Na3(CoO2)4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(3) and four equivalent O(2) atoms. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(3), and four equivalent O(2) atoms to form edge-sharing CoO6 octahedra. In the second Co site, Co(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form edge-sharing CoO6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), one Co(1), and two equivalent Co(2) atoms to form ONa2Co3 square pyramids that share corners with three equivalent O(3)Na3Co3 octahedra, corners with two equivalent O(1)Na2Co3 square pyramids, corners with four equivalent O(2)Na2Co3 square pyramids, edges with three equivalent O(3)Na3Co3 octahedra,  an edgeedge with one O(1)Na2Co3 square pyramid, and edges with four equivalent O(2)Na2Co3 square pyramids. The corner-sharing octahedral tilt angles range from 1-2°. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Co(2), and two equivalent Co(1) atoms to form ONa2Co3 square pyramids that share corners with two equivalent O(1)Na2Co3 square pyramids, corners with seven equivalent O(2)Na2Co3 square pyramids, edges with four equivalent O(3)Na3Co3 octahedra, edges with two equivalent O(1)Na2Co3 square pyramids, and edges with two equivalent O(2)Na2Co3 square pyramids. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Co(1), and two equivalent Co(2) atoms to form distorted ONa3Co3 octahedra that share corners with three equivalent O(3)Na3Co3 octahedra, corners with three equivalent O(1)Na2Co3 square pyramids,  an edgeedge with one O(3)Na3Co3 octahedra, edges with three equivalent O(1)Na2Co3 square pyramids, and edges with eight equivalent O(2)Na2Co3 square pyramids. The corner-sharing octahedra are not tilted.
Na3(CoO2)4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Both Na(1)-O(1) bond lengths are 2.31 Å. Both Na(1)-O(2) bond lengths are 2.38 Å. Both Na(1)-O(3) bond lengths are 2.49 Å. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(3) and four equivalent O(2) atoms. Both Na(2)-O(3) bond lengths are 2.41 Å. All Na(2)-O(2) bond lengths are 2.35 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(3), and four equivalent O(2) atoms to form edge-sharing CoO6 octahedra. The Co(1)-O(1) bond length is 1.90 Å. The Co(1)-O(3) bond length is 1.95 Å. There are two shorter (1.97 Å) and two longer (2.01 Å) Co(1)-O(2) bond lengths. In the second Co site, Co(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form edge-sharing CoO6 octahedra. Both Co(2)-O(1) bond lengths are 2.02 Å. Both Co(2)-O(2) bond lengths are 1.97 Å. Both Co(2)-O(3) bond lengths are 1.95 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), one Co(1), and two equivalent Co(2) atoms to form ONa2Co3 square pyramids that share corners with three equivalent O(3)Na3Co3 octahedra, corners with two equivalent O(1)Na2Co3 square pyramids, corners with four equivalent O(2)Na2Co3 square pyramids, edges with three equivalent O(3)Na3Co3 octahedra,  an edgeedge with one O(1)Na2Co3 square pyramid, and edges with four equivalent O(2)Na2Co3 square pyramids. The corner-sharing octahedral tilt angles range from 1-2°. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Co(2), and two equivalent Co(1) atoms to form ONa2Co3 square pyramids that share corners with two equivalent O(1)Na2Co3 square pyramids, corners with seven equivalent O(2)Na2Co3 square pyramids, edges with four equivalent O(3)Na3Co3 octahedra, edges with two equivalent O(1)Na2Co3 square pyramids, and edges with two equivalent O(2)Na2Co3 square pyramids. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Co(1), and two equivalent Co(2) atoms to form distorted ONa3Co3 octahedra that share corners with three equivalent O(3)Na3Co3 octahedra, corners with three equivalent O(1)Na2Co3 square pyramids,  an edgeedge with one O(3)Na3Co3 octahedra, edges with three equivalent O(1)Na2Co3 square pyramids, and edges with eight equivalent O(2)Na2Co3 square pyramids. The corner-sharing octahedra are not tilted.