Na8Mg(CoO4)2 crystallizes in the triclinic P1 space group. There are eight inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(8) atom to form distorted NaO5 square pyramids that share  a cornercorner with one Na(5)O4 tetrahedra,  a cornercorner with one Co(2)O4 tetrahedra, corners with three equivalent Mg(1)O4 tetrahedra,  an edgeedge with one Na(5)O4 tetrahedra,  an edgeedge with one Co(1)O4 tetrahedra, and  an edgeedge with one Co(2)O4 tetrahedra. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(1), one O(4), one O(5), one O(6), and one O(7) 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 in a 4-coordinate geometry to one O(4), one O(5), one O(6), and one O(7) atom. In the fifth Na site, Na(5) is bonded to one O(2), one O(3), one O(4), and one O(7) atom to form distorted NaO4 tetrahedra that share  a cornercorner with one Na(1)O5 square pyramid,  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Co(1)O4 tetrahedra, corners with three equivalent Co(2)O4 tetrahedra, and  an edgeedge with one Na(1)O5 square pyramid. In the sixth Na site, Na(6) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(6), and one O(8) atom. In the seventh Na site, Na(7) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), one O(6), and one O(8) atom. In the eighth Na site, Na(8) is bonded in a distorted rectangular see-saw-like geometry to one O(4), one O(5), one O(6), and one O(7) atom. Mg(1) is bonded to one O(1), one O(3), one O(6), and one O(8) atom to form MgO4 tetrahedra that share corners with three equivalent Na(1)O5 square pyramids,  a cornercorner with one Na(5)O4 tetrahedra,  a cornercorner with one Co(2)O4 tetrahedra, and corners with three equivalent Co(1)O4 tetrahedra. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(6), one O(7), and one O(8) atom to form CoO4 tetrahedra that share  a cornercorner with one Na(5)O4 tetrahedra, corners with three equivalent Mg(1)O4 tetrahedra, and  an edgeedge with one Na(1)O5 square pyramid. In the second Co site, Co(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form CoO4 tetrahedra that share  a cornercorner with one Na(1)O5 square pyramid,  a cornercorner with one Mg(1)O4 tetrahedra, corners with three equivalent Na(5)O4 tetrahedra, and  an edgeedge with one Na(1)O5 square pyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(6), one Na(7), one Mg(1), and one Co(1) atom. In the second O site, O(2) is bonded to one Na(1), one Na(3), one Na(5), one Na(6), one Na(7), and one Co(2) atom to form corner-sharing ONa5Co octahedra. In the third O site, O(3) is bonded in a 7-coordinate geometry to one Na(1), one Na(3), one Na(5), one Na(6), one Na(7), one Mg(1), and one Co(2) atom. In the fourth O site, O(4) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(4), one Na(5), one Na(8), and one Co(2) atom. In the fifth O site, O(5) is bonded to one Na(2), one Na(3), one Na(4), one Na(8), and one Co(2) atom to form corner-sharing ONa4Co trigonal bipyramids. The corner-sharing octahedral tilt angles range from 44-69°. In the sixth O site, O(6) is bonded in a 7-coordinate geometry to one Na(2), one Na(4), one Na(6), one Na(7), one Na(8), one Mg(1), and one Co(1) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Na(2), one Na(4), one Na(5), one Na(8), and one Co(1) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Na(1), one Na(6), one Na(7), one Mg(1), and one Co(1) atom.
