NaCo2O4 crystallizes in the triclinic P1 space group. Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form edge-sharing CoO6 octahedra. In the second Co site, Co(2) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms to form edge-sharing CoO6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Na(1), one Co(2), and two equivalent Co(1) atoms. In the second O site, O(2) is bonded to two equivalent Na(1), one Co(1), and two equivalent Co(2) atoms to form a mixture of distorted corner and edge-sharing ONa2Co3 square pyramids. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Co(2), and two equivalent Co(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Na(1), one Co(1), and two equivalent Co(2) atoms to form a mixture of distorted corner and edge-sharing ONa2Co3 trigonal bipyramids.
NaCo2O4 crystallizes in the triclinic P1 space group. Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms. The Na(1)-O(1) bond length is 2.39 Å. The Na(1)-O(3) bond length is 2.54 Å. There is one shorter (2.38 Å) and one longer (2.49 Å) Na(1)-O(2) bond length. There is one shorter (2.43 Å) and one longer (2.46 Å) Na(1)-O(4) bond length. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form edge-sharing CoO6 octahedra. The Co(1)-O(2) bond length is 1.95 Å. The Co(1)-O(4) bond length is 1.91 Å. There is one shorter (1.84 Å) and one longer (2.20 Å) Co(1)-O(1) bond length. There is one shorter (1.78 Å) and one longer (2.20 Å) Co(1)-O(3) bond length. In the second Co site, Co(2) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms to form edge-sharing CoO6 octahedra. The Co(2)-O(1) bond length is 1.96 Å. The Co(2)-O(3) bond length is 2.08 Å. There is one shorter (1.94 Å) and one longer (2.09 Å) Co(2)-O(2) bond length. There is one shorter (2.01 Å) and one longer (2.08 Å) Co(2)-O(4) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Na(1), one Co(2), and two equivalent Co(1) atoms. In the second O site, O(2) is bonded to two equivalent Na(1), one Co(1), and two equivalent Co(2) atoms to form a mixture of distorted corner and edge-sharing ONa2Co3 square pyramids. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Co(2), and two equivalent Co(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Na(1), one Co(1), and two equivalent Co(2) atoms to form a mixture of distorted corner and edge-sharing ONa2Co3 trigonal bipyramids.