DOI: 10.17188/1283598
title: Materials Data on K3As7 by Materials Project

description: K3As7 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to seven As+0.43- atoms. There are a spread of K–As bond distances ranging from 3.41–3.89 Å. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to nine As+0.43- atoms. There are a spread of K–As bond distances ranging from 3.40–3.73 Å. In the third K1+ site, K1+ is bonded in a 6-coordinate geometry to nine As+0.43- atoms. There are a spread of K–As bond distances ranging from 3.49–3.83 Å. In the fourth K1+ site, K1+ is bonded in a 4-coordinate geometry to five As+0.43- atoms. There are a spread of K–As bond distances ranging from 3.40–3.96 Å. In the fifth K1+ site, K1+ is bonded in a 9-coordinate geometry to nine As+0.43- atoms. There are a spread of K–As bond distances ranging from 3.36–3.66 Å. In the sixth K1+ site, K1+ is bonded in a 6-coordinate geometry to nine As+0.43- atoms. There are a spread of K–As bond distances ranging from 3.40–3.86 Å. There are fourteen inequivalent As+0.43- sites. In the first As+0.43- site, As+0.43- is bonded in a 5-coordinate geometry to two equivalent K1+ and three As+0.43- atoms. There are a spread of As–As bond distances ranging from 2.38–2.58 Å. In the second As+0.43- site, As+0.43- is bonded in a 7-coordinate geometry to four K1+ and three As+0.43- atoms. There are one shorter (2.37 Å) and two longer (2.56 Å) As–As bond lengths. In the third As+0.43- site, As+0.43- is bonded to five K1+ and two As+0.43- atoms to form distorted AsK5As2 pentagonal bipyramids that share corners with four AsK4As2 octahedra, a cornercorner with one AsK4As2 pentagonal pyramid, corners with two equivalent AsKAs3 trigonal pyramids, an edgeedge with one AsK4As2 octahedra, an edgeedge with one AsK5As2 pentagonal bipyramid, and edges with four AsK4As2 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 17–73°. The As–As bond length is 2.48 Å. In the fourth As+0.43- site, As+0.43- is bonded in a 7-coordinate geometry to four K1+ and three As+0.43- atoms. There are one shorter (2.38 Å) and one longer (2.59 Å) As–As bond lengths. In the fifth As+0.43- site, As+0.43- is bonded to four K1+ and two As+0.43- atoms to form distorted AsK4As2 pentagonal pyramids that share corners with three AsK4As2 octahedra, a cornercorner with one AsK5As2 pentagonal bipyramid, a cornercorner with one AsK4As2 pentagonal pyramid, a cornercorner with one AsKAs3 trigonal pyramid, an edgeedge with one AsK4As2 octahedra, and an edgeedge with one AsK5As2 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 62–68°. The As–As bond length is 2.45 Å. In the sixth As+0.43- site, As+0.43- is bonded in a distorted pentagonal planar geometry to two K1+ and three As+0.43- atoms. There are one shorter (2.44 Å) and one longer (2.46 Å) As–As bond lengths. In the seventh As+0.43- site, As+0.43- is bonded in a 7-coordinate geometry to four K1+ and three As+0.43- atoms. The As–As bond length is 2.38 Å. In the eighth As+0.43- site, As+0.43- is bonded to four K1+ and two As+0.43- atoms to form distorted AsK4As2 octahedra that share a cornercorner with one AsK4As2 octahedra, corners with two equivalent AsK5As2 pentagonal bipyramids, corners with two AsK4As2 pentagonal pyramids, edges with two AsK4As2 octahedra, an edgeedge with one AsK5As2 pentagonal bipyramid, and edges with two equivalent AsK4As2 pentagonal pyramids. The corner-sharing octahedral tilt angles are 62°. The As–As bond length is 2.44 Å. In the ninth As+0.43- site, As+0.43- is bonded in a 5-coordinate geometry to two K1+ and three As+0.43- atoms. There are one shorter (2.37 Å) and one longer (2.57 Å) As–As bond lengths. In the tenth As+0.43- site, As+0.43- is bonded to one K1+ and three As+0.43- atoms to form distorted AsKAs3 trigonal pyramids that share corners with two equivalent AsK5As2 pentagonal bipyramids and corners with two AsK4As2 pentagonal pyramids. The As–As bond length is 2.45 Å. In the eleventh As+0.43- site, As+0.43- is bonded in a 7-coordinate geometry to four K1+ and three As+0.43- atoms. The As–As bond length is 2.37 Å. In the twelfth As+0.43- site, As+0.43- is bonded to four K1+ and two As+0.43- atoms to form distorted AsK4As2 pentagonal pyramids that share corners with two AsK4As2 octahedra, corners with three AsK4As2 pentagonal pyramids, a cornercorner with one AsKAs3 trigonal pyramid, edges with two equivalent AsK4As2 octahedra, and edges with three equivalent AsK5As2 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 49–69°. In the thirteenth As+0.43- site, As+0.43- is bonded in a 6-coordinate geometry to four K1+ and two As+0.43- atoms. In the fourteenth As+0.43- site, As+0.43- is bonded to four K1+ and two As+0.43- atoms to form AsK4As2 octahedra that share a cornercorner with one AsK4As2 octahedra, corners with two equivalent AsK5As2 pentagonal bipyramids, corners with three AsK4As2 pentagonal pyramids, an edgeedge with one AsK4As2 octahedra, and an edgeedge with one AsK4As2 pentagonal pyramid. The corner-sharing octahedral tilt angles are 62°.