Na2Si2O5 crystallizes in the orthorhombic Pca2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(4), one O(5), two equivalent O(1), and two equivalent O(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form corner-sharing SiO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one Si(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one Si(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Na(1), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Na(1), one Na(2), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Na(2), one Si(1), and one Si(2) atom.
Na2Si2O5 crystallizes in the orthorhombic Pca2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. The Na(1)-O(3) bond length is 2.90 Å. The Na(1)-O(4) bond length is 2.58 Å. There is one shorter (2.47 Å) and one longer (2.53 Å) Na(1)-O(1) bond length. There is one shorter (2.37 Å) and one longer (2.40 Å) Na(1)-O(2) bond length. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(4), one O(5), two equivalent O(1), and two equivalent O(2) atoms. The Na(2)-O(4) bond length is 2.86 Å. The Na(2)-O(5) bond length is 2.58 Å. There is one shorter (2.39 Å) and one longer (2.40 Å) Na(2)-O(1) bond length. There is one shorter (2.39 Å) and one longer (2.87 Å) Na(2)-O(2) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form corner-sharing SiO4 tetrahedra. The Si(1)-O(2) bond length is 1.59 Å. The Si(1)-O(3) bond length is 1.66 Å. The Si(1)-O(4) bond length is 1.67 Å. The Si(1)-O(5) bond length is 1.67 Å. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form corner-sharing SiO4 tetrahedra. The Si(2)-O(1) bond length is 1.59 Å. The Si(2)-O(3) bond length is 1.67 Å. The Si(2)-O(4) bond length is 1.68 Å. The Si(2)-O(5) bond length is 1.66 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one Si(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one Si(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Na(1), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Na(1), one Na(2), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Na(2), one Si(1), and one Si(2) atom.