Na4Si3(SnO6)2 crystallizes in the trigonal R-3c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to six equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(2) atoms. Sn(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form SnO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. Si(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with four equivalent Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-40°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(2), one Sn(1), and one Si(1) atom. In the second O site, O(2) is bonded to one Na(1), two equivalent Na(2), one Sn(1), and one Si(1) atom to form a mixture of distorted corner, edge, and face-sharing ONa3SiSn trigonal bipyramids.
Na4Si3(SnO6)2 crystallizes in the trigonal R-3c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to six equivalent O(2) atoms. All Na(1)-O(2) bond lengths are 2.42 Å. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(2) atoms. Both Na(2)-O(1) bond lengths are 2.55 Å. There are two shorter (2.49 Å) and two longer (2.50 Å) Na(2)-O(2) bond lengths. Sn(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form SnO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. All Sn(1)-O(1) bond lengths are 2.01 Å. All Sn(1)-O(2) bond lengths are 2.07 Å. Si(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with four equivalent Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-40°. Both Si(1)-O(1) bond lengths are 1.62 Å. Both Si(1)-O(2) bond lengths are 1.63 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(2), one Sn(1), and one Si(1) atom. In the second O site, O(2) is bonded to one Na(1), two equivalent Na(2), one Sn(1), and one Si(1) atom to form a mixture of distorted corner, edge, and face-sharing ONa3SiSn trigonal bipyramids.