Materials Data on TiHg6As4Br7 by Materials Project
TiHg6As4Br7 crystallizes in the cubic Pa-3 space group. The structure is three-dimensional. Ti4+ is bonded to six equivalent Br1- atoms to form TiBr6 octahedra that share edges with twelve equivalent HgAs2Br5 pentagonal bipyramids. All Ti–Br bond lengths are 2.56 Å. Hg2+ is bonded to two As+2.25- and five Br1- atoms to form distorted HgAs2Br5 pentagonal bipyramids that share corners with eleven equivalent HgAs2Br5 pentagonal bipyramids, corners with two AsHg3As tetrahedra, edges with two equivalent TiBr6 octahedra, edges with two equivalent HgAs2Br5 pentagonal bipyramids, and faces with two equivalent HgAs2Br5 pentagonal bipyramids. There are one shorter (2.61 Å) and one longer (2.62 Å) Hg–As bond lengths. There are a spread of Hg–Br bond distances ranging from 3.33–3.55 Å. There are two inequivalent As+2.25- sites. In the first As+2.25- site, As+2.25- is bonded to three equivalent Hg2+ and one As+2.25- atom to form AsHg3As tetrahedra that share corners with three equivalent HgAs2Br5 pentagonal bipyramids and corners with three equivalent AsHg3As tetrahedra. The As–As bond length is 2.53 Å. In the second As+2.25- site, As+2.25- is bonded to three equivalent Hg2+ and one As+2.25- atom to form AsHg3As tetrahedra that share corners with three equivalent HgAs2Br5 pentagonal bipyramids and corners with three equivalent AsHg3As tetrahedra. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a distorted single-bond geometry to one Ti4+ and four equivalent Hg2+ atoms. In the second Br1- site, Br1- is bonded in a 12-coordinate geometry to six equivalent Hg2+ atoms.