Mg14CoBi 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 Bi(1)Mg10Co2 cuboctahedra, corners with six equivalent Mg(1)Mg12 cuboctahedra, corners with eight equivalent Mg(5)Mg6CoBi cuboctahedra, corners with eight equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Co(1)Mg10Bi2 cuboctahedra, faces with four equivalent Mg(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 equivalent Mg(4), and four equivalent Mg(5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Mg(5)Mg6CoBi cuboctahedra, corners with four equivalent Co(1)Mg10Bi2 cuboctahedra, corners with six equivalent Mg(2)Mg12 cuboctahedra, corners with eight equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with four equivalent Mg(7)Mg11Bi cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi cuboctahedra, faces with two equivalent Mg(7)Mg11Bi cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Bi(1)Mg10Co2 cuboctahedra, faces with four equivalent Mg(4)Mg12 cuboctahedra, and faces with four equivalent Mg(5)Mg6CoBi 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 Co(1), and two equivalent Bi(1) atoms to form distorted MgMg8Co2Bi2 cuboctahedra that share corners with two equivalent Mg(5)Mg6CoBi cuboctahedra, 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)Mg8Co2Bi2 cuboctahedra, edges with two equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, edges with two equivalent Co(1)Mg10Bi2 cuboctahedra, edges with two equivalent Bi(1)Mg10Co2 cuboctahedra, edges with four equivalent Mg(7)Mg11Bi cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi cuboctahedra, faces with two equivalent Mg(7)Mg11Bi cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, faces with two equivalent Co(1)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Mg10Co2 cuboctahedra, and faces with six equivalent Mg(5)Mg6CoBi 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 two equivalent Mg(5)Mg6CoBi cuboctahedra, corners with four equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, corners with four equivalent Co(1)Mg10Bi2 cuboctahedra, corners with four equivalent Bi(1)Mg10Co2 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(7)Mg11Bi cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi 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, faces with two equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, and faces with six equivalent Mg(5)Mg6CoBi 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(7), one Co(1), and one Bi(1) atom to form distorted MgMg6CoBi cuboctahedra that share  a cornercorner with one Mg(2)Mg12 cuboctahedra,  a cornercorner with one Mg(4)Mg12 cuboctahedra,  a cornercorner with one Mg(3)Mg8Co2Bi2 cuboctahedra,  a cornercorner with one Bi(1)Mg10Co2 cuboctahedra, corners with two equivalent Mg(1)Mg12 cuboctahedra, corners with two equivalent Co(1)Mg10Bi2 cuboctahedra, corners with four equivalent Mg(7)Mg11Bi cuboctahedra, corners with eight equivalent Mg(5)Mg6CoBi cuboctahedra,  an edgeedge with one Mg(1)Mg12 cuboctahedra,  an edgeedge with one Mg(2)Mg12 cuboctahedra,  an edgeedge with one Co(1)Mg10Bi2 cuboctahedra,  an edgeedge with one Bi(1)Mg10Co2 cuboctahedra, edges with two equivalent Mg(7)Mg11Bi cuboctahedra, edges with two equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Mg(3)Mg8Co2Bi2 cuboctahedra,  a faceface with one Mg(2)Mg12 cuboctahedra,  a faceface with one Bi(1)Mg10Co2 cuboctahedra, faces with three equivalent Mg(4)Mg12 cuboctahedra, faces with three equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, and faces with four equivalent Mg(5)Mg6CoBi cuboctahedra. In the sixth Mg site, Mg(6) is bonded in a distorted single-bond geometry to one Mg(1), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(7), and one Co(1) atom. 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 Bi(1) atom to form distorted MgMg11Bi cuboctahedra that share corners with six equivalent Mg(7)Mg11Bi cuboctahedra, corners with eight equivalent Mg(5)Mg6CoBi cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with two equivalent Bi(1)Mg10Co2 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi cuboctahedra, edges with four equivalent Mg(3)Mg8Co2Bi2 cuboctahedra,  a faceface with one Mg(2)Mg12 cuboctahedra,  a faceface with one Bi(1)Mg10Co2 cuboctahedra, faces with two equivalent Mg(7)Mg11Bi cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, faces with three equivalent Mg(1)Mg12 cuboctahedra, and faces with three