Materials Data on K(SnSe2)2 by Materials Project
K(SnSe2)2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of K–Se bond distances ranging from 3.36–3.97 Å. There are three inequivalent Sn+3.50+ sites. In the first Sn+3.50+ site, Sn+3.50+ is bonded to four Se2- atoms to form corner-sharing SnSe4 tetrahedra. There are a spread of Sn–Se bond distances ranging from 2.53–2.60 Å. In the second Sn+3.50+ site, Sn+3.50+ is bonded to four Se2- atoms to form corner-sharing SnSe4 tetrahedra. There are a spread of Sn–Se bond distances ranging from 2.51–2.61 Å. In the third Sn+3.50+ site, Sn+3.50+ is bonded in a rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Sn–Se bond distances ranging from 2.70–3.17 Å. There are five inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted water-like geometry to two equivalent K1+ and two equivalent Sn+3.50+ atoms. In the second Se2- site, Se2- is bonded to two equivalent K1+ and two Sn+3.50+ atoms to form a mixture of distorted edge and corner-sharing SeK2Sn2 trigonal pyramids. In the third Se2- site, Se2- is bonded in a 2-coordinate geometry to one K1+ and two Sn+3.50+ atoms. In the fourth Se2- site, Se2- is bonded in a distorted L-shaped geometry to two equivalent K1+ and two Sn+3.50+ atoms. In the fifth Se2- site, Se2- is bonded to three equivalent K1+ and two Sn+3.50+ atoms to form distorted SeK3Sn2 trigonal bipyramids that share corners with three equivalent SeK3Sn2 trigonal bipyramids, corners with two equivalent SeK2Sn2 trigonal pyramids, edges with two equivalent SeK3Sn2 trigonal bipyramids, and an edgeedge with one SeK2Sn2 trigonal pyramid.