HNbO3 crystallizes in the triclinic P1 space group. The structure consists of one water atom inside a Nb4H4O11 framework. In the Nb4H4O11 framework, there are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted bent 150 degrees geometry to one H(1), one O(1), one O(2), