Materials Data on K5CuAs2 by Materials Project
KK4CuAs2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional and consists of two potassium molecules and one K4CuAs2 framework. In the K4CuAs2 framework, there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to four equivalent As3- atoms to form a mixture of distorted edge and corner-sharing KAs4 tetrahedra. There are one shorter (3.33 Å) and three longer (3.65 Å) K–As bond lengths. In the second K1+ site, K1+ is bonded in a trigonal planar geometry to three equivalent As3- atoms. All K–As bond lengths are 3.36 Å. Cu1+ is bonded in a linear geometry to two equivalent As3- atoms. Both Cu–As bond lengths are 2.34 Å. As3- is bonded in a 8-coordinate geometry to seven K1+ and one Cu1+ atom.