NaSi2O5 crystallizes in the tetragonal I-4 space group. Na(1) is bonded in a 5-coordinate geometry to one O(2), one O(4), and three equivalent O(3) 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 two equivalent O(5) atoms to form SiO5 trigonal bipyramids that share corners with two equivalent Si(2)O4 tetrahedra and corners with two equivalent Si(1)O5 trigonal bipyramids. In the second Si site, Si(2) is bonded to one O(2), one O(4), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Si(2)O4 tetrahedra and corners with two equivalent Si(1)O5 trigonal bipyramids. There are five inequivalent O sites. In the first O site, O(3) is bonded in a 4-coordinate geometry to three equivalent Na(1) and one Si(1) atom. In the second O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Na(1), one Si(1), and one Si(2) atom. In the third O site, O(5) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the fourth O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Si(2) atoms. In the fifth O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Na(1), one Si(1), and one Si(2) atom.
NaSi2O5 crystallizes in the tetragonal I-4 space group. Na(1) is bonded in a 5-coordinate geometry to one O(2), one O(4), and three equivalent O(3) atoms. The Na(1)-O(2) bond length is 2.65 Å. The Na(1)-O(4) bond length is 2.58 Å. There are a spread of Na(1)-O(3) bond distances ranging from 2.38-2.91 Å. 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 two equivalent O(5) atoms to form SiO5 trigonal bipyramids that share corners with two equivalent Si(2)O4 tetrahedra and corners with two equivalent Si(1)O5 trigonal bipyramids. The Si(1)-O(2) bond length is 1.67 Å. The Si(1)-O(3) bond length is 1.72 Å. The Si(1)-O(4) bond length is 1.68 Å. There is one shorter (1.68 Å) and one longer (1.86 Å) Si(1)-O(5) bond length. In the second Si site, Si(2) is bonded to one O(2), one O(4), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Si(2)O4 tetrahedra and corners with two equivalent Si(1)O5 trigonal bipyramids. The Si(2)-O(2) bond length is 1.60 Å. The Si(2)-O(4) bond length is 1.61 Å. Both Si(2)-O(1) bond lengths are 1.64 Å. There are five inequivalent O sites. In the first O site, O(3) is bonded in a 4-coordinate geometry to three equivalent Na(1) and one Si(1) atom. In the second O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Na(1), one Si(1), and one Si(2) atom. In the third O site, O(5) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the fourth O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Si(2) atoms. In the fifth O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Na(1), one Si(1), and one Si(2) atom.