KNaSnSi5O16 crystallizes in the monoclinic C2/m space group. K(1) is bonded in a 7-coordinate geometry to one O(9), two equivalent O(1), two equivalent O(7), and two equivalent O(8) atoms. Na(1) is bonded to two equivalent O(2), two equivalent O(6), and two equivalent O(9) atoms to form distorted NaO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Na(1)O6 octahedra, and edges with two equivalent Sn(1)O6 octahedra. Sn(1) is bonded to two equivalent O(2), two equivalent O(6), and two equivalent O(7) atoms to form SnO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra, and edges with two equivalent Na(1)O6 octahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra,  a cornercorner with one Sn(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-52°. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra, corners with two equivalent Sn(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-63°. In the third Si site, Si(3) is bonded to two equivalent O(4) and two equivalent O(5) atoms to form corner-sharing SiO4 tetrahedra. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one K(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(1), one Sn(1), and one Si(2) atom. In the third O site, O(3) is bonded in a linear geometry to two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(1), one Sn(1), and one Si(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one K(1), one Sn(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a distorted L-shaped geometry to one K(1) and one O(8) atom. In the ninth O site, O(9) is bonded in a trigonal non-coplanar geometry to one K(1) and two equivalent Na(1) atoms.
KNaSnSi5O16 crystallizes in the monoclinic C2/m space group. K(1) is bonded in a 7-coordinate geometry to one O(9), two equivalent O(1), two equivalent O(7), and two equivalent O(8) atoms. The K(1)-O(9) bond length is 2.90 Å. Both K(1)-O(1) bond lengths are 3.21 Å. Both K(1)-O(7) bond lengths are 2.93 Å. Both K(1)-O(8) bond lengths are 2.99 Å. Na(1) is bonded to two equivalent O(2), two equivalent O(6), and two equivalent O(9) atoms to form distorted NaO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Na(1)O6 octahedra, and edges with two equivalent Sn(1)O6 octahedra. Both Na(1)-O(2) bond lengths are 2.32 Å. Both Na(1)-O(6) bond lengths are 2.35 Å. Both Na(1)-O(9) bond lengths are 2.30 Å. Sn(1) is bonded to two equivalent O(2), two equivalent O(6), and two equivalent O(7) atoms to form SnO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra, and edges with two equivalent Na(1)O6 octahedra. Both Sn(1)-O(2) bond lengths are 2.08 Å. Both Sn(1)-O(6) bond lengths are 2.08 Å. Both Sn(1)-O(7) bond lengths are 2.07 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra,  a cornercorner with one Sn(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-52°. The Si(1)-O(1) bond length is 1.65 Å. The Si(1)-O(3) bond length is 1.62 Å. The Si(1)-O(4) bond length is 1.63 Å. The Si(1)-O(6) bond length is 1.63 Å. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra, corners with two equivalent Sn(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-63°. The Si(2)-O(1) bond length is 1.66 Å. The Si(2)-O(2) bond length is 1.63 Å. The Si(2)-O(5) bond length is 1.64 Å. The Si(2)-O(7) bond length is 1.63 Å. In the third Si site, Si(3) is bonded to two equivalent O(4) and two equivalent O(5) atoms to form corner-sharing SiO4 tetrahedra. Both Si(3)-O(4) bond lengths are 1.63 Å. Both Si(3)-O(5) bond lengths are 1.62 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one K(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(1), one Sn(1), and one Si(2) atom. In the third O site, O(3) is bonded in a linear geometry to two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(1), one Sn(1), and one Si(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one K(1), one Sn(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a distorted L-shaped geometry to one K(1) and one O(8) atom. The O(8)-O(8) bond length is 1.24 Å. In the ninth O site, O(9) is bonded in a trigonal non-coplanar geometry to one K(1) and two equivalent Na(1) atoms.