K3NaFeCl6 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to two equivalent Cl(2) and four equivalent Cl(1) atoms to form distorted KCl6 octahedra that share faces with two equivalent Fe(1)Cl6 octahedra. In the second K site, K(2) is bonded in a linear geometry to two equivalent Cl(1) atoms. Na(1) is bonded in a linear geometry to two equivalent Cl(2) atoms. Fe(1) is bonded to two equivalent Cl(2) and four equivalent Cl(1) atoms to form distorted FeCl6 octahedra that share faces with two equivalent K(1)Cl6 octahedra. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a distorted T-shaped geometry to one K(1), one K(2), and one Fe(1) atom. In the second Cl site, Cl(2) is bonded in a 3-coordinate geometry to one K(1), one Na(1), and one Fe(1) atom.
K3NaFeCl6 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to two equivalent Cl(2) and four equivalent Cl(1) atoms to form distorted KCl6 octahedra that share faces with two equivalent Fe(1)Cl6 octahedra. Both K(1)-Cl(2) bond lengths are 2.98 Å. All K(1)-Cl(1) bond lengths are 2.84 Å. In the second K site, K(2) is bonded in a linear geometry to two equivalent Cl(1) atoms. Both K(2)-Cl(1) bond lengths are 2.97 Å. Na(1) is bonded in a linear geometry to two equivalent Cl(2) atoms. Both Na(1)-Cl(2) bond lengths are 2.46 Å. Fe(1) is bonded to two equivalent Cl(2) and four equivalent Cl(1) atoms to form distorted FeCl6 octahedra that share faces with two equivalent K(1)Cl6 octahedra. Both Fe(1)-Cl(2) bond lengths are 2.71 Å. All Fe(1)-Cl(1) bond lengths are 2.39 Å. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a distorted T-shaped geometry to one K(1), one K(2), and one Fe(1) atom. In the second Cl site, Cl(2) is bonded in a 3-coordinate geometry to one K(1), one Na(1), and one Fe(1) atom.