The Mg(5)-Sb(1) bond length is 3.29 Å. In the sixth 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 Bi(1), and one Sb(1) atom to form distorted MgMg10BiSb cuboctahedra that share corners with four equivalent Mg(7)Mg11Bi cuboctahedra; corners with ten Mg(5,5)Mg10BiSb cuboctahedra; edges with two equivalent Mg(5)Mg10BiSb cuboctahedra; edges with two equivalent Mg(7)Mg11Bi 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 Bi(1)Mg10Sb2 cuboctahedra; edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Bi(1)Mg10Sb2 cuboctahedra;  a faceface with one Sb(1)Mg10Bi2 cuboctahedra; faces with two equivalent Mg(7)Mg11Bi cuboctahedra; faces with four Mg(5,5)Mg10BiSb cuboctahedra; and faces with four Mg(4,4)Mg12 cuboctahedra. The Mg(5)-Mg(3) bond length is 3.23 Å. The Mg(5)-Mg(4) bond length is 3.13 Å. There is one shorter (3.29 Å) and one longer (3.35 Å) Mg(5)-Mg(5) bond length. There is one shorter (3.18 Å) and one longer (3.21 Å) Mg(5)-Mg(6) bond length. There is one shorter (3.15 Å) and one longer (3.24 Å) Mg(5)-Mg(7) bond length. The Mg(5)-Bi(1) bond length is 3.29 Å. The Mg(5)-Sb(1) bond length is 3.29 Å. In the seventh Mg site, Mg(6) is bonded in a distorted single-bond geometry to one Mg(1); two Mg(4,4); two equivalent Mg(7); four Mg(5,5); and one Sb(1) atom. The Mg(6)-Mg(4) bond length is 3.20 Å. Both Mg(6)-Mg(7) bond lengths are 3.32 Å. The Mg(6)-Sb(1) bond length is 3.19 Å. In the eighth Mg site, Mg(7) is bonded to one Mg(2); two equivalent Mg(3); two Mg(4,4); two equivalent Mg(6); four Mg(5,5); and one Bi(1) atom to form distorted MgMg11Bi cuboctahedra that share corners with six equivalent Mg(7)Mg11Bi cuboctahedra; corners with eight Mg(5,5)Mg10BiSb cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Bi(1)Mg10Sb2 cuboctahedra; edges with four Mg(5,5)Mg10BiSb cuboctahedra; edges with four Mg(4,4)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Bi(1)Mg10Sb2 cuboctahedra; faces with two equivalent Mg(7)Mg11Bi cuboctahedra; faces with two Mg(4,4)Mg12 cuboctahedra; faces with three equivalent Mg(1)Mg12 cuboctahedra; faces with three equivalent Sb(1)Mg10Bi2 cuboctahedra; and faces with four Mg(5,5)Mg10BiSb cuboctahedra. The Mg(7)-Mg(4) bond length is 3.17 Å. The Mg(7)-Bi(1) bond length is 3.24 Å. In the ninth 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 Bi(1)Mg10Sb2 cuboctahedra; corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra; corners with six Mg(4,4)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)Mg10BiSb cuboctahedra; edges with four equivalent Mg(7)Mg11Bi cuboctahedra; faces with two equivalent Mg(7)Mg11Bi 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; and faces with eight Mg(5,5)Mg10BiSb cuboctahedra. Both Mg(4)-Mg(5) bond lengths are 3.13 Å. Bi(1) is bonded to two equivalent Mg(7); four equivalent Mg(3); four Mg(5,5); and two equivalent Sb(1) atoms to form distorted BiMg10Sb2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with six equivalent Bi(1)Mg10Sb2 cuboctahedra; corners with eight Mg(4,4)Mg12 cuboctahedra; edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra; edges with four equivalent Mg(7)Mg11Bi cuboctahedra; edges with eight Mg(5,5)Mg10BiSb cuboctahedra; faces with two equivalent Mg(7)Mg11Bi cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Sb(1)Mg10Bi2 cuboctahedra; and faces with four Mg(5,5)Mg10BiSb cuboctahedra. Both Bi(1)-Sb(1) bond lengths are 3.32 Å. Sb(1) is bonded to two equivalent Mg(6); four equivalent Mg(3); four Mg(5,5); and two equivalent Bi(1) atoms to form distorted SbMg10Bi2 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra; corners with six equivalent Sb(1)Mg10Bi2 cuboctahedra; corners with eight Mg(4,4)Mg12 cuboctahedra; edges with two equivalent Bi(1)Mg10Sb2 cuboctahedra; edges with eight Mg(5,5)Mg10BiSb cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra; faces with four Mg(5,5)Mg10BiSb cuboctahedra; and faces with six equivalent Mg(7)Mg11Bi cuboctahedra.