K4Sn(TeSe)2 crystallizes in the orthorhombic Pnma space group. There are three inequivalent K sites. In the first K site, K(1) is bonded to two equivalent Te(1), two equivalent Te(2), and two equivalent Se(1) atoms to form distorted edge-sharing KTe4Se2 octahedra. In the second K site, K(2) is bonded in a 7-coordinate geometry to one Sn(1), two equivalent Te(1), two equivalent Te(2), and two equivalent Se(1) atoms. In the third K site, K(3) is bonded in a 5-coordinate geometry to one Te(1), one Te(2), and four equivalent Se(1) atoms. Sn(1) is bonded in a 6-coordinate geometry to two equivalent K(2), one Te(1), one Te(2), and two equivalent Se(1) atoms. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded in a 8-coordinate geometry to one K(3), two equivalent K(1), four equivalent K(2), and one Sn(1) atom. In the second Te site, Te(2) is bonded in a 8-coordinate geometry to one K(3), two equivalent K(1), four equivalent K(2), and one Sn(1) atom. Se(1) is bonded to one K(1), two equivalent K(2), two equivalent K(3), and one Sn(1) atom to form a mixture of distorted corner and edge-sharing SeK5Sn octahedra. The corner-sharing octahedral tilt angles range from 0-40°.
K4Sn(TeSe)2 crystallizes in the orthorhombic Pnma space group. There are three inequivalent K sites. In the first K site, K(1) is bonded to two equivalent Te(1), two equivalent Te(2), and two equivalent Se(1) atoms to form distorted edge-sharing KTe4Se2 octahedra. Both K(1)-Te(1) bond lengths are 3.75 Å. Both K(1)-Te(2) bond lengths are 3.85 Å. Both K(1)-Se(1) bond lengths are 3.36 Å. In the second K site, K(2) is bonded in a 7-coordinate geometry to one Sn(1), two equivalent Te(1), two equivalent Te(2), and two equivalent Se(1) atoms. The K(2)-Sn(1) bond length is 3.67 Å. There is one shorter (3.53 Å) and one longer (3.93 Å) K(2)-Te(1) bond length. There is one shorter (3.66 Å) and one longer (3.80 Å) K(2)-Te(2) bond length. There is one shorter (3.32 Å) and one longer (3.52 Å) K(2)-Se(1) bond length. In the third K site, K(3) is bonded in a 5-coordinate geometry to one Te(1), one Te(2), and four equivalent Se(1) atoms. The K(3)-Te(1) bond length is 4.12 Å. The K(3)-Te(2) bond length is 3.68 Å. There are two shorter (3.40 Å) and two longer (3.49 Å) K(3)-Se(1) bond lengths. Sn(1) is bonded in a 6-coordinate geometry to two equivalent K(2), one Te(1), one Te(2), and two equivalent Se(1) atoms. The Sn(1)-Te(1) bond length is 2.80 Å. The Sn(1)-Te(2) bond length is 2.81 Å. Both Sn(1)-Se(1) bond lengths are 2.55 Å. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded in a 8-coordinate geometry to one K(3), two equivalent K(1), four equivalent K(2), and one Sn(1) atom. In the second Te site, Te(2) is bonded in a 8-coordinate geometry to one K(3), two equivalent K(1), four equivalent K(2), and one Sn(1) atom. Se(1) is bonded to one K(1), two equivalent K(2), two equivalent K(3), and one Sn(1) atom to form a mixture of distorted corner and edge-sharing SeK5Sn octahedra. The corner-sharing octahedral tilt angles range from 0-40°.