Na(FeO2)2 crystallizes in the triclinic P-1 space group. Na(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(2) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form edge-sharing FeO6 octahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form edge-sharing FeO6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Fe(2), and two equivalent Fe(1) atoms. In the second O site, O(2) is bonded to two equivalent Na(1), one Fe(1), and two equivalent Fe(2) atoms to form a mixture of distorted corner and edge-sharing ONa2Fe3 square pyramids.
Na(FeO2)2 crystallizes in the triclinic P-1 space group. Na(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(2) atoms. Both Na(1)-O(1) bond lengths are 2.42 Å. There are two shorter (2.42 Å) and two longer (2.53 Å) Na(1)-O(2) bond lengths. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form edge-sharing FeO6 octahedra. Both Fe(1)-O(2) bond lengths are 1.93 Å. There are two shorter (1.91 Å) and two longer (2.13 Å) Fe(1)-O(1) bond lengths. In the second Fe site, Fe(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form edge-sharing FeO6 octahedra. Both Fe(2)-O(1) bond lengths are 2.03 Å. There are two shorter (2.05 Å) and two longer (2.08 Å) Fe(2)-O(2) bond lengths. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Fe(2), and two equivalent Fe(1) atoms. In the second O site, O(2) is bonded to two equivalent Na(1), one Fe(1), and two equivalent Fe(2) atoms to form a mixture of distorted corner and edge-sharing ONa2Fe3 square pyramids.