Materials Data on K9FeS7 by Materials Project
K9FeS7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are nine inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 6-coordinate geometry to six S+1.71- atoms. There are a spread of K–S bond distances ranging from 3.17–3.60 Å. In the second K1+ site, K1+ is bonded in a 4-coordinate geometry to five S+1.71- atoms. There are a spread of K–S bond distances ranging from 3.24–3.86 Å. In the third K1+ site, K1+ is bonded in a 6-coordinate geometry to six S+1.71- atoms. There are a spread of K–S bond distances ranging from 3.17–3.49 Å. In the fourth K1+ site, K1+ is bonded to six S+1.71- atoms to form distorted KS6 octahedra that share corners with two equivalent KS6 octahedra, corners with two equivalent FeS4 tetrahedra, and a cornercorner with one KS4 trigonal pyramid. The corner-sharing octahedral tilt angles are 63°. There are a spread of K–S bond distances ranging from 3.15–3.56 Å. In the fifth K1+ site, K1+ is bonded in a 5-coordinate geometry to five S+1.71- atoms. There are a spread of K–S bond distances ranging from 3.18–3.40 Å. In the sixth K1+ site, K1+ is bonded in a 5-coordinate geometry to five S+1.71- atoms. There are a spread of K–S bond distances ranging from 3.12–3.39 Å. In the seventh K1+ site, K1+ is bonded to four S+1.71- atoms to form distorted KS4 trigonal pyramids that share a cornercorner with one KS6 octahedra, corners with three equivalent FeS4 tetrahedra, and an edgeedge with one KS4 trigonal pyramid. The corner-sharing octahedral tilt angles are 49°. There are a spread of K–S bond distances ranging from 3.09–3.36 Å. In the eighth K1+ site, K1+ is bonded in a 6-coordinate geometry to six S+1.71- atoms. There are a spread of K–S bond distances ranging from 3.12–3.60 Å. In the ninth K1+ site, K1+ is bonded in a 6-coordinate geometry to six S+1.71- atoms. There are a spread of K–S bond distances ranging from 3.12–3.77 Å. Fe3+ is bonded to four S+1.71- atoms to form FeS4 tetrahedra that share corners with two equivalent KS6 octahedra and corners with three equivalent KS4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 36–44°. There are three shorter (2.31 Å) and one longer (2.32 Å) Fe–S bond lengths. There are seven inequivalent S+1.71- sites. In the first S+1.71- site, S+1.71- is bonded in a 8-coordinate geometry to eight K1+ atoms. In the second S+1.71- site, S+1.71- is bonded in a 1-coordinate geometry to seven K1+ and one Fe3+ atom. In the third S+1.71- site, S+1.71- is bonded in a 1-coordinate geometry to seven K1+ and one Fe3+ atom. In the fourth S+1.71- site, S+1.71- is bonded in a 7-coordinate geometry to seven K1+ and one S+1.71- atom. The S–S bond length is 2.15 Å. In the fifth S+1.71- site, S+1.71- is bonded in a 1-coordinate geometry to six K1+ and one Fe3+ atom. In the sixth S+1.71- site, S+1.71- is bonded in a 7-coordinate geometry to six K1+ and one Fe3+ atom. In the seventh S+1.71- site, S+1.71- is bonded in a 9-coordinate geometry to eight K1+ and one S+1.71- atom.