Na8Mg(FeO4)2 crystallizes in the triclinic P1 space group. There are eight inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(3), one O(4), one O(6), one O(7), and one O(8) atom. In the second Na site, Na(2) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(4), one O(7), and one O(8) atom. In the third Na site, Na(3) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form distorted NaO4 tetrahedra that share  a cornercorner with one Na(6)O5 square pyramid, corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, corners with two equivalent Mg(1)O4 trigonal pyramids, and  an edgeedge with one Mg(1)O4 trigonal pyramid. In the fourth Na site, Na(4) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(5), one O(6), and one O(8) atom. In the fifth Na site, Na(5) is bonded in a 5-coordinate geometry to one O(3), one O(4), one O(6), one O(7), and one O(8) atom. In the sixth Na site, Na(6) is bonded to one O(3), one O(4), one O(5), one O(7), and one O(8) atom to form distorted NaO5 square pyramids that share  a cornercorner with one Na(3)O4 tetrahedra,  a cornercorner with one Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra,  a cornercorner with one Mg(1)O4 trigonal pyramid, and  an edgeedge with one Fe(1)O4 tetrahedra. In the seventh Na site, Na(7) is bonded in a 4-coordinate geometry to one O(2), one O(3), one O(6), and one O(7) atom. In the eighth Na site, Na(8) is bonded in a 4-coordinate geometry to one O(1), one O(4), one O(5), and one O(8) atom. Mg(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form distorted MgO4 trigonal pyramids that share  a cornercorner with one Na(6)O5 square pyramid, corners with two equivalent Na(3)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra,  an edgeedge with one Na(3)O4 tetrahedra, and  an edgeedge with one Fe(1)O4 tetrahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), one O(4), one O(5), and one O(8) atom to form FeO4 tetrahedra that share  a cornercorner with one Na(6)O5 square pyramid, corners with two equivalent Na(3)O4 tetrahedra,  an edgeedge with one Na(6)O5 square pyramid, and  an edgeedge with one Mg(1)O4 trigonal pyramid. In the second Fe site, Fe(2) is bonded to one O(1), one O(3), one O(6), and one O(7) atom to form FeO4 tetrahedra that share corners with two equivalent Na(6)O5 square pyramids, corners with two equivalent Na(3)O4 tetrahedra, and corners with two equivalent Mg(1)O4 trigonal pyramids. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(3), one Na(4), one Na(8), one Mg(1), and one Fe(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(3), one Na(4), one Na(7), one Mg(1), and one Fe(1) atom. In the third O site, O(3) is bonded to one Na(1), one Na(2), one Na(5), one Na(6), one Na(7), and one Fe(2) atom to form a mixture of distorted edge and corner-sharing ONa5Fe octahedra. The corner-sharing octahedral tilt angles range from 13-25°. In the fourth O site, O(4) is bonded to one Na(1), one Na(2), one Na(5), one Na(6), one Na(8), and one Fe(1) atom to form edge-sharing ONa5Fe octahedra. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Na(3), one Na(4), one Na(6), one Na(8), one Mg(1), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a 7-coordinate geometry to one Na(1), one Na(3), one Na(4), one Na(5), one Na(7), one Mg(1), and one Fe(2) atom. In the seventh O site, O(7) is bonded to one Na(1), one Na(2), one Na(5), one Na(6), one Na(7), and one Fe(2) atom to form a mixture of distorted edge and corner-sharing ONa5Fe octahedra. The corner-sharing octahedral tilt angles range from 13-25°. In the eighth O site, O(8) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(4), one Na(5), one Na(6), one Na(8), and one Fe(1) atom.
