KAgSnSe3 crystallizes in the tetragonal P4cc space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. In the second K site, K(2) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(3) atoms. In the third K site, K(3) is bonded in a 8-coordinate geometry to four equivalent Se(2) and four equivalent Se(3) atoms. In the fourth K site, K(4) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. Ag(1) is bonded in a linear geometry to one Se(2) and one Se(3) atom. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form edge-sharing SnSe4 tetrahedra. In the second Sn site, Sn(2) is bonded to two equivalent Se(1) and two equivalent Se(3) atoms to form edge-sharing SnSe4 tetrahedra. There are three inequivalent Se sites. In the first Se site, Se(2) is bonded in a 5-coordinate geometry to one K(1), one K(3), one K(4), one Ag(1), and one Sn(1) atom. In the second Se site, Se(3) is bonded in a distorted rectangular see-saw-like geometry to one K(2), one K(3), one Ag(1), and one Sn(2) atom. In the third Se site, Se(1) is bonded to one K(1), one K(2), one K(4), one Sn(1), and one Sn(2) atom to form a mixture of distorted edge and corner-sharing SeK3Sn2 trigonal bipyramids.
KAgSnSe3 crystallizes in the tetragonal P4cc space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. All K(1)-Se(1) bond lengths are 3.61 Å. All K(1)-Se(2) bond lengths are 3.37 Å. In the second K site, K(2) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(3) atoms. All K(2)-Se(1) bond lengths are 3.59 Å. All K(2)-Se(3) bond lengths are 3.32 Å. In the third K site, K(3) is bonded in a 8-coordinate geometry to four equivalent Se(2) and four equivalent Se(3) atoms. All K(3)-Se(2) bond lengths are 3.66 Å. All K(3)-Se(3) bond lengths are 3.45 Å. In the fourth K site, K(4) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. All K(4)-Se(1) bond lengths are 3.38 Å. All K(4)-Se(2) bond lengths are 3.56 Å. Ag(1) is bonded in a linear geometry to one Se(2) and one Se(3) atom. The Ag(1)-Se(2) bond length is 2.51 Å. The Ag(1)-Se(3) bond length is 2.50 Å. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form edge-sharing SnSe4 tetrahedra. Both Sn(1)-Se(1) bond lengths are 2.60 Å. Both Sn(1)-Se(2) bond lengths are 2.54 Å. In the second Sn site, Sn(2) is bonded to two equivalent Se(1) and two equivalent Se(3) atoms to form edge-sharing SnSe4 tetrahedra. Both Sn(2)-Se(1) bond lengths are 2.61 Å. Both Sn(2)-Se(3) bond lengths are 2.53 Å. There are three inequivalent Se sites. In the first Se site, Se(2) is bonded in a 5-coordinate geometry to one K(1), one K(3), one K(4), one Ag(1), and one Sn(1) atom. In the second Se site, Se(3) is bonded in a distorted rectangular see-saw-like geometry to one K(2), one K(3), one Ag(1), and one Sn(2) atom. In the third Se site, Se(1) is bonded to one K(1), one K(2), one K(4), one Sn(1), and one Sn(2) atom to form a mixture of distorted edge and corner-sharing SeK3Sn2 trigonal bipyramids.