equivalent Co(1)Mg10Bi2 cuboctahedra. Co(1) is bonded to two equivalent Mg(6), four equivalent Mg(3), four equivalent Mg(5), and two equivalent Bi(1) atoms to form CoMg10Bi2 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra, corners with six equivalent Co(1)Mg10Bi2 cuboctahedra, corners with eight equivalent Mg(4)Mg12 cuboctahedra, corners with eight equivalent Mg(5)Mg6CoBi cuboctahedra, edges with two equivalent Bi(1)Mg10Co2 cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi cuboctahedra, edges with four equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Bi(1)Mg10Co2 cuboctahedra, faces with four equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, and faces with six equivalent Mg(7)Mg11Bi cuboctahedra. Bi(1) is bonded to two equivalent Mg(7), four equivalent Mg(3), four equivalent Mg(5), and two equivalent Co(1) atoms to form BiMg10Co2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra, corners with four equivalent Mg(5)Mg6CoBi cuboctahedra, corners with six equivalent Bi(1)Mg10Co2 cuboctahedra, corners with eight equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Co(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(7)Mg11Bi cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi cuboctahedra, edges with four equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, faces with two equivalent Mg(7)Mg11Bi cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Co(1)Mg10Bi2 cuboctahedra, faces with four equivalent Mg(5)Mg6CoBi cuboctahedra, and faces with four equivalent Mg(3)Mg8Co2Bi2 cuboctahedra.
Mg14CoBi 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 Bi(1)Mg10Co2 cuboctahedra, corners with six equivalent Mg(1)Mg12 cuboctahedra, corners with eight equivalent Mg(5)Mg6CoBi cuboctahedra, corners with eight equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Co(1)Mg10Bi2 cuboctahedra, faces with four equivalent Mg(4)Mg12 cuboctahedra, and faces with six equivalent Mg(7)Mg11Bi cuboctahedra. Both Mg(1)-Mg(2) bond lengths are 3.15 Å. Both Mg(1)-Mg(6) bond lengths are 3.17 Å. There are two shorter (3.13 Å) and two longer (3.15 Å) Mg(1)-Mg(4) bond lengths. All Mg(1)-Mg(5) bond lengths are 3.15 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 Mg(5)Mg6CoBi cuboctahedra, corners with four equivalent Co(1)Mg10Bi2 cuboctahedra, corners with six equivalent Mg(2)Mg12 cuboctahedra, corners with eight equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, edges with two equivalent Mg(1)Mg12 cuboctahedra, edges with four equivalent Mg(7)Mg11Bi cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi cuboctahedra, faces with two equivalent Mg(7)Mg11Bi cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Bi(1)Mg10Co2 cuboctahedra, faces with four equivalent Mg(4)Mg12 cuboctahedra, and faces with four equivalent Mg(5)Mg6CoBi cuboctahedra. Both Mg(2)-Mg(7) bond lengths are 3.08 Å. There are two shorter (3.12 Å) and two longer (3.16 Å) Mg(2)-Mg(4) bond lengths. All Mg(2)-Mg(5) bond lengths are 3.22 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 Co(1), and two equivalent Bi(1) atoms to form distorted MgMg8Co2Bi2 cuboctahedra that share corners with two equivalent Mg(5)Mg6CoBi cuboctahedra, 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)Mg8Co2Bi2 cuboctahedra, edges with two equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, edges with two equivalent Co(1)Mg10Bi2 cuboctahedra, edges with two equivalent Bi(1)Mg10Co2 cuboctahedra, edges with four equivalent Mg(7)Mg11Bi cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi cuboctahedra, faces with two equivalent Mg(7)Mg11Bi cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, faces with two equivalent Co(1)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Mg10Co2 cuboctahedra, and faces with six equivalent Mg(5)Mg6CoBi cuboctahedra. There is one shorter (3.14 Å) and one longer (3.17 Å) Mg(3)-Mg(3) bond length. Both Mg(3)-Mg(5) bond lengths are 3.07 Å. Both Mg(3)-Mg(6) bond lengths are 3.05 Å. Both Mg(3)-Mg(7) bond lengths are 3.17 Å. There is one shorter (3.12 Å) and one longer (3.16 Å) Mg(3)-Co(1) bond length. There is one shorter (3.09 Å) and one longer (3.19 Å) Mg(3)-Bi(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 two equivalent Mg(5)Mg6CoBi cuboctahedra, corners with four equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, corners with four equivalent Co(1)Mg10Bi2 cuboctahedra, corners with four equivalent