NaYSi2O6 crystallizes in the monoclinic P2_1/c space group. Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(3), and two equivalent O(4) atoms. Y(1) is bonded to one O(2), one O(3), one O(4), two equivalent O(5), and two equivalent O(6) atoms to form YO7 pentagonal bipyramids that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Y(1)O7 pentagonal bipyramids,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Y(1)O7 pentagonal bipyramids, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. 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 Y(1)O7 pentagonal bipyramids, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Y(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Y(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Na(1), one Y(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Y(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Y(1), and one Si(1) atom.
NaYSi2O6 crystallizes in the monoclinic P2_1/c space group. Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(3), and two equivalent O(4) atoms. The Na(1)-O(1) bond length is 2.35 Å. The Na(1)-O(6) bond length is 2.92 Å. There is one shorter (2.43 Å) and one longer (2.77 Å) Na(1)-O(3) bond length. There is one shorter (2.38 Å) and one longer (3.03 Å) Na(1)-O(4) bond length. Y(1) is bonded to one O(2), one O(3), one O(4), two equivalent O(5), and two equivalent O(6) atoms to form YO7 pentagonal bipyramids that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Y(1)O7 pentagonal bipyramids,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. The Y(1)-O(2) bond length is 2.47 Å. The Y(1)-O(3) bond length is 2.31 Å. The Y(1)-O(4) bond length is 2.27 Å. There is one shorter (2.23 Å) and one longer (2.52 Å) Y(1)-O(5) bond length. There is one shorter (2.25 Å) and one longer (2.54 Å) Y(1)-O(6) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Y(1)O7 pentagonal bipyramids, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. The Si(1)-O(1) bond length is 1.67 Å. The Si(1)-O(2) bond length is 1.67 Å. The Si(1)-O(3) bond length is 1.61 Å. The Si(1)-O(6) bond length is 1.62 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 Y(1)O7 pentagonal bipyramids, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. The Si(2)-O(1) bond length is 1.66 Å. The Si(2)-O(2) bond length is 1.67 Å. The Si(2)-O(4) bond length is 1.60 Å. The Si(2)-O(5) bond length is 1.62 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Y(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Y(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Na(1), one Y(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Y(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Y(1), and one Si(1) atom.