Na5CoO4 crystallizes in the orthorhombic Pmn2_1 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(2), and two equivalent O(3) atoms. In the second Na site, Na(2) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form distorted NaO4 tetrahedra that share corners with two equivalent Na(3)O4 tetrahedra, corners with two equivalent Co(1)O4 tetrahedra, corners with four equivalent Na(2)O4 tetrahedra,  an edgeedge with one Na(3)O4 tetrahedra, and  an edgeedge with one Co(1)O4 tetrahedra. In the third Na site, Na(3) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form distorted NaO4 tetrahedra that share corners with four equivalent Na(2)O4 tetrahedra, corners with four equivalent Co(1)O4 tetrahedra, and edges with two equivalent Na(2)O4 tetrahedra. 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 four equivalent Na(2)O4 tetrahedra, corners with four equivalent Na(3)O4 tetrahedra, and edges with two equivalent Na(2)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Co(1) atom to form a mixture of distorted edge and corner-sharing ONa5Co pentagonal pyramids. The corner-sharing octahedral tilt angles range from 69-71°. In the second O site, O(2) is bonded in a 8-coordinate geometry to one Na(3), two equivalent Na(2), four equivalent Na(1), and one Co(1) atom. In the third O site, O(3) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Co(1) atom to form a mixture of edge and corner-sharing ONa5Co octahedra. The corner-sharing octahedral tilt angles range from 40-53°.
Na5CoO4 crystallizes in the orthorhombic Pmn2_1 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(2), and two equivalent O(3) atoms. The Na(1)-O(1) bond length is 2.37 Å. There is one shorter (2.64 Å) and one longer (2.71 Å) Na(1)-O(2) bond length. There is one shorter (2.32 Å) and one longer (2.39 Å) Na(1)-O(3) bond length. In the second Na site, Na(2) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form distorted NaO4 tetrahedra that share corners with two equivalent Na(3)O4 tetrahedra, corners with two equivalent Co(1)O4 tetrahedra, corners with four equivalent Na(2)O4 tetrahedra,  an edgeedge with one Na(3)O4 tetrahedra, and  an edgeedge with one Co(1)O4 tetrahedra. The Na(2)-O(1) bond length is 2.46 Å. The Na(2)-O(2) bond length is 2.37 Å. There is one shorter (2.27 Å) and one longer (2.30 Å) Na(2)-O(3) bond length. In the third Na site, Na(3) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form distorted NaO4 tetrahedra that share corners with four equivalent Na(2)O4 tetrahedra, corners with four equivalent Co(1)O4 tetrahedra, and edges with two equivalent Na(2)O4 tetrahedra. The Na(3)-O(1) bond length is 2.55 Å. The Na(3)-O(2) bond length is 2.40 Å. Both Na(3)-O(3) bond lengths are 2.33 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 four equivalent Na(2)O4 tetrahedra, corners with four equivalent Na(3)O4 tetrahedra, and edges with two equivalent Na(2)O4 tetrahedra. The Co(1)-O(1) bond length is 1.88 Å. The Co(1)-O(2) bond length is 1.93 Å. Both Co(1)-O(3) bond lengths are 1.89 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Co(1) atom to form a mixture of distorted edge and corner-sharing ONa5Co pentagonal pyramids. The corner-sharing octahedral tilt angles range from 69-71°. In the second O site, O(2) is bonded in a 8-coordinate geometry to one Na(3), two equivalent Na(2), four equivalent Na(1), and one Co(1) atom. In the third O site, O(3) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Co(1) atom to form a mixture of edge and corner-sharing ONa5Co octahedra. The corner-sharing octahedral tilt angles range from 40-53°.