Na4Mg(CoO3)2 crystallizes in the monoclinic C2/m space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 3-coordinate geometry to one O(1) and two equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a distorted square co-planar geometry to two equivalent O(1) and four equivalent O(2) atoms. In the third Na site, Na(3) is bonded in a distorted octahedral geometry to two equivalent O(1) and four equivalent O(2) atoms. Mg(1) is bonded in a square co-planar geometry to four equivalent O(2) atoms. Co(1) is bonded in a distorted trigonal planar geometry to one O(1) and two equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Na(3), and one Co(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 Co(1) atom.
Na4Mg(CoO3)2 crystallizes in the monoclinic C2/m space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 3-coordinate geometry to one O(1) and two equivalent O(2) atoms. The Na(1)-O(1) bond length is 2.31 Å. Both Na(1)-O(2) bond lengths are 2.34 Å. In the second Na site, Na(2) is bonded in a distorted square co-planar geometry to two equivalent O(1) and four equivalent O(2) atoms. Both Na(2)-O(1) bond lengths are 2.93 Å. All Na(2)-O(2) bond lengths are 2.27 Å. In the third Na site, Na(3) is bonded in a distorted octahedral geometry to two equivalent O(1) and four equivalent O(2) atoms. Both Na(3)-O(1) bond lengths are 2.35 Å. All Na(3)-O(2) bond lengths are 2.74 Å. Mg(1) is bonded in a square co-planar geometry to four equivalent O(2) atoms. All Mg(1)-O(2) bond lengths are 2.05 Å. Co(1) is bonded in a distorted trigonal planar geometry to one O(1) and two equivalent O(2) atoms. The Co(1)-O(1) bond length is 1.72 Å. Both Co(1)-O(2) bond lengths are 1.81 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Na(3), and one Co(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 Co(1) atom.