Na8Mg(FeO4)2 crystallizes in the triclinic P1 space group. There are eight inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(3), one O(4), one O(6), one O(7), and one O(8) atom. The Na(1)-O(3) bond length is 2.42 Å. The Na(1)-O(4) bond length is 2.33 Å. The Na(1)-O(6) bond length is 2.39 Å. The Na(1)-O(7) bond length is 2.50 Å. The Na(1)-O(8) bond length is 2.69 Å. In the second Na site, Na(2) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(4), one O(7), and one O(8) atom. The Na(2)-O(3) bond length is 2.37 Å. The Na(2)-O(4) bond length is 2.33 Å. The Na(2)-O(7) bond length is 2.33 Å. The Na(2)-O(8) bond length is 2.40 Å. In the third Na site, Na(3) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form distorted NaO4 tetrahedra that share  a cornercorner with one Na(6)O5 square pyramid, corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, corners with two equivalent Mg(1)O4 trigonal pyramids, and  an edgeedge with one Mg(1)O4 trigonal pyramid. The Na(3)-O(1) bond length is 2.51 Å. The Na(3)-O(2) bond length is 2.32 Å. The Na(3)-O(5) bond length is 2.68 Å. The Na(3)-O(6) bond length is 2.47 Å. In the fourth Na site, Na(4) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(5), one O(6), and one O(8) atom. The Na(4)-O(1) bond length is 2.40 Å. The Na(4)-O(2) bond length is 2.23 Å. The Na(4)-O(5) bond length is 2.31 Å. The Na(4)-O(6) bond length is 2.88 Å. The Na(4)-O(8) bond length is 2.62 Å. In the fifth Na site, Na(5) is bonded in a 5-coordinate geometry to one O(3), one O(4), one O(6), one O(7), and one O(8) atom. The Na(5)-O(3) bond length is 2.33 Å. The Na(5)-O(4) bond length is 2.36 Å. The Na(5)-O(6) bond length is 2.89 Å. The Na(5)-O(7) bond length is 2.34 Å. The Na(5)-O(8) bond length is 2.72 Å. In the sixth Na site, Na(6) is bonded to one O(3), one O(4), one O(5), one O(7), and one O(8) atom to form distorted NaO5 square pyramids that share  a cornercorner with one Na(3)O4 tetrahedra,  a cornercorner with one Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra,  a cornercorner with one Mg(1)O4 trigonal pyramid, and  an edgeedge with one Fe(1)O4 tetrahedra. The Na(6)-O(3) bond length is 2.51 Å. The Na(6)-O(4) bond length is 2.44 Å. The Na(6)-O(5) bond length is 2.44 Å. The Na(6)-O(7) bond length is 2.59 Å. The Na(6)-O(8) bond length is 2.53 Å. In the seventh Na site, Na(7) is bonded in a 4-coordinate geometry to one O(2), one O(3), one O(6), and one O(7) atom. The Na(7)-O(2) bond length is 2.40 Å. The Na(7)-O(3) bond length is 2.23 Å. The Na(7)-O(6) bond length is 2.58 Å. The Na(7)-O(7) bond length is 2.18 Å. In the eighth Na site, Na(8) is bonded in a 4-coordinate geometry to one O(1), one O(4), one O(5), and one O(8) atom. The Na(8)-O(1) bond length is 2.52 Å. The Na(8)-O(4) bond length is 2.22 Å. The Na(8)-O(5) bond length is 2.40 Å. The Na(8)-O(8) bond length is 2.33 Å. Mg(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form distorted MgO4 trigonal pyramids that share  a cornercorner with one Na(6)O5 square pyramid, corners with two equivalent Na(3)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra,  an edgeedge with one Na(3)O4 tetrahedra, and  an edgeedge with one Fe(1)O4 tetrahedra. The Mg(1)-O(1) bond length is 2.00 Å. The Mg(1)-O(2) bond length is 2.00 Å. The Mg(1)-O(5) bond length is 2.07 Å. The Mg(1)-O(6) bond length is 1.98 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), one O(4), one O(5), and one O(8) atom to form FeO4 tetrahedra that share  a cornercorner with one Na(6)O5 square pyramid, corners with two equivalent Na(3)O4 tetrahedra,  an edgeedge with one Na(6)O5 square pyramid, and  an edgeedge with one Mg(1)O4 trigonal pyramid. The Fe(1)-O(2) bond length is 1.97 Å. The Fe(1)-O(4) bond length is 1.88 Å. The Fe(1)-O(5) bond length is 1.94 Å. The Fe(1)-O(8) bond length is 1.89 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(3), one O(6), and one O(7) atom to form FeO4 tetrahedra that share corners with two equivalent Na(6)O5 square pyramids, corners with two equivalent Na(3)O4 tetrahedra, and corners with two equivalent Mg(1)O4 trigonal pyramids. The Fe(2)-O(1) bond length is 1.98 Å. The Fe(2)-O(3) bond length is 1.90 Å. The Fe(2)-O(6) bond length is 1.95 Å. The Fe(2)-O(7) bond length is 1.90 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(3), one Na(4), one Na(8), one Mg(1), and one Fe(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(3), one Na(4), one Na(7), one Mg(1), and one Fe(1) atom. In the third O site, O(3) is bonded to one Na(1), one Na(2), one Na(5), one Na(6), one Na(7), and one Fe(2) atom to form a mixture of distorted edge and corner-sharing ONa5Fe octahedra. The corner-sharing octahedral tilt angles range from 13-25°. In the fourth O site, O(4) is bonded to one Na(1), one Na(2), one Na(5), one Na(6), one Na(8), and one Fe(1) atom to form edge-sharing ONa5Fe octahedra. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Na(3), one Na(4), one Na(6), one Na(8), one Mg(1), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a 7-coordinate geometry to one Na(1), one Na(3), one Na(4), one Na(5), one Na(7), one Mg(1), and one Fe(2) atom. In the seventh O site, O(7) is bonded to one Na(1), one Na(2), one Na(5), one Na(6), one Na(7), and one Fe(2) atom to form a mixture of distorted edge and corner-sharing ONa5Fe octahedra. The corner-sharing octahedral tilt angles range from 13-25°. In the eighth O site, O(8) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(4), one Na(5), one Na(6), one Na(8), and one Fe(1) atom.