Na5Zr2Si6O20Cl crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(5), one O(6), and one Cl(1) atom. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to four equivalent O(4) and two equivalent Cl(1) atoms. Zr(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form ZrO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with four equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(3) and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with two equivalent Zr(1)O6 octahedra and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Zr(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 40-43°. There are six inequivalent O sites. In the first O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent Si(2) atoms. In the second O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Zr(1), and one Si(1) atom. In the third O site, O(4) is bonded in a 3-coordinate geometry to one Na(2), one Zr(1), and one Si(2) atom. In the fourth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Si(1), and one Si(2) atom. In the fifth O site, O(6) is bonded in a bent 120 degrees geometry to two equivalent Na(1) atoms. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Zr(1), and one Si(2) atom. Cl(1) is bonded to two equivalent Na(2) and four equivalent Na(1) atoms to form distorted corner-sharing ClNa6 octahedra. The corner-sharing octahedra are not tilted.
Na5Zr2Si6O20Cl crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(5), one O(6), and one Cl(1) atom. The Na(1)-O(1) bond length is 2.50 Å. The Na(1)-O(3) bond length is 2.41 Å. The Na(1)-O(5) bond length is 2.52 Å. The Na(1)-O(6) bond length is 2.41 Å. The Na(1)-Cl(1) bond length is 2.99 Å. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to four equivalent O(4) and two equivalent Cl(1) atoms. All Na(2)-O(4) bond lengths are 2.32 Å. Both Na(2)-Cl(1) bond lengths are 3.33 Å. Zr(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form ZrO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with four equivalent Si(2)O4 tetrahedra. Both Zr(1)-O(1) bond lengths are 2.12 Å. Both Zr(1)-O(3) bond lengths are 2.13 Å. Both Zr(1)-O(4) bond lengths are 2.11 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(3) and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with two equivalent Zr(1)O6 octahedra and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. Both Si(1)-O(3) bond lengths are 1.63 Å. Both Si(1)-O(5) bond lengths are 1.65 Å. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Zr(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 40-43°. The Si(2)-O(1) bond length is 1.62 Å. The Si(2)-O(2) bond length is 1.65 Å. The Si(2)-O(4) bond length is 1.62 Å. The Si(2)-O(5) bond length is 1.66 Å. There are six inequivalent O sites. In the first O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent Si(2) atoms. In the second O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Zr(1), and one Si(1) atom. In the third O site, O(4) is bonded in a 3-coordinate geometry to one Na(2), one Zr(1), and one Si(2) atom. In the fourth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Si(1), and one Si(2) atom. In the fifth O site, O(6) is bonded in a bent 120 degrees geometry to two equivalent Na(1) atoms. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Zr(1), and one Si(2) atom. Cl(1) is bonded to two equivalent Na(2) and four equivalent Na(1) atoms to form distorted corner-sharing ClNa6 octahedra. The corner-sharing octahedra are not tilted.