Na4CO4 crystallizes in the trigonal R3m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to six equivalent O(2) atoms. C(1) is bonded in a tetrahedral geometry to one O(1) and three equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to three equivalent Na(1) and one C(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one C(1) atom.
Na4CO4 crystallizes in the trigonal R3m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(2) atoms. The Na(1)-O(1) bond length is 2.16 Å. Both Na(1)-O(2) bond lengths are 2.22 Å. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to six equivalent O(2) atoms. There are three shorter (2.45 Å) and three longer (2.93 Å) Na(2)-O(2) bond lengths. C(1) is bonded in a tetrahedral geometry to one O(1) and three equivalent O(2) atoms. The C(1)-O(1) bond length is 1.37 Å. All C(1)-O(2) bond lengths are 1.45 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to three equivalent Na(1) and one C(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one C(1) atom.