Na6Mg(CoO3)2 crystallizes in the triclinic P-1 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted NaO4 tetrahedra that share corners with three equivalent Co(1)O4 tetrahedra,  an edgeedge with one Na(1)O4 tetrahedra, and  an edgeedge with one Co(1)O4 tetrahedra. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(1), and two equivalent O(3) atoms. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to one O(1), one O(3), and two equivalent O(2) atoms. Mg(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Co(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form distorted CoO4 tetrahedra that share corners with three equivalent Na(1)O4 tetrahedra,  an edgeedge with one Na(1)O4 tetrahedra, and  an edgeedge with one Co(1)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 7-coordinate geometry to one Na(3), two equivalent Na(1), two equivalent Na(2), one Mg(1), and one Co(1) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), two equivalent Na(3), one Mg(1), and one Co(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Na(1), one Na(3), two equivalent Na(2), and two equivalent Co(1) atoms.
Na6Mg(CoO3)2 crystallizes in the triclinic P-1 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted NaO4 tetrahedra that share corners with three equivalent Co(1)O4 tetrahedra,  an edgeedge with one Na(1)O4 tetrahedra, and  an edgeedge with one Co(1)O4 tetrahedra. The Na(1)-O(2) bond length is 2.33 Å. The Na(1)-O(3) bond length is 2.35 Å. There is one shorter (2.37 Å) and one longer (2.40 Å) Na(1)-O(1) bond length. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(1), and two equivalent O(3) atoms. The Na(2)-O(2) bond length is 2.42 Å. There is one shorter (2.44 Å) and one longer (2.65 Å) Na(2)-O(1) bond length. There is one shorter (2.36 Å) and one longer (2.78 Å) Na(2)-O(3) bond length. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to one O(1), one O(3), and two equivalent O(2) atoms. The Na(3)-O(1) bond length is 2.37 Å. The Na(3)-O(3) bond length is 2.28 Å. There is one shorter (2.25 Å) and one longer (2.63 Å) Na(3)-O(2) bond length. Mg(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Mg(1)-O(1) bond lengths are 2.09 Å. Both Mg(1)-O(2) bond lengths are 2.04 Å. Co(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form distorted CoO4 tetrahedra that share corners with three equivalent Na(1)O4 tetrahedra,  an edgeedge with one Na(1)O4 tetrahedra, and  an edgeedge with one Co(1)O4 tetrahedra. The Co(1)-O(1) bond length is 2.02 Å. The Co(1)-O(2) bond length is 1.98 Å. There is one shorter (2.02 Å) and one longer (2.05 Å) Co(1)-O(3) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 7-coordinate geometry to one Na(3), two equivalent Na(1), two equivalent Na(2), one Mg(1), and one Co(1) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), two equivalent Na(3), one Mg(1), and one Co(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Na(1), one Na(3), two equivalent Na(2), and two equivalent Co(1) atoms.