K(SnSe2)2 crystallizes in the monoclinic Cm space group. K(1) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), one Se(4), two equivalent Se(1), and three equivalent Se(5) atoms. There are three inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one Se(2), one Se(4), and two equivalent Se(3) atoms to form corner-sharing SnSe4 tetrahedra. In the second Sn site, Sn(2) is bonded to one Se(3), one Se(5), and two equivalent Se(1) atoms to form corner-sharing SnSe4 tetrahedra. In the third Sn site, Sn(3) is bonded in a rectangular see-saw-like geometry to one Se(2), one Se(4), and two equivalent Se(5) atoms. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted water-like geometry to two equivalent K(1) and two equivalent Sn(2) atoms. In the second Se site, Se(2) is bonded to two equivalent K(1), one Sn(1), and one Sn(3) atom to form a mixture of corner and edge-sharing SeK2Sn2 trigonal pyramids. In the third Se site, Se(3) is bonded in a distorted trigonal planar geometry to one K(1), one Sn(1), and one Sn(2) atom. In the fourth Se site, Se(4) is bonded in a distorted L-shaped geometry to two equivalent K(1), one Sn(1), and one Sn(3) atom. In the fifth Se site, Se(5) is bonded to three equivalent K(1), one Sn(2), and one Sn(3) atom to form distorted SeK3Sn2 trigonal bipyramids that share corners with three equivalent Se(5)K3Sn2 trigonal bipyramids, corners with two equivalent Se(2)K2Sn2 trigonal pyramids, edges with two equivalent Se(5)K3Sn2 trigonal bipyramids, and  an edgeedge with one Se(2)K2Sn2 trigonal pyramid.
K(SnSe2)2 crystallizes in the monoclinic Cm space group. K(1) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), one Se(4), two equivalent Se(1), and three equivalent Se(5) atoms. The K(1)-Se(2) bond length is 3.47 Å. The K(1)-Se(3) bond length is 3.61 Å. The K(1)-Se(4) bond length is 3.85 Å. There is one shorter (3.83 Å) and one longer (3.95 Å) K(1)-Se(1) bond length. There are a spread of K(1)-Se(5) bond distances ranging from 3.32-3.50 Å. There are three inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one Se(2), one Se(4), and two equivalent Se(3) atoms to form corner-sharing SnSe4 tetrahedra. The Sn(1)-Se(2) bond length is 2.51 Å. The Sn(1)-Se(4) bond length is 2.50 Å. Both Sn(1)-Se(3) bond lengths are 2.57 Å. In the second Sn site, Sn(2) is bonded to one Se(3), one Se(5), and two equivalent Se(1) atoms to form corner-sharing SnSe4 tetrahedra. The Sn(2)-Se(3) bond length is 2.56 Å. The Sn(2)-Se(5) bond length is 2.48 Å. There is one shorter (2.56 Å) and one longer (2.58 Å) Sn(2)-Se(1) bond length. In the third Sn site, Sn(3) is bonded in a rectangular see-saw-like geometry to one Se(2), one Se(4), and two equivalent Se(5) atoms. The Sn(3)-Se(2) bond length is 2.70 Å. The Sn(3)-Se(4) bond length is 2.68 Å. Both Sn(3)-Se(5) bond lengths are 3.14 Å. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted water-like geometry to two equivalent K(1) and two equivalent Sn(2) atoms. In the second Se site, Se(2) is bonded to two equivalent K(1), one Sn(1), and one Sn(3) atom to form a mixture of corner and edge-sharing SeK2Sn2 trigonal pyramids. In the third Se site, Se(3) is bonded in a distorted trigonal planar geometry to one K(1), one Sn(1), and one Sn(2) atom. In the fourth Se site, Se(4) is bonded in a distorted L-shaped geometry to two equivalent K(1), one Sn(1), and one Sn(3) atom. In the fifth Se site, Se(5) is bonded to three equivalent K(1), one Sn(2), and one Sn(3) atom to form distorted SeK3Sn2 trigonal bipyramids that share corners with three equivalent Se(5)K3Sn2 trigonal bipyramids, corners with two equivalent Se(2)K2Sn2 trigonal pyramids, edges with two equivalent Se(5)K3Sn2 trigonal bipyramids, and  an edgeedge with one Se(2)K2Sn2 trigonal pyramid.