Na4Mg(FeO3)2 crystallizes in the triclinic P1 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(4), and one O(5) atom. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(6) atom. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to one O(2), one O(3), one O(4), and one O(5) atom. In the fourth Na site, Na(4) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form distorted NaO4 trigonal pyramids that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. Mg(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form distorted MgO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra,  a cornercorner with one Na(4)O4 trigonal pyramid, and  an edgeedge with one Na(4)O4 trigonal pyramid. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form FeO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, and corners with three equivalent Na(4)O4 trigonal pyramids. In the second Fe site, Fe(2) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form FeO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, and corners with two equivalent Na(4)O4 trigonal pyramids. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(4), one Mg(1), and one Fe(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(3), one Mg(1), and one Fe(2) atom. In the third O site, O(3) is bonded to one Na(2), one Na(3), one Na(4), one Mg(1), and one Fe(1) atom to form distorted edge-sharing ONa3MgFe square pyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Na(1), one Na(3), one Na(4), one Mg(1), and one Fe(2) atom. In the fifth O site, O(5) is bonded to one Na(1), one Na(3), one Fe(1), and one Fe(2) atom to form distorted edge-sharing ONa2Fe2 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), one Na(4), one Fe(1), and one Fe(2) atom.
Na4Mg(FeO3)2 crystallizes in the triclinic P1 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(4), and one O(5) atom. The Na(1)-O(1) bond length is 2.30 Å. The Na(1)-O(2) bond length is 2.45 Å. The Na(1)-O(4) bond length is 2.32 Å. The Na(1)-O(5) bond length is 2.23 Å. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(6) atom. The Na(2)-O(1) bond length is 2.34 Å. The Na(2)-O(2) bond length is 2.26 Å. The Na(2)-O(3) bond length is 2.19 Å. The Na(2)-O(6) bond length is 2.27 Å. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to one O(2), one O(3), one O(4), and one O(5) atom. The Na(3)-O(2) bond length is 2.49 Å. The Na(3)-O(3) bond length is 2.28 Å. The Na(3)-O(4) bond length is 2.29 Å. The Na(3)-O(5) bond length is 2.49 Å. In the fourth Na site, Na(4) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form distorted NaO4 trigonal pyramids that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. The Na(4)-O(1) bond length is 2.56 Å. The Na(4)-O(3) bond length is 2.39 Å. The Na(4)-O(4) bond length is 2.41 Å. The Na(4)-O(6) bond length is 2.46 Å. Mg(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form distorted MgO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra,  a cornercorner with one Na(4)O4 trigonal pyramid, and  an edgeedge with one Na(4)O4 trigonal pyramid. The Mg(1)-O(1) bond length is 2.01 Å. The Mg(1)-O(2) bond length is 1.97 Å. The Mg(1)-O(3) bond length is 2.10 Å. The Mg(1)-O(4) bond length is 2.05 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form FeO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, and corners with three equivalent Na(4)O4 trigonal pyramids. The Fe(1)-O(1) bond length is 1.90 Å. The Fe(1)-O(3) bond length is 1.90 Å. The Fe(1)-O(5) bond length is 1.95 Å. The Fe(1)-O(6) bond length is 1.96 Å. In the second Fe site, Fe(2) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form FeO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, and corners with two equivalent Na(4)O4 trigonal pyramids. The Fe(2)-O(2) bond length is 1.91 Å. The Fe(2)-O(4) bond length is 1.89 Å. The Fe(2)-O(5) bond length is 1.90 Å. The Fe(2)-O(6) bond length is 1.98 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(4), one Mg(1), and one Fe(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(3), one Mg(1), and one Fe(2) atom. In the third O site, O(3) is bonded to one Na(2), one Na(3), one Na(4), one Mg(1), and one Fe(1) atom to form distorted edge-sharing ONa3MgFe square pyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Na(1), one Na(3), one Na(4), one Mg(1), and one Fe(2) atom. In the fifth O site, O(5) is bonded to one Na(1), one Na(3), one Fe(1), and one Fe(2) atom to form distorted edge-sharing ONa2Fe2 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), one Na(4), one Fe(1), and one Fe(2) atom.