DOE OSTI2019
Mg149Os is alpha Samarium-derived structured and crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. there are twenty-seven inequivalent Mg sites. In the first Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share a cornercorner with one OsMg12 cuboctahedra, corners with sixteen MgMg12 cuboctahedra, edges with fourteen MgMg12 cuboctahedra, and faces with nineteen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.15–3.33 Å. In the second Mg site, Mg is bonded in a distorted single-bond geometry to seven Mg and one Os atom. There are a spread of Mg–Mg bond distances ranging from 3.20–3.26 Å. The Mg–Os bond length is 2.98 Å. In the third Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with sixteen MgMg12 cuboctahedra, an edgeedge with one OsMg12 cuboctahedra, edges with thirteen MgMg12 cuboctahedra, and faces with eighteen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.15–3.21 Å. In the fourth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.18–3.20 Å. In the fifth Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with sixteen MgMg12 cuboctahedra, an edgeedge with one OsMg12 cuboctahedra, edges with seventeen MgMg12 cuboctahedra, and faces with sixteen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.16–3.23 Å. In the sixth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are six shorter (3.18 Å) and two longer (3.19 Å) Mg–Mg bond lengths. In the seventh Mg site, Mg is bonded in a distorted single-bond geometry to seven Mg and one Os atom. There are a spread of Mg–Mg bond distances ranging from 3.22–3.32 Å. The Mg–Os bond length is 2.98 Å. In the eighth Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with sixteen MgMg12 cuboctahedra, an edgeedge with one OsMg12 cuboctahedra, edges with fifteen MgMg12 cuboctahedra, and faces with seventeen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.15–3.22 Å. In the ninth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.18–3.20 Å. In the tenth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are one shorter (3.19 Å) and four longer (3.20 Å) Mg–Mg bond lengths. In the eleventh Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.16–3.20 Å. In the twelfth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. All Mg–Mg bond lengths are 3.20 Å. In the thirteenth Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with sixteen MgMg12 cuboctahedra, edges with fifteen MgMg12 cuboctahedra, a faceface with one OsMg12 cuboctahedra, and faces with fifteen MgMg12 cuboctahedra. All Mg–Mg bond lengths are 3.16 Å. In the fourteenth Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share a cornercorner with one OsMg12 cuboctahedra, corners with fifteen MgMg12 cuboctahedra, edges with seventeen MgMg12 cuboctahedra, and faces with seventeen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.15–3.22 Å. In the fifteenth Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with twelve MgMg12 cuboctahedra, edges with eighteen MgMg12 cuboctahedra, a faceface with one OsMg12 cuboctahedra, and faces with sixteen MgMg12 cuboctahedra. All Mg–Mg bond lengths are 3.21 Å. In the sixteenth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.17–3.21 Å. In the seventeenth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.18–3.20 Å. In the eighteenth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.18–3.20 Å. In the nineteenth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.18–3.20 Å. In the twentieth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are two shorter (3.18 Å) and one longer (3.19 Å) Mg–Mg bond lengths. In the twenty-first Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are four shorter (3.17 Å) and two longer (3.18 Å) Mg–Mg bond lengths. In the twenty-second Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are two shorter (3.17 Å) and two longer (3.19 Å) Mg–Mg bond lengths. In the twenty-third Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are two shorter (3.17 Å) and three longer (3.18 Å) Mg–Mg bond lengths. In the twenty-fourth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are two shorter (3.18 Å) and one longer (3.19 Å) Mg–Mg bond lengths. In the twenty-fifth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. In the twenty-sixth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. There are two shorter (3.19 Å) and two longer (3.20 Å) Mg–Mg bond lengths. In the twenty-seventh Mg site, Mg is bonded to twelve Mg atoms to form a mixture of corner, edge, and face-sharing MgMg12 cuboctahedra. Os is bonded to twelve Mg atoms to form OsMg12 cuboctahedra that share corners with eighteen MgMg12 cuboctahedra, edges with eighteen MgMg12 cuboctahedra, and faces with eight MgMg12 cuboctahedra.