DOE OSTI2019
RbSn3As3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Rb1+ is bonded in a 6-coordinate geometry to six As3- atoms. There are a spread of Rb–As bond distances ranging from 3.55–3.81 Å. There are three inequivalent Sn+2.67+ sites. In the first Sn+2.67+ site, Sn+2.67+ is bonded to four As3- atoms to form corner-sharing SnAs4 tetrahedra. There are a spread of Sn–As bond distances ranging from 2.64–2.70 Å. In the second Sn+2.67+ site, Sn+2.67+ is bonded in a distorted trigonal non-coplanar geometry to three As3- atoms. There are one shorter (2.71 Å) and two longer (2.73 Å) Sn–As bond lengths. In the third Sn+2.67+ site, Sn+2.67+ is bonded in a water-like geometry to two equivalent As3- atoms. Both Sn–As bond lengths are 2.77 Å. There are three inequivalent As3- sites. In the first As3- site, As3- is bonded to three equivalent Rb1+ and three Sn+2.67+ atoms to form AsRb3Sn3 octahedra that share corners with two equivalent AsRb2Sn3 square pyramids, edges with four equivalent AsRb3Sn3 octahedra, and edges with three equivalent AsRb2Sn3 square pyramids. In the second As3- site, As3- is bonded to two equivalent Rb1+ and three Sn+2.67+ atoms to form AsRb2Sn3 square pyramids that share corners with two equivalent AsRb3Sn3 octahedra, edges with three equivalent AsRb3Sn3 octahedra, and edges with two equivalent AsRb2Sn3 square pyramids. The corner-sharing octahedral tilt angles are 15°. In the third As3- site, As3- is bonded in a rectangular see-saw-like geometry to one Rb1+ and three Sn+2.67+ atoms.