Mg14SiBi crystallizes in the orthorhombic Amm2 space group. There are eleven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2); two equivalent Mg(6); four Mg(4,4,4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Bi(1)Mg10Si2 cuboctahedra; corners with six equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with four Mg(4,4,4)Mg12 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Si(1)Mg10Bi2 cuboctahedra; and faces with four Mg(4,4,4)Mg12 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1); two equivalent Mg(7); four Mg(4,4,4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Si(1)Mg10Bi2 cuboctahedra; corners with six equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with four Mg(4,4,4)Mg12 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Bi(1)Mg10Si2 cuboctahedra; and faces with four Mg(4,4,4)Mg12 cuboctahedra. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Mg(3); two Mg(5,5); two equivalent Mg(6); two equivalent Mg(7); two equivalent Si(1); and two equivalent Bi(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 Mg(5,5); two equivalent Mg(6); and two equivalent Mg(7) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Si(1)Mg10Bi2 cuboctahedra; corners with four equivalent Bi(1)Mg10Si2 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; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; and faces with two equivalent Mg(4)Mg12 cuboctahedra. In the fifth Mg site, Mg(5) is bonded in a 12-coordinate geometry 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 Si(1), and one Bi(1) atom. In the sixth Mg site, Mg(5) is bonded in a 12-coordinate geometry 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 Si(1), and one Bi(1) atom. In the seventh Mg site, Mg(5) is bonded in a 12-coordinate geometry 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 Si(1), and one Bi(1) atom. In the eighth Mg site, Mg(6) is bonded in a distorted single-bond geometry to one Mg(1); two equivalent Mg(3); two Mg(4,4); four Mg(5,5); and one Si(1) atom. In the ninth Mg site, Mg(7) is bonded in a distorted single-bond geometry to one Mg(2); two equivalent Mg(3); two Mg(4,4); four Mg(5,5); and one Bi(1) atom. In the tenth 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 Si(1)Mg10Bi2 cuboctahedra; corners with four equivalent Bi(1)Mg10Si2 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; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; and faces with two equivalent Mg(4)Mg12 cuboctahedra. In the eleventh 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 Si(1)Mg10Bi2 cuboctahedra; corners with four equivalent Bi(1)Mg10Si2 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; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; and faces with two equivalent Mg(4)Mg12 cuboctahedra. Si(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 SiMg10Bi2 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra; corners with six equivalent Si(1)Mg10Bi2 cuboctahedra; corners with eight Mg(4,4,4)Mg12 cuboctahedra; edges with two equivalent Bi(1)Mg10Si2 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; and faces with two equivalent Bi(1)Mg10Si2 cuboctahedra. Bi(1) is bonded to two equivalent Mg(7); four equivalent Mg(3); four Mg(5,5); and two equivalent Si(1) atoms to form distorted BiMg10Si2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with six equivalent Bi(1)Mg10Si2 cuboctahedra; corners with eight Mg(4,4,4)Mg12 cuboctahedra; edges with two equivalent Si(1)Mg10Bi2 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; and faces with two equivalent Si(1)Mg10Bi2 cuboctahedra.
Mg14SiBi crystallizes in the orthorhombic Amm2 space group. There are eleven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2); two equivalent Mg(6); four Mg(4,4,4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Bi(1)Mg10Si2 cuboctahedra; corners with six equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with four Mg(4,4,4)Mg12 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Si(1)Mg10Bi2 cuboctahedra; and faces with four Mg(4,4,4)Mg12 cuboctahedra. Both Mg(1)-Mg(2) bond lengths are 3.28 Å. Both Mg(1)-Mg(6) bond lengths are 3.18 Å. There are two shorter (3.16 Å) and two longer (3.18 Å) Mg(1)-Mg(4,4,4) bond lengths. All Mg(1)-Mg(5,5) 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 Mg(4,4,4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Si(1)Mg10Bi2 cuboctahedra; corners with six equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with four Mg(4,4,4)Mg12 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Bi(1)Mg10Si2 cuboctahedra; and faces with four Mg(4,4,4)Mg12 cuboctahedra. Both Mg(2)-Mg(7) bond lengths are 3.13 Å. There are two shorter (3.15 Å) and two longer (3.19 Å) Mg(2)-Mg(4,4,4) bond lengths. All Mg(2)-Mg(5,5) bond lengths are 3.21 Å. