Na3Hg2 crystallizes in the tetragonal P4_2/mnm space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent Na(3) and six equivalent Hg(1) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent Na(3) and six equivalent Hg(1) atoms. In the third Na site, Na(3) is bonded in a 10-coordinate geometry to two equivalent Na(1), two equivalent Na(2), two equivalent Na(3), and four equivalent Hg(1) atoms. In the fourth Na site, Na(3) is bonded in a 10-coordinate geometry to two equivalent Na(1), two equivalent Na(2), two equivalent Na(3), and four equivalent Hg(1) atoms. Hg(1) is bonded in a 6-coordinate geometry to two equivalent Na(3), three equivalent Na(1), and three equivalent Na(2) atoms.
Na3Hg2 crystallizes in the tetragonal P4_2/mnm space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent Na(3) and six equivalent Hg(1) atoms. Both Na(1)-Na(3) bond lengths are 3.34 Å. There are two shorter (3.14 Å) and four longer (3.15 Å) Na(1)-Hg(1) bond lengths. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent Na(3) and six equivalent Hg(1) atoms. Both Na(2)-Na(3) bond lengths are 3.12 Å. There are two shorter (3.04 Å) and four longer (3.13 Å) Na(2)-Hg(1) bond lengths. In the third Na site, Na(3) is bonded in a 10-coordinate geometry to two equivalent Na(1), two equivalent Na(2), two equivalent Na(3), and four equivalent Hg(1) atoms. Both Na(3)-Na(3) bond lengths are 3.59 Å. All Na(3)-Hg(1) bond lengths are 3.61 Å. In the fourth Na site, Na(3) is bonded in a 10-coordinate geometry to two equivalent Na(1), two equivalent Na(2), two equivalent Na(3), and four equivalent Hg(1) atoms. Both Na(3)-Na(1) bond lengths are 3.34 Å. Both Na(3)-Na(2) bond lengths are 3.12 Å. All Na(3)-Hg(1) bond lengths are 3.61 Å. Hg(1) is bonded in a 6-coordinate geometry to two equivalent Na(3), three equivalent Na(1), and three equivalent Na(2) atoms.