K2FeO4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 3-coordinate geometry to one O(2), one O(3), and one O(4) atom. In the second K site, K(2) is bonded in a 7-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. Fe(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to two equivalent K(2) and one Fe(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), one K(2), and one Fe(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), and one Fe(1) atom.
K2FeO4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 3-coordinate geometry to one O(2), one O(3), and one O(4) atom. The K(1)-O(2) bond length is 2.70 Å. The K(1)-O(3) bond length is 2.76 Å. The K(1)-O(4) bond length is 2.83 Å. In the second K site, K(2) is bonded in a 7-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. The K(2)-O(2) bond length is 2.85 Å. There is one shorter (3.12 Å) and one longer (3.27 Å) K(2)-O(1) bond length. Both K(2)-O(3) bond lengths are 2.77 Å. There is one shorter (2.71 Å) and one longer (2.74 Å) K(2)-O(4) bond length. Fe(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Fe(1)-O(1) bond length is 1.66 Å. The Fe(1)-O(2) bond length is 1.66 Å. The Fe(1)-O(3) bond length is 1.67 Å. The Fe(1)-O(4) bond length is 1.67 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to two equivalent K(2) and one Fe(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), one K(2), and one Fe(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), and one Fe(1) atom.