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Mg(3); two Mg(5,5); two equivalent Mg(6); two equivalent Mg(7); two equivalent Si(1); and two equivalent Bi(1) atoms. There is one shorter (3.28 Å) and one longer (3.29 Å) Mg(3)-Mg(3) bond length. Both Mg(3)-Mg(5,5) bond lengths are 3.15 Å. Both Mg(3)-Mg(6) bond lengths are 3.14 Å. Both Mg(3)-Mg(7) bond lengths are 3.20 Å. There is one shorter (3.14 Å) and one longer (3.21 Å) Mg(3)-Si(1) bond length. There is one shorter (3.14 Å) and one longer (3.20 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 Mg(5,5); two equivalent Mg(6); and two equivalent Mg(7) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Si(1)Mg10Bi2 cuboctahedra; corners with four equivalent Bi(1)Mg10Si2 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; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; and faces with two equivalent Mg(4)Mg12 cuboctahedra. There is one shorter (3.27 Å) and one longer (3.30 Å) Mg(4)-Mg(4) bond length. Both Mg(4)-Mg(5,5) bond lengths are 3.16 Å. Both Mg(4)-Mg(6) bond lengths are 3.22 Å. Both Mg(4)-Mg(7) bond lengths are 3.13 Å. In the fifth Mg site, Mg(5) is bonded in a 12-coordinate geometry 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 Si(1), and one Bi(1) atom. There is one shorter (3.18 Å) and one longer (3.39 Å) Mg(5)-Mg(5) bond length. There is one shorter (3.11 Å) and one longer (3.23 Å) Mg(5)-Mg(6) bond length. There is one shorter (3.14 Å) and one longer (3.21 Å) Mg(5)-Mg(7) bond length. The Mg(5)-Si(1) bond length is 3.15 Å. The Mg(5)-Bi(1) bond length is 3.20 Å. In the sixth Mg site, Mg(5) is bonded in a 12-coordinate geometry 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 Si(1), and one Bi(1) atom. The Mg(5)-Mg(1) bond length is 3.15 Å. The Mg(5)-Mg(2) bond length is 3.21 Å. There is one shorter (3.18 Å) and one longer (3.39 Å) Mg(5)-Mg(5) bond length. There is one shorter (3.11 Å) and one longer (3.23 Å) Mg(5)-Mg(6) bond length. There is one shorter (3.14 Å) and one longer (3.21 Å) Mg(5)-Mg(7) bond length. The Mg(5)-Si(1) bond length is 3.15 Å. The Mg(5)-Bi(1) bond length is 3.20 Å. In the seventh Mg site, Mg(5) is bonded in a 12-coordinate geometry 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 Si(1), and one Bi(1) atom. The Mg(5)-Mg(3) bond length is 3.15 Å. The Mg(5)-Mg(4) bond length is 3.16 Å. There is one shorter (3.18 Å) and one longer (3.39 Å) Mg(5)-Mg(5) bond length. There is one shorter (3.11 Å) and one longer (3.23 Å) Mg(5)-Mg(6) bond length. There is one shorter (3.14 Å) and one longer (3.21 Å) Mg(5)-Mg(7) bond length. The Mg(5)-Si(1) bond length is 3.15 Å. The Mg(5)-Bi(1) bond length is 3.20 Å. In the eighth Mg site, Mg(6) is bonded in a distorted single-bond geometry to one Mg(1); two equivalent Mg(3); two Mg(4,4); four Mg(5,5); and one Si(1) atom. The Mg(6)-Mg(4) bond length is 3.22 Å. The Mg(6)-Si(1) bond length is 3.07 Å. In the ninth Mg site, Mg(7) is bonded in a distorted single-bond geometry to one Mg(2); two equivalent Mg(3); two Mg(4,4); four Mg(5,5); and one Bi(1) atom. The Mg(7)-Mg(4) bond length is 3.13 Å. The Mg(7)-Bi(1) bond length is 3.19 Å. In the tenth 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 Si(1)Mg10Bi2 cuboctahedra; corners with four equivalent Bi(1)Mg10Si2 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; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; and faces with two equivalent Mg(4)Mg12 cuboctahedra. There is one shorter (3.27 Å) and one longer (3.30 Å) Mg(4)-Mg(4) bond length. Both Mg(4)-Mg(5) bond lengths are 3.16 Å. Both Mg(4)-Mg(6) bond lengths are 3.22 Å. Both Mg(4)-Mg(7) bond lengths are 3.13 Å. In the eleventh 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 Si(1)Mg10Bi2 cuboctahedra; corners with four equivalent Bi(1)Mg10Si2 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; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; and faces with two equivalent Mg(4)Mg12 cuboctahedra. Both Mg(4)-Mg(5) bond lengths are 3.16 Å. Si(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 SiMg10Bi2 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra; corners with six equivalent Si(1)Mg10Bi2 cuboctahedra; corners with eight Mg(4,4,4)Mg12 cuboctahedra; edges with two equivalent Bi(1)Mg10Si2 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; and faces with two equivalent Bi(1)Mg10Si2 cuboctahedra. Both Si(1)-Bi(1) bond lengths are 3.28 Å. Bi(1) is bonded to two equivalent Mg(7); four equivalent Mg(3); four Mg(5,5); and two equivalent Si(1) atoms to form distorted BiMg10Si2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with six equivalent Bi(1)Mg10Si2 cuboctahedra; corners with eight Mg(4,4,4)Mg12 cuboctahedra; edges with two equivalent Si(1)Mg10Bi2 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; and faces with two equivalent Si(1)Mg10Bi2 cuboctahedra.