KFe2F6 crystallizes in the tetragonal P4/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to two equivalent F(1), two equivalent F(2), and two equivalent F(3) atoms. In the second K site, K(2) is bonded to four equivalent F(4) and eight equivalent F(6) atoms to form KF12 cuboctahedra that share faces with two equivalent K(2)F12 cuboctahedra and faces with eight equivalent Fe(2)F6 octahedra. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent F(1), two equivalent F(2), and two equivalent F(8) atoms to form corner-sharing FeF6 octahedra. The corner-sharing octahedral tilt angles range from 0-38°. In the second Fe site, Fe(2) is bonded to one F(1), one F(3), two equivalent F(4), and two equivalent F(6) atoms to form FeF6 octahedra that share  a cornercorner with one Fe(1)F6 octahedra,  a cornercorner with one Fe(3)F6 octahedra, corners with four equivalent Fe(2)F6 octahedra, and faces with two equivalent K(2)F12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-39°. In the third Fe site, Fe(3) is bonded to one F(2), one F(3), two equivalent F(5), and two equivalent F(7) atoms to form corner-sharing FeF6 octahedra. The corner-sharing octahedral tilt angles range from 4-39°. There are eight inequivalent F sites. In the first F site, F(6) is bonded in a distorted linear geometry to two equivalent K(2) and two equivalent Fe(2) atoms. In the second F site, F(7) is bonded in a linear geometry to two equivalent Fe(3) atoms. In the third F site, F(8) is bonded in a linear geometry to two equivalent Fe(1) atoms. In the fourth F site, F(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Fe(1), and one Fe(2) atom. In the fifth F site, F(2) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Fe(1), and one Fe(3) atom. In the sixth F site, F(3) is bonded in a 4-coordinate geometry to two equivalent K(1), one Fe(2), and one Fe(3) atom. In the seventh F site, F(4) is bonded in a distorted linear geometry to one K(2) and two equivalent Fe(2) atoms. In the eighth F site, F(5) is bonded in a linear geometry to two equivalent Fe(3) atoms.
KFe2F6 crystallizes in the tetragonal P4/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to two equivalent F(1), two equivalent F(2), and two equivalent F(3) atoms. Both K(1)-F(1) bond lengths are 2.89 Å. Both K(1)-F(2) bond lengths are 2.95 Å. Both K(1)-F(3) bond lengths are 2.81 Å. In the second K site, K(2) is bonded to four equivalent F(4) and eight equivalent F(6) atoms to form KF12 cuboctahedra that share faces with two equivalent K(2)F12 cuboctahedra and faces with eight equivalent Fe(2)F6 octahedra. All K(2)-F(4) bond lengths are 2.86 Å. All K(2)-F(6) bond lengths are 2.86 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent F(1), two equivalent F(2), and two equivalent F(8) atoms to form corner-sharing FeF6 octahedra. The corner-sharing octahedral tilt angles range from 0-38°. Both Fe(1)-F(1) bond lengths are 2.00 Å. Both Fe(1)-F(2) bond lengths are 2.02 Å. Both Fe(1)-F(8) bond lengths are 2.01 Å. In the second Fe site, Fe(2) is bonded to one F(1), one F(3), two equivalent F(4), and two equivalent F(6) atoms to form FeF6 octahedra that share  a cornercorner with one Fe(1)F6 octahedra,  a cornercorner with one Fe(3)F6 octahedra, corners with four equivalent Fe(2)F6 octahedra, and faces with two equivalent K(2)F12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-39°. The Fe(2)-F(1) bond length is 2.00 Å. The Fe(2)-F(3) bond length is 2.12 Å. Both Fe(2)-F(4) bond lengths are 2.01 Å. There is one shorter (2.01 Å) and one longer (2.10 Å) Fe(2)-F(6) bond length. In the third Fe site, Fe(3) is bonded to one F(2), one F(3), two equivalent F(5), and two equivalent F(7) atoms to form corner-sharing FeF6 octahedra. The corner-sharing octahedral tilt angles range from 4-39°. The Fe(3)-F(2) bond length is 2.00 Å. The Fe(3)-F(3) bond length is 2.02 Å. Both Fe(3)-F(5) bond lengths are 2.01 Å. There is one shorter (1.98 Å) and one longer (1.99 Å) Fe(3)-F(7) bond length. There are eight inequivalent F sites. In the first F site, F(6) is bonded in a distorted linear geometry to two equivalent K(2) and two equivalent Fe(2) atoms. In the second F site, F(7) is bonded in a linear geometry to two equivalent Fe(3) atoms. In the third F site, F(8) is bonded in a linear geometry to two equivalent Fe(1) atoms. In the fourth F site, F(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Fe(1), and one Fe(2) atom. In the fifth F site, F(2) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Fe(1), and one Fe(3) atom. In the sixth F site, F(3) is bonded in a 4-coordinate geometry to two equivalent K(1), one Fe(2), and one Fe(3) atom. In the seventh F site, F(4) is bonded in a distorted linear geometry to one K(2) and two equivalent Fe(2) atoms. In the eighth F site, F(5) is bonded in a linear geometry to two equivalent Fe(3) atoms.