Na(FeO2)2 is Spinel structured and crystallizes in the orthorhombic Imma space group. Na(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form NaO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra and corners with six equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-65°. 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 FeO6 octahedra that share corners with six equivalent Na(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with four equivalent Fe(2)O6 octahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form FeO6 octahedra that share corners with six equivalent Na(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Fe(2), and two equivalent Fe(1) atoms to form a mixture of edge and corner-sharing ONaFe3 tetrahedra. In the second O site, O(2) is bonded to one Na(1), one Fe(1), and two equivalent Fe(2) atoms to form a mixture of distorted edge and corner-sharing ONaFe3 tetrahedra.
Na(FeO2)2 is Spinel structured and crystallizes in the orthorhombic Imma space group. Na(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form NaO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra and corners with six equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-65°. Both Na(1)-O(1) bond lengths are 2.15 Å. Both Na(1)-O(2) bond lengths are 2.18 Å. 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 FeO6 octahedra that share corners with six equivalent Na(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with four equivalent Fe(2)O6 octahedra. Both Fe(1)-O(2) bond lengths are 2.07 Å. All Fe(1)-O(1) bond lengths are 2.05 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form FeO6 octahedra that share corners with six equivalent Na(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. Both Fe(2)-O(1) bond lengths are 1.93 Å. All Fe(2)-O(2) bond lengths are 1.97 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Fe(2), and two equivalent Fe(1) atoms to form a mixture of edge and corner-sharing ONaFe3 tetrahedra. In the second O site, O(2) is bonded to one Na(1), one Fe(1), and two equivalent Fe(2) atoms to form a mixture of distorted edge and corner-sharing ONaFe3 tetrahedra.