Na2Co6O7 crystallizes in the tetragonal P4_2nm space group. Na(1) is bonded in a 1-coordinate geometry to one O(1) and four equivalent O(2) atoms. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(3) and three equivalent O(2) atoms to form corner-sharing CoO4 tetrahedra. In the second Co site, Co(2) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(2), and two equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Na(1) and two equivalent Co(2) atoms. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Na(1), one Co(2), and three equivalent Co(1) atoms. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to two equivalent Co(1) and two equivalent Co(2) atoms.
Na2Co6O7 crystallizes in the tetragonal P4_2nm space group. Na(1) is bonded in a 1-coordinate geometry to one O(1) and four equivalent O(2) atoms. The Na(1)-O(1) bond length is 2.41 Å. There are two shorter (2.79 Å) and two longer (2.80 Å) Na(1)-O(2) bond lengths. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(3) and three equivalent O(2) atoms to form corner-sharing CoO4 tetrahedra. The Co(1)-O(3) bond length is 2.00 Å. There is one shorter (1.97 Å) and two longer (1.99 Å) Co(1)-O(2) bond lengths. In the second Co site, Co(2) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(2), and two equivalent O(3) atoms. The Co(2)-O(1) bond length is 1.88 Å. Both Co(2)-O(2) bond lengths are 2.44 Å. There is one shorter (1.99 Å) and one longer (2.02 Å) Co(2)-O(3) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Na(1) and two equivalent Co(2) atoms. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Na(1), one Co(2), and three equivalent Co(1) atoms. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to two equivalent Co(1) and two equivalent Co(2) atoms.