Materials Data on K3AlAs2 by Materials Project
K3AlAs2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are twelve inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 1-coordinate geometry to two K1+ and six As3- atoms. There are one shorter (3.24 Å) and one longer (3.46 Å) K–K bond lengths. There are a spread of K–As bond distances ranging from 3.29–3.63 Å. In the second K1+ site, K1+ is bonded in a 5-coordinate geometry to six As3- atoms. There are a spread of K–As bond distances ranging from 3.40–3.76 Å. In the third 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 3.26–3.49 Å. In the fourth K1+ site, K1+ is bonded in a 4-coordinate geometry to one K1+ and four As3- atoms. There are a spread of K–As bond distances ranging from 3.19–3.45 Å. In the fifth K1+ site, K1+ is bonded in a 4-coordinate geometry to one K1+ and four As3- atoms. The K–K bond length is 3.56 Å. There are a spread of K–As bond distances ranging from 3.33–3.52 Å. In the sixth 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 3.33–3.72 Å. In the seventh K1+ site, K1+ is bonded to one K1+ and four As3- atoms to form distorted KKAs4 trigonal pyramids that share corners with two AlAs4 tetrahedra and an edgeedge with one AlAs4 tetrahedra. There are a spread of K–As bond distances ranging from 3.26–3.47 Å. In the eighth K1+ site, K1+ is bonded in a 2-coordinate geometry to three As3- atoms. There are a spread of K–As bond distances ranging from 3.43–3.82 Å. In the ninth K1+ site, K1+ is bonded in a 4-coordinate geometry to four As3- atoms. There are a spread of K–As bond distances ranging from 3.33–3.66 Å. In the tenth K1+ site, K1+ is bonded in a 8-coordinate geometry to two K1+ and five As3- atoms. The K–K bond length is 3.38 Å. There are a spread of K–As bond distances ranging from 3.54–3.88 Å. In the eleventh K1+ site, K1+ is bonded in a 6-coordinate geometry to two K1+ and four As3- atoms. There are one shorter (3.33 Å) and one longer (3.42 Å) K–K bond lengths. There are a spread of K–As bond distances ranging from 3.34–3.66 Å. In the twelfth K1+ site, K1+ is bonded in a 3-coordinate geometry to one K1+ and four As3- atoms. There are a spread of K–As bond distances ranging from 3.35–3.78 Å. There are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four As3- atoms to form AlAs4 tetrahedra that share a cornercorner with one KKAs4 trigonal pyramid and edges with two AlAs4 tetrahedra. There are three shorter (2.54 Å) and one longer (2.56 Å) Al–As bond lengths. In the second Al3+ site, Al3+ is bonded to four As3- atoms to form AlAs4 tetrahedra that share a cornercorner with one KKAs4 trigonal pyramid, edges with two AlAs4 tetrahedra, and an edgeedge with one KKAs4 trigonal pyramid. There are a spread of Al–As bond distances ranging from 2.55–2.61 Å. In the third Al3+ site, Al3+ is bonded in a trigonal planar geometry to three As3- atoms. There are a spread of Al–As bond distances ranging from 2.37–2.49 Å. In the fourth Al3+ site, Al3+ is bonded in a trigonal planar geometry to three As3- atoms. There are a spread of Al–As bond distances ranging from 2.36–2.48 Å. There are eight inequivalent As3- sites. In the first As3- site, As3- is bonded in a 9-coordinate geometry to seven K1+ and two Al3+ atoms. In the second As3- site, As3- is bonded in a 2-coordinate geometry to seven K1+ and two equivalent Al3+ atoms. In the third As3- site, As3- is bonded in a 9-coordinate geometry to seven K1+ and two Al3+ atoms. In the fourth As3- site, As3- is bonded in a 2-coordinate geometry to seven K1+ and two equivalent Al3+ atoms. In the fifth As3- site, As3- is bonded in a 1-coordinate geometry to six K1+ and one Al3+ atom. In the sixth As3- site, As3- is bonded in a 1-coordinate geometry to seven K1+ and one Al3+ atom. In the seventh As3- site, As3- is bonded in a 4-coordinate geometry to five K1+ and two Al3+ atoms. In the eighth As3- site, As3- is bonded in a 8-coordinate geometry to six K1+ and two Al3+ atoms.