Materials Data on K5SnAs3 by Materials Project
K5SnAs3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are five inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to four As3- atoms to form distorted KAs4 tetrahedra that share corners with three equivalent SnAs4 tetrahedra, corners with five KAs4 tetrahedra, an edgeedge with one KAs4 tetrahedra, and an edgeedge with one SnAs4 tetrahedra. There are a spread of K–As bond distances ranging from 3.33–3.40 Å. In the second K1+ site, K1+ is bonded to four As3- atoms to form distorted KAs4 tetrahedra that share corners with three equivalent KAs4 tetrahedra, corners with five equivalent SnAs4 tetrahedra, and edges with two KAs4 tetrahedra. There are a spread of K–As bond distances ranging from 3.38–3.56 Å. In the third K1+ site, K1+ is bonded in a 3-coordinate geometry to four As3- atoms. There are a spread of K–As bond distances ranging from 3.43–3.92 Å. In the fourth K1+ site, K1+ is bonded in a distorted see-saw-like geometry to four As3- atoms. There are a spread of K–As bond distances ranging from 3.36–3.65 Å. In the fifth K1+ site, K1+ is bonded in a 3-coordinate geometry to three As3- atoms. There are a spread of K–As bond distances ranging from 3.34–3.58 Å. Sn4+ is bonded to four As3- atoms to form SnAs4 tetrahedra that share corners with eight KAs4 tetrahedra, an edgeedge with one KAs4 tetrahedra, and an edgeedge with one SnAs4 tetrahedra. There are a spread of Sn–As bond distances ranging from 2.67–2.77 Å. There are three inequivalent As3- sites. In the first As3- site, As3- is bonded in a 9-coordinate geometry to seven K1+ and one Sn4+ atom. In the second As3- site, As3- is bonded in a 7-coordinate geometry to five K1+ and two equivalent Sn4+ atoms. In the third As3- site, As3- is bonded in a 7-coordinate geometry to seven K1+ and one Sn4+ atom.