(Nb(SiO3)4)2O2 crystallizes in the monoclinic P2_1/m space group. The structure consists of two water atoms inside a Nb(SiO3)4 framework. In the Nb(SiO3)4 framework, Nb(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra and corners with four equivalent Si(3)O4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(5), one O(6), and two equivalent O(7) atoms to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(2), one O(6), and two equivalent O(8) atoms to form SiO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 18°. In the third Si site, Si(3) is bonded to one O(1), one O(4), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Nb(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-30°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Nb(1) and one Si(3) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one Si(2) atom. In the third O site, O(3) is bonded in a single-bond geometry to one Nb(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Nb(1) and one Si(3) atom. In the fifth O site, O(5) is bonded in a single-bond geometry to one Si(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom.
(Nb(SiO3)4)2O2 crystallizes in the monoclinic P2_1/m space group. The structure consists of two water atoms inside a Nb(SiO3)4 framework. In the Nb(SiO3)4 framework, Nb(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra and corners with four equivalent Si(3)O4 tetrahedra. The Nb(1)-O(2) bond length is 1.92 Å. The Nb(1)-O(3) bond length is 2.10 Å. Both Nb(1)-O(1) bond lengths are 2.05 Å. Both Nb(1)-O(4) bond lengths are 1.92 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(5), one O(6), and two equivalent O(7) atoms to form corner-sharing SiO4 tetrahedra. The Si(1)-O(5) bond length is 1.65 Å. The Si(1)-O(6) bond length is 1.63 Å. Both Si(1)-O(7) bond lengths are 1.62 Å. In the second Si site, Si(2) is bonded to one O(2), one O(6), and two equivalent O(8) atoms to form SiO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 18°. The Si(2)-O(2) bond length is 1.63 Å. The Si(2)-O(6) bond length is 1.63 Å. Both Si(2)-O(8) bond lengths are 1.62 Å. In the third Si site, Si(3) is bonded to one O(1), one O(4), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Nb(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-30°. The Si(3)-O(1) bond length is 1.64 Å. The Si(3)-O(4) bond length is 1.64 Å. The Si(3)-O(7) bond length is 1.62 Å. The Si(3)-O(8) bond length is 1.63 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Nb(1) and one Si(3) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one Si(2) atom. In the third O site, O(3) is bonded in a single-bond geometry to one Nb(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Nb(1) and one Si(3) atom. In the fifth O site, O(5) is bonded in a single-bond geometry to one Si(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom.