Materials Data on YbHg6As4Br7 by Materials Project
YbHg6As4Br7 crystallizes in the cubic Pa-3 space group. The structure is three-dimensional. Yb2+ is bonded to six equivalent Br1- atoms to form YbBr6 octahedra that share corners with six equivalent BrHg6Br6 cuboctahedra. All Yb–Br bond lengths are 2.87 Å. Hg2+ is bonded in a 7-coordinate geometry to two As+1.75- and five Br1- atoms. Both Hg–As bond lengths are 2.62 Å. There are a spread of Hg–Br bond distances ranging from 3.18–3.60 Å. There are two inequivalent As+1.75- sites. In the first As+1.75- site, As+1.75- is bonded to three equivalent Hg2+ and one As+1.75- atom to form AsHg3As tetrahedra that share corners with three equivalent AsHg3As tetrahedra and a faceface with one BrHg6Br6 cuboctahedra. The As–As bond length is 2.48 Å. In the second As+1.75- site, As+1.75- is bonded to three equivalent Hg2+ and one As+1.75- atom to form AsHg3As tetrahedra that share corners with three equivalent BrHg6Br6 cuboctahedra and corners with three equivalent AsHg3As tetrahedra. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 5-coordinate geometry to one Yb2+, four equivalent Hg2+, and one Br1- atom. The Br–Br bond length is 3.69 Å. In the second Br1- site, Br1- is bonded to six equivalent Hg2+ and six equivalent Br1- atoms to form distorted BrHg6Br6 cuboctahedra that share corners with six equivalent YbBr6 octahedra, corners with six equivalent AsHg3As tetrahedra, and faces with two equivalent AsHg3As tetrahedra. The corner-sharing octahedral tilt angles are 30°.