Na8Mg(CoO4)2 crystallizes in the triclinic P1 space group. There are eight inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(8) atom to form distorted NaO5 square pyramids that share  a cornercorner with one Na(5)O4 tetrahedra,  a cornercorner with one Co(2)O4 tetrahedra, corners with three equivalent Mg(1)O4 tetrahedra,  an edgeedge with one Na(5)O4 tetrahedra,  an edgeedge with one Co(1)O4 tetrahedra, and  an edgeedge with one Co(2)O4 tetrahedra. The Na(1)-O(1) bond length is 2.75 Å. The Na(1)-O(2) bond length is 2.41 Å. The Na(1)-O(3) bond length is 2.73 Å. The Na(1)-O(4) bond length is 2.52 Å. The Na(1)-O(8) bond length is 2.42 Å. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(1), one O(4), one O(5), one O(6), and one O(7) atom. The Na(2)-O(1) bond length is 2.46 Å. The Na(2)-O(4) bond length is 2.75 Å. The Na(2)-O(5) bond length is 2.27 Å. The Na(2)-O(6) bond length is 2.56 Å. The Na(2)-O(7) bond length is 2.34 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 2.27 Å. The Na(3)-O(3) bond length is 2.38 Å. The Na(3)-O(4) bond length is 2.32 Å. The Na(3)-O(5) bond length is 2.32 Å. In the fourth Na site, Na(4) is bonded in a 4-coordinate geometry to one O(4), one O(5), one O(6), and one O(7) atom. The Na(4)-O(4) bond length is 2.47 Å. The Na(4)-O(5) bond length is 2.25 Å. The Na(4)-O(6) bond length is 2.37 Å. The Na(4)-O(7) bond length is 2.56 Å. In the fifth Na site, Na(5) is bonded to one O(2), one O(3), one O(4), and one O(7) atom to form distorted NaO4 tetrahedra that share  a cornercorner with one Na(1)O5 square pyramid,  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Co(1)O4 tetrahedra, corners with three equivalent Co(2)O4 tetrahedra, and  an edgeedge with one Na(1)O5 square pyramid. The Na(5)-O(2) bond length is 2.28 Å. The Na(5)-O(3) bond length is 2.72 Å. The Na(5)-O(4) bond length is 2.43 Å. The Na(5)-O(7) bond length is 2.33 Å. In the sixth Na site, Na(6) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(6), and one O(8) atom. The Na(6)-O(1) bond length is 2.81 Å. The Na(6)-O(2) bond length is 2.25 Å. The Na(6)-O(3) bond length is 2.51 Å. The Na(6)-O(6) bond length is 2.41 Å. The Na(6)-O(8) bond length is 2.29 Å. In the seventh Na site, Na(7) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), one O(6), and one O(8) atom. The Na(7)-O(1) bond length is 2.26 Å. The Na(7)-O(2) bond length is 2.24 Å. The Na(7)-O(3) bond length is 2.40 Å. The Na(7)-O(6) bond length is 2.73 Å. The Na(7)-O(8) bond length is 2.50 Å. In the eighth Na site, Na(8) is bonded in a distorted rectangular see-saw-like geometry to one O(4), one O(5), one O(6), and one O(7) atom. The Na(8)-O(4) bond length is 2.36 Å. The Na(8)-O(5) bond length is 2.40 Å. The Na(8)-O(6) bond length is 2.51 Å. The Na(8)-O(7) bond length is 2.38 Å. Mg(1) is bonded to one O(1), one O(3), one O(6), and one O(8) atom to form MgO4 tetrahedra that share corners with three equivalent Na(1)O5 square pyramids,  a cornercorner with one Na(5)O4 tetrahedra,  a cornercorner with one Co(2)O4 tetrahedra, and corners with three equivalent Co(1)O4 tetrahedra. The Mg(1)-O(1) bond length is 1.95 Å. The Mg(1)-O(3) bond length is 2.03 Å. The Mg(1)-O(6) bond length is 2.02 Å. The Mg(1)-O(8) bond length is 1.96 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(6), one O(7), and one O(8) atom to form CoO4 tetrahedra that share  a cornercorner with one Na(5)O4 tetrahedra, corners with three equivalent Mg(1)O4 tetrahedra, and  an edgeedge with one Na(1)O5 square pyramid. The Co(1)-O(1) bond length is 1.95 Å. The Co(1)-O(6) bond length is 1.95 Å. The Co(1)-O(7) bond length is 1.82 Å. The Co(1)-O(8) bond length is 1.89 Å. In the second Co site, Co(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form CoO4 tetrahedra that share  a cornercorner with one Na(1)O5 square pyramid,  a cornercorner with one Mg(1)O4 tetrahedra, corners with three equivalent Na(5)O4 tetrahedra, and  an edgeedge with one Na(1)O5 square pyramid. The Co(2)-O(2) bond length is 1.91 Å. The Co(2)-O(3) bond length is 1.96 Å. The Co(2)-O(4) bond length is 1.87 Å. The Co(2)-O(5) bond length is 1.85 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(6), one Na(7), one Mg(1), and one Co(1) atom. In the second O site, O(2) is bonded to one Na(1), one Na(3), one Na(5), one Na(6), one Na(7), and one Co(2) atom to form corner-sharing ONa5Co octahedra. In the third O site, O(3) is bonded in a 7-coordinate geometry to one Na(1), one Na(3), one Na(5), one Na(6), one Na(7), one Mg(1), and one Co(2) atom. In the fourth O site, O(4) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(4), one Na(5), one Na(8), and one Co(2) atom. In the fifth O site, O(5) is bonded to one Na(2), one Na(3), one Na(4), one Na(8), and one Co(2) atom to form corner-sharing ONa4Co trigonal bipyramids. The corner-sharing octahedral tilt angles range from 44-69°. In the sixth O site, O(6) is bonded in a 7-coordinate geometry to one Na(2), one Na(4), one Na(6), one Na(7), one Na(8), one Mg(1), and one Co(1) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Na(2), one Na(4), one Na(5), one Na(8), and one Co(1) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Na(1), one Na(6), one Na(7), one Mg(1), and one Co(1) atom.