Na2Ti2O5 is Chalcostibite-like structured and crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(1) atoms to form distorted NaO5 square pyramids that share corners with two equivalent Ti(1)O4 tetrahedra, corners with three equivalent Ti(2)O4 tetrahedra, corners with two equivalent Na(2)O4 trigonal pyramids,  an edgeedge with one Na(1)O5 square pyramid,  an edgeedge with one Ti(2)O4 tetrahedra, and  an edgeedge with one Na(2)O4 trigonal pyramid. In the second Na site, Na(2) is bonded to one O(1), one O(4), and two equivalent O(2) atoms to form NaO4 trigonal pyramids that share corners with two equivalent Na(1)O5 square pyramids,  a cornercorner with one Ti(2)O4 tetrahedra, corners with four equivalent Ti(1)O4 tetrahedra,  an edgeedge with one Na(1)O5 square pyramid, and  an edgeedge with one Na(2)O4 trigonal pyramid. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(5), and two equivalent O(4) atoms to form TiO4 tetrahedra that share corners with two equivalent Na(1)O5 square pyramids,  a cornercorner with one Ti(2)O4 tetrahedra, corners with two equivalent Ti(1)O4 tetrahedra, and corners with four equivalent Na(2)O4 trigonal pyramids. In the second Ti site, Ti(2) is bonded to one O(1), one O(5), and two equivalent O(3) atoms to form TiO4 tetrahedra that share corners with three equivalent Na(1)O5 square pyramids,  a cornercorner with one Ti(1)O4 tetrahedra, corners with two equivalent Ti(2)O4 tetrahedra,  a cornercorner with one Na(2)O4 trigonal pyramid, and  an edgeedge with one Na(1)O5 square pyramid. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one Ti(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(2), and one Ti(1) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Na(1) and two equivalent Ti(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Na(2) and two equivalent Ti(1) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Na(1), one Ti(1), and one Ti(2) atom.
Na2Ti2O5 is Chalcostibite-like structured and crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(1) atoms to form distorted NaO5 square pyramids that share corners with two equivalent Ti(1)O4 tetrahedra, corners with three equivalent Ti(2)O4 tetrahedra, corners with two equivalent Na(2)O4 trigonal pyramids,  an edgeedge with one Na(1)O5 square pyramid,  an edgeedge with one Ti(2)O4 tetrahedra, and  an edgeedge with one Na(2)O4 trigonal pyramid. The Na(1)-O(2) bond length is 2.53 Å. The Na(1)-O(3) bond length is 2.34 Å. The Na(1)-O(5) bond length is 2.37 Å. There is one shorter (2.41 Å) and one longer (2.77 Å) Na(1)-O(1) bond length. In the second Na site, Na(2) is bonded to one O(1), one O(4), and two equivalent O(2) atoms to form NaO4 trigonal pyramids that share corners with two equivalent Na(1)O5 square pyramids,  a cornercorner with one Ti(2)O4 tetrahedra, corners with four equivalent Ti(1)O4 tetrahedra,  an edgeedge with one Na(1)O5 square pyramid, and  an edgeedge with one Na(2)O4 trigonal pyramid. The Na(2)-O(1) bond length is 2.39 Å. The Na(2)-O(4) bond length is 2.43 Å. There is one shorter (2.43 Å) and one longer (2.47 Å) Na(2)-O(2) bond length. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(5), and two equivalent O(4) atoms to form TiO4 tetrahedra that share corners with two equivalent Na(1)O5 square pyramids,  a cornercorner with one Ti(2)O4 tetrahedra, corners with two equivalent Ti(1)O4 tetrahedra, and corners with four equivalent Na(2)O4 trigonal pyramids. The Ti(1)-O(2) bond length is 1.76 Å. The Ti(1)-O(5) bond length is 1.86 Å. There is one shorter (1.86 Å) and one longer (1.87 Å) Ti(1)-O(4) bond length. In the second Ti site, Ti(2) is bonded to one O(1), one O(5), and two equivalent O(3) atoms to form TiO4 tetrahedra that share corners with three equivalent Na(1)O5 square pyramids,  a cornercorner with one Ti(1)O4 tetrahedra, corners with two equivalent Ti(2)O4 tetrahedra,  a cornercorner with one Na(2)O4 trigonal pyramid, and  an edgeedge with one Na(1)O5 square pyramid. The Ti(2)-O(1) bond length is 1.74 Å. The Ti(2)-O(5) bond length is 1.86 Å. There is one shorter (1.85 Å) and one longer (1.87 Å) Ti(2)-O(3) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one Ti(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(2), and one Ti(1) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Na(1) and two equivalent Ti(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Na(2) and two equivalent Ti(1) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Na(1), one Ti(1), and one Ti(2) atom.