Materials Data on SnHg7(As2I3)2 by Materials Project
Hg7Sn(As2I3)2 crystallizes in the cubic P2_13 space group. The structure is three-dimensional. there are three inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded to two As3- and three I1- atoms to form distorted HgAs2I3 square pyramids that share corners with three equivalent HgAs2I4 octahedra, corners with two equivalent HgAs2I3 square pyramids, a cornercorner with one AsHg3As tetrahedra, an edgeedge with one HgAs2I4 octahedra, and edges with two equivalent HgAs2I3 square pyramids. The corner-sharing octahedra tilt angles range from 43–55°. There are one shorter (2.60 Å) and one longer (2.62 Å) Hg–As bond lengths. There are a spread of Hg–I bond distances ranging from 3.17–3.52 Å. In the second Hg2+ site, Hg2+ is bonded to two As3- and four I1- atoms to form distorted HgAs2I4 octahedra that share corners with two equivalent HgAs2I4 octahedra, corners with three equivalent HgAs2I3 square pyramids, a cornercorner with one AsHg3As tetrahedra, edges with four equivalent HgAs2I4 octahedra, and an edgeedge with one HgAs2I3 square pyramid. The corner-sharing octahedral tilt angles are 30°. There are one shorter (2.59 Å) and one longer (2.60 Å) Hg–As bond lengths. There are a spread of Hg–I bond distances ranging from 3.34–3.72 Å. In the third Hg2+ site, Hg2+ is bonded in a linear geometry to two As3- atoms. There are one shorter (2.54 Å) and one longer (2.55 Å) Hg–As bond lengths. Sn4+ is bonded in a 3-coordinate geometry to three equivalent I1- atoms. All Sn–I bond lengths are 2.98 Å. There are four inequivalent As3- sites. In the first As3- site, As3- is bonded to three equivalent Hg2+ and one As3- atom to form AsHg3As tetrahedra that share corners with three equivalent HgAs2I4 octahedra and corners with three equivalent AsHg4 tetrahedra. The corner-sharing octahedral tilt angles are 71°. The As–As bond length is 2.46 Å. In the second As3- site, As3- is bonded to four Hg2+ atoms to form corner-sharing AsHg4 tetrahedra. In the third As3- site, As3- is bonded to three equivalent Hg2+ and one As3- atom to form AsHg3As tetrahedra that share corners with three equivalent HgAs2I3 square pyramids and corners with three equivalent AsHg4 tetrahedra. In the fourth As3- site, As3- is bonded to four Hg2+ atoms to form corner-sharing AsHg4 tetrahedra. There are two inequivalent I1- sites. In the first I1- site, I1- is bonded in a 4-coordinate geometry to four Hg2+ atoms. In the second I1- site, I1- is bonded in a 1-coordinate geometry to three Hg2+ and one Sn4+ atom.