Na4Si23 crystallizes in the cubic Pm-3n space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to eight equivalent Si(2) atoms. In the second Na site, Na(2) is bonded in a 20-coordinate geometry to eight equivalent Si(1) and twelve equivalent Si(2) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted pentagonal planar geometry to one Na(2), one Si(1), and three equivalent Si(2) atoms. In the second Si site, Si(3) is bonded in a tetrahedral geometry to four equivalent Si(2) atoms. In the third Si site, Si(2) is bonded in a 7-coordinate geometry to one Na(2), two equivalent Na(1), one Si(2), one Si(3), and two equivalent Si(1) atoms.
Na4Si23 crystallizes in the cubic Pm-3n space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to eight equivalent Si(2) atoms. All Na(1)-Si(2) bond lengths are 3.43 Å. In the second Na site, Na(2) is bonded in a 20-coordinate geometry to eight equivalent Si(1) and twelve equivalent Si(2) atoms. All Na(2)-Si(1) bond lengths are 3.25 Å. All Na(2)-Si(2) bond lengths are 3.35 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted pentagonal planar geometry to one Na(2), one Si(1), and three equivalent Si(2) atoms. The Si(1)-Si(1) bond length is 2.32 Å. All Si(1)-Si(2) bond lengths are 2.36 Å. In the second Si site, Si(3) is bonded in a tetrahedral geometry to four equivalent Si(2) atoms. All Si(3)-Si(2) bond lengths are 2.38 Å. In the third Si site, Si(2) is bonded in a 7-coordinate geometry to one Na(2), two equivalent Na(1), one Si(2), one Si(3), and two equivalent Si(1) atoms. The Si(2)-Si(2) bond length is 2.38 Å.