Materials Data on HfAu9 by Materials Project
HfAu9 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Hf4+ is bonded to twelve Au+0.44- atoms to form HfAu12 cuboctahedra that share corners with six equivalent AuAu12 cuboctahedra, edges with four equivalent HfAu12 cuboctahedra, edges with eight AuAu12 cuboctahedra, faces with two equivalent HfAu12 cuboctahedra, and faces with two equivalent AuAu12 cuboctahedra. There are a spread of Hf–Au bond distances ranging from 2.93–2.96 Å. There are five inequivalent Au+0.44- sites. In the first Au+0.44- site, Au+0.44- is bonded to twelve Au+0.44- atoms to form AuAu12 cuboctahedra that share corners with six equivalent AuHf3Au cuboctahedra, edges with four equivalent HfAu12 cuboctahedra, edges with eight AuAu12 cuboctahedra, and faces with eight AuAu12 cuboctahedra. There are eight shorter (2.96 Å) and four longer (2.97 Å) Au–Au bond lengths. In the second Au+0.44- site, Au+0.44- is bonded to twelve Au+0.44- atoms to form AuAu12 cuboctahedra that share corners with three equivalent HfAu12 cuboctahedra, corners with five AuAu12 cuboctahedra, edges with two equivalent HfAu12 cuboctahedra, edges with six AuAu12 cuboctahedra, a faceface with one HfAu12 cuboctahedra, and faces with eight AuAu12 cuboctahedra. There are a spread of Au–Au bond distances ranging from 2.94–3.00 Å. In the third Au+0.44- site, Au+0.44- is bonded to three equivalent Hf4+ and one Au+0.44- atom to form distorted AuHf3Au cuboctahedra that share corners with fourteen AuAu12 cuboctahedra and edges with three equivalent AuHf3Au cuboctahedra. In the fourth Au+0.44- site, Au+0.44- is bonded in a distorted single-bond geometry to one Hf4+ and six Au+0.44- atoms. In the fifth Au+0.44- site, Au+0.44- is bonded in a distorted L-shaped geometry to two equivalent Hf4+ and three Au+0.44- atoms.