Bi(1)Mg10Co2 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(7)Mg11Bi cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi 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, faces with two equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, and faces with six equivalent Mg(5)Mg6CoBi cuboctahedra. There is one shorter (3.12 Å) and one longer (3.19 Å) Mg(4)-Mg(4) bond length. Both Mg(4)-Mg(5) bond lengths are 3.19 Å. Both Mg(4)-Mg(6) bond lengths are 3.22 Å. Both Mg(4)-Mg(7) bond lengths are 3.07 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(7), one Co(1), and one Bi(1) atom to form distorted MgMg6CoBi cuboctahedra that share  a cornercorner with one Mg(2)Mg12 cuboctahedra,  a cornercorner with one Mg(4)Mg12 cuboctahedra,  a cornercorner with one Mg(3)Mg8Co2Bi2 cuboctahedra,  a cornercorner with one Bi(1)Mg10Co2 cuboctahedra, corners with two equivalent Mg(1)Mg12 cuboctahedra, corners with two equivalent Co(1)Mg10Bi2 cuboctahedra, corners with four equivalent Mg(7)Mg11Bi cuboctahedra, corners with eight equivalent Mg(5)Mg6CoBi cuboctahedra,  an edgeedge with one Mg(1)Mg12 cuboctahedra,  an edgeedge with one Mg(2)Mg12 cuboctahedra,  an edgeedge with one Co(1)Mg10Bi2 cuboctahedra,  an edgeedge with one Bi(1)Mg10Co2 cuboctahedra, edges with two equivalent Mg(7)Mg11Bi cuboctahedra, edges with two equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Mg(3)Mg8Co2Bi2 cuboctahedra,  a faceface with one Mg(2)Mg12 cuboctahedra,  a faceface with one Bi(1)Mg10Co2 cuboctahedra, faces with three equivalent Mg(4)Mg12 cuboctahedra, faces with three equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, and faces with four equivalent Mg(5)Mg6CoBi cuboctahedra. There is one shorter (3.10 Å) and one longer (3.18 Å) Mg(5)-Mg(7) bond length. The Mg(5)-Co(1) bond length is 3.02 Å. The Mg(5)-Bi(1) bond length is 3.10 Å. In the sixth Mg site, Mg(6) is bonded in a distorted single-bond geometry to one Mg(1), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(7), and one Co(1) atom. Both Mg(6)-Mg(7) bond lengths are 3.16 Å. The Mg(6)-Co(1) bond length is 2.99 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 Bi(1) atom to form distorted MgMg11Bi cuboctahedra that share corners with six equivalent Mg(7)Mg11Bi cuboctahedra, corners with eight equivalent Mg(5)Mg6CoBi cuboctahedra, edges with two equivalent Mg(2)Mg12 cuboctahedra, edges with two equivalent Bi(1)Mg10Co2 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi cuboctahedra, edges with four equivalent Mg(3)Mg8Co2Bi2 cuboctahedra,  a faceface with one Mg(2)Mg12 cuboctahedra,  a faceface with one Bi(1)Mg10Co2 cuboctahedra, faces with two equivalent Mg(7)Mg11Bi cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, faces with three equivalent Mg(1)Mg12 cuboctahedra, and faces with three equivalent Co(1)Mg10Bi2 cuboctahedra. The Mg(7)-Bi(1) bond length is 3.17 Å. Co(1) is bonded to two equivalent Mg(6), four equivalent Mg(3), four equivalent Mg(5), and two equivalent Bi(1) atoms to form CoMg10Bi2 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra, corners with six equivalent Co(1)Mg10Bi2 cuboctahedra, corners with eight equivalent Mg(4)Mg12 cuboctahedra, corners with eight equivalent Mg(5)Mg6CoBi cuboctahedra, edges with two equivalent Bi(1)Mg10Co2 cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi cuboctahedra, edges with four equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Bi(1)Mg10Co2 cuboctahedra, faces with four equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, and faces with six equivalent Mg(7)Mg11Bi cuboctahedra. Both Co(1)-Bi(1) bond lengths are 3.15 Å. Bi(1) is bonded to two equivalent Mg(7), four equivalent Mg(3), four equivalent Mg(5), and two equivalent Co(1) atoms to form BiMg10Co2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra, corners with four equivalent Mg(5)Mg6CoBi cuboctahedra, corners with six equivalent Bi(1)Mg10Co2 cuboctahedra, corners with eight equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Co(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(7)Mg11Bi cuboctahedra, edges with four equivalent Mg(5)Mg6CoBi cuboctahedra, edges with four equivalent Mg(3)Mg8Co2Bi2 cuboctahedra, faces with two equivalent Mg(7)Mg11Bi cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Co(1)Mg10Bi2 cuboctahedra, faces with four equivalent Mg(5)Mg6CoBi cuboctahedra, and faces with four equivalent Mg(3)Mg8Co2Bi2 cuboctahedra.