KFeF4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 9-coordinate geometry to one F(4), two equivalent F(1), two equivalent F(2), and four equivalent F(3) atoms. In the second K site, K(2) is bonded in a 7-coordinate geometry to one F(5), two equivalent F(3), and four equivalent F(2) atoms. Fe(1) is bonded to one F(2), one F(3), one F(4), one F(5), and two equivalent F(1) atoms to form corner-sharing FeF6 octahedra. The corner-sharing octahedral tilt angles range from 22-35°. There are five inequivalent F sites. In the first F site, F(1) is bonded in a distorted bent 150 degrees geometry to one K(1) and two equivalent Fe(1) atoms. In the second F site, F(2) is bonded to one K(1), two equivalent K(2), and one Fe(1) atom to form a mixture of distorted edge and corner-sharing FK3Fe tetrahedra. In the third F site, F(3) is bonded to one K(2), two equivalent K(1), and one Fe(1) atom to form a mixture of distorted edge and corner-sharing FK3Fe tetrahedra. In the fourth F site, F(4) is bonded in a distorted bent 150 degrees geometry to one K(1) and two equivalent Fe(1) atoms. In the fifth F site, F(5) is bonded in a distorted bent 150 degrees geometry to one K(2) and two equivalent Fe(1) atoms.
KFeF4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 9-coordinate geometry to one F(4), two equivalent F(1), two equivalent F(2), and four equivalent F(3) atoms. The K(1)-F(4) bond length is 2.88 Å. Both K(1)-F(1) bond lengths are 3.09 Å. Both K(1)-F(2) bond lengths are 2.67 Å. There are two shorter (2.67 Å) and two longer (2.71 Å) K(1)-F(3) bond lengths. In the second K site, K(2) is bonded in a 7-coordinate geometry to one F(5), two equivalent F(3), and four equivalent F(2) atoms. The K(2)-F(5) bond length is 2.79 Å. Both K(2)-F(3) bond lengths are 2.63 Å. There are two shorter (2.63 Å) and two longer (2.66 Å) K(2)-F(2) bond lengths. Fe(1) is bonded to one F(2), one F(3), one F(4), one F(5), and two equivalent F(1) atoms to form corner-sharing FeF6 octahedra. The corner-sharing octahedral tilt angles range from 22-35°. The Fe(1)-F(2) bond length is 1.88 Å. The Fe(1)-F(3) bond length is 1.88 Å. The Fe(1)-F(4) bond length is 1.98 Å. The Fe(1)-F(5) bond length is 1.98 Å. Both Fe(1)-F(1) bond lengths are 1.98 Å. There are five inequivalent F sites. In the first F site, F(1) is bonded in a distorted bent 150 degrees geometry to one K(1) and two equivalent Fe(1) atoms. In the second F site, F(2) is bonded to one K(1), two equivalent K(2), and one Fe(1) atom to form a mixture of distorted edge and corner-sharing FK3Fe tetrahedra. In the third F site, F(3) is bonded to one K(2), two equivalent K(1), and one Fe(1) atom to form a mixture of distorted edge and corner-sharing FK3Fe tetrahedra. In the fourth F site, F(4) is bonded in a distorted bent 150 degrees geometry to one K(1) and two equivalent Fe(1) atoms. In the fifth F site, F(5) is bonded in a distorted bent 150 degrees geometry to one K(2) and two equivalent Fe(1) atoms.