Na(FeO2)2 crystallizes in the orthorhombic Pmm2 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(3) and four equivalent O(1) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. In the third Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. In the fourth Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(3) and four equivalent O(1) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2); one O(3); and four O(1,1) atoms to form edge-sharing FeO6 octahedra. In the second Fe site, Fe(1) is bonded to one O(2); one O(3); and four O(1,1) atoms to form edge-sharing FeO6 octahedra. In the third Fe site, Fe(2) is bonded to two O(1,1); two O(2,2); and two O(3,3) atoms to form edge-sharing FeO6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Na(1); one Na(2); one Fe(2); and two Fe(1,1) atoms to form distorted ONa2Fe3 trigonal bipyramids that share corners with five O(1,1)Na2Fe3 trigonal bipyramids; corners with two equivalent O(3)NaFe3 trigonal pyramids; edges with four O(1,1)Na2Fe3 trigonal bipyramids; and edges with two O(3,3)NaFe3 trigonal pyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Na(2), one Fe(1), and two equivalent Fe(2) atoms. In the third O site, O(3) is bonded to one Na(1), one Fe(1), and two equivalent Fe(2) atoms to form ONaFe3 trigonal pyramids that share corners with four equivalent O(1)Na2Fe3 trigonal bipyramids; corners with three O(3,3)NaFe3 trigonal pyramids; and edges with four O(1,1)Na2Fe3 trigonal bipyramids. In the fourth O site, O(3) is bonded to one Na(1), one Fe(1), and two equivalent Fe(2) atoms to form ONaFe3 trigonal pyramids that share corners with four equivalent O(1)Na2Fe3 trigonal bipyramids; corners with three O(3,3)NaFe3 trigonal pyramids; and edges with four O(1,1)Na2Fe3 trigonal bipyramids. In the fifth O site, O(2) is bonded in a rectangular see-saw-like geometry to one Na(2), one Fe(1), and two equivalent Fe(2) atoms. In the sixth O site, O(1) is bonded to one Na(1); one Na(2); one Fe(2); and two Fe(1,1) atoms to form distorted ONa2Fe3 trigonal bipyramids that share corners with five O(1,1)Na2Fe3 trigonal bipyramids; corners with two equivalent O(3)NaFe3 trigonal pyramids; edges with four O(1,1)Na2Fe3 trigonal bipyramids; and edges with two O(3,3)NaFe3 trigonal pyramids.
Na(FeO2)2 crystallizes in the orthorhombic Pmm2 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(3) and four equivalent O(1) atoms. Both Na(1)-O(3) bond lengths are 2.37 Å. All Na(1)-O(1) bond lengths are 2.49 Å. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. Both Na(2)-O(2) bond lengths are 2.36 Å. All Na(2)-O(1) bond lengths are 2.49 Å. In the third Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. Both Na(2)-O(2) bond lengths are 2.35 Å. All Na(2)-O(1) bond lengths are 2.49 Å. In the fourth Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(3) and four equivalent O(1) atoms. Both Na(1)-O(3) bond lengths are 2.37 Å. All Na(1)-O(1) bond lengths are 2.49 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2); one O(3); and four O(1,1) atoms to form edge-sharing FeO6 octahedra. The Fe(1)-O(2) bond length is 1.91 Å. The Fe(1)-O(3) bond length is 1.92 Å. There are two shorter (1.92 Å) and two longer (1.94 Å) Fe(1)-O(1,1) bond lengths. In the second Fe site, Fe(1) is bonded to one O(2); one O(3); and four O(1,1) atoms to form edge-sharing FeO6 octahedra. The Fe(1)-O(2) bond length is 1.90 Å. The Fe(1)-O(3) bond length is 1.92 Å. There are two shorter (1.91 Å) and two longer (1.94 Å) Fe(1)-O(1,1) bond lengths. In the third Fe site, Fe(2) is bonded to two O(1,1); two O(2,2); and two O(3,3) atoms to form edge-sharing FeO6 octahedra. Both Fe(2)-O(1,1) bond lengths are 1.93 Å. Both Fe(2)-O(2,2) bond lengths are 1.92 Å. There is one shorter (1.91 Å) and one longer (1.92 Å) Fe(2)-O(3,3) bond length. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Na(1); one Na(2); one Fe(2); and two Fe(1,1) atoms to form distorted ONa2Fe3 trigonal bipyramids that share corners with five O(1,1)Na2Fe3 trigonal bipyramids; corners with two equivalent O(3)NaFe3 trigonal pyramids; edges with four O(1,1)Na2Fe3 trigonal bipyramids; and edges with two O(3,3)NaFe3 trigonal pyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Na(2), one Fe(1), and two equivalent Fe(2) atoms. In the third O site, O(3) is bonded to one Na(1), one Fe(1), and two equivalent Fe(2) atoms to form ONaFe3 trigonal pyramids that share corners with four equivalent O(1)Na2Fe3 trigonal bipyramids; corners with three O(3,3)NaFe3 trigonal pyramids; and edges with four O(1,1)Na2Fe3 trigonal bipyramids. In the fourth O site, O(3) is bonded to one Na(1), one Fe(1), and two equivalent Fe(2) atoms to form ONaFe3 trigonal pyramids that share corners with four equivalent O(1)Na2Fe3 trigonal bipyramids; corners with three O(3,3)NaFe3 trigonal pyramids; and edges with four O(1,1)Na2Fe3 trigonal bipyramids. In the fifth O site, O(2) is bonded in a rectangular see-saw-like geometry to one Na(2), one Fe(1), and two equivalent Fe(2) atoms. In the sixth O site, O(1) is bonded to one Na(1); one Na(2); one Fe(2); and two Fe(1,1) atoms to form distorted ONa2Fe3 trigonal bipyramids that share corners with five O(1,1)Na2Fe3 trigonal bipyramids; corners with two equivalent O(3)NaFe3 trigonal pyramids; edges with four O(1,1)Na2Fe3 trigonal bipyramids; and edges with two O(3,3)NaFe3 trigonal pyramids.