K2(FeSe)5 crystallizes in the tetragonal I4/m space group. K(1) is bonded in a distorted body-centered cubic geometry to two equivalent Se(2) and six equivalent Se(1) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one Se(2) and three equivalent Se(1) atoms to form a mixture of distorted edge and corner-sharing FeSe4 tetrahedra. In the second Fe site, Fe(2) is bonded to four equivalent Se(1) atoms to form a mixture of distorted edge and corner-sharing FeSe4 tetrahedra. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 7-coordinate geometry to three equivalent K(1), one Fe(2), and three equivalent Fe(1) atoms. In the second Se site, Se(2) is bonded in a 8-coordinate geometry to four equivalent K(1) and four equivalent Fe(1) atoms.
K2(FeSe)5 crystallizes in the tetragonal I4/m space group. K(1) is bonded in a distorted body-centered cubic geometry to two equivalent Se(2) and six equivalent Se(1) atoms. Both K(1)-Se(2) bond lengths are 3.47 Å. There are a spread of K(1)-Se(1) bond distances ranging from 3.32-3.53 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one Se(2) and three equivalent Se(1) atoms to form a mixture of distorted edge and corner-sharing FeSe4 tetrahedra. The Fe(1)-Se(2) bond length is 2.49 Å. There are two shorter (2.47 Å) and one longer (2.48 Å) Fe(1)-Se(1) bond length. In the second Fe site, Fe(2) is bonded to four equivalent Se(1) atoms to form a mixture of distorted edge and corner-sharing FeSe4 tetrahedra. All Fe(2)-Se(1) bond lengths are 2.46 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 7-coordinate geometry to three equivalent K(1), one Fe(2), and three equivalent Fe(1) atoms. In the second Se site, Se(2) is bonded in a 8-coordinate geometry to four equivalent K(1) and four equivalent Fe(1) atoms.