Na4CO4 crystallizes in the monoclinic Cm 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) and four equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(1), and two equivalent O(3) atoms. In the third Na site, Na(3) is bonded in a 3-coordinate geometry to one O(3) and two equivalent O(2) atoms. C(1) is bonded in a tetrahedral geometry to one O(1), one O(3), and two equivalent O(2) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Na(1), four equivalent Na(2), and one C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Na(2), one Na(3), two equivalent Na(1), and one C(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Na(3), four equivalent Na(2), and one C(1) atom.
Na4CO4 crystallizes in the monoclinic Cm 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) and four equivalent O(2) atoms. The Na(1)-O(1) bond length is 2.22 Å. There are two shorter (2.32 Å) and two longer (2.59 Å) Na(1)-O(2) bond lengths. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(1), and two equivalent O(3) atoms. The Na(2)-O(2) bond length is 2.23 Å. There is one shorter (2.32 Å) and one longer (2.54 Å) Na(2)-O(1) bond length. There is one shorter (2.39 Å) and one longer (2.45 Å) Na(2)-O(3) bond length. In the third Na site, Na(3) is bonded in a 3-coordinate geometry to one O(3) and two equivalent O(2) atoms. The Na(3)-O(3) bond length is 2.44 Å. Both Na(3)-O(2) bond lengths are 2.22 Å. C(1) is bonded in a tetrahedral geometry to one O(1), one O(3), and two equivalent O(2) atoms. The C(1)-O(1) bond length is 1.47 Å. The C(1)-O(3) bond length is 1.47 Å. Both C(1)-O(2) bond lengths are 1.44 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Na(1), four equivalent Na(2), and one C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Na(2), one Na(3), two equivalent Na(1), and one C(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Na(3), four equivalent Na(2), and one C(1) atom.