Li2Nb(PO3)5 crystallizes in the monoclinic P2_1/m space group. Li(1) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(9), and two equivalent O(2) atoms. Nb(1) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(8) atoms to form NbO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with four equivalent P(1)O4 tetrahedra. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Nb(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-56°. In the second P site, P(2) is bonded to one O(2), one O(4), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. In the third P site, P(3) is bonded to one O(3), one O(9), and two equivalent O(7) atoms to form corner-sharing PO4 tetrahedra. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent P(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Li(1) and one P(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Li(1) and one P(3) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Nb(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Nb(1) and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one P(2) and one P(3) atom. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Nb(1) and one P(2) atom. In the ninth O site, O(9) is bonded in a trigonal planar geometry to two equivalent Li(1) and one P(3) atom.
Li2Nb(PO3)5 crystallizes in the monoclinic P2_1/m space group. Li(1) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(9), and two equivalent O(2) atoms. The Li(1)-O(3) bond length is 2.26 Å. The Li(1)-O(9) bond length is 2.19 Å. There is one shorter (2.04 Å) and one longer (2.51 Å) Li(1)-O(2) bond length. Nb(1) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(8) atoms to form NbO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with four equivalent P(1)O4 tetrahedra. Both Nb(1)-O(5) bond lengths are 2.22 Å. Both Nb(1)-O(6) bond lengths are 2.14 Å. Both Nb(1)-O(8) bond lengths are 2.13 Å. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Nb(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-56°. The P(1)-O(1) bond length is 1.59 Å. The P(1)-O(4) bond length is 1.60 Å. The P(1)-O(5) bond length is 1.51 Å. The P(1)-O(6) bond length is 1.51 Å. In the second P site, P(2) is bonded to one O(2), one O(4), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. The P(2)-O(2) bond length is 1.49 Å. The P(2)-O(4) bond length is 1.62 Å. The P(2)-O(7) bond length is 1.60 Å. The P(2)-O(8) bond length is 1.52 Å. In the third P site, P(3) is bonded to one O(3), one O(9), and two equivalent O(7) atoms to form corner-sharing PO4 tetrahedra. The P(3)-O(3) bond length is 1.49 Å. The P(3)-O(9) bond length is 1.50 Å. Both P(3)-O(7) bond lengths are 1.63 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent P(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Li(1) and one P(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Li(1) and one P(3) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Nb(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Nb(1) and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one P(2) and one P(3) atom. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Nb(1) and one P(2) atom. In the ninth O site, O(9) is bonded in a trigonal planar geometry to two equivalent Li(1) and one P(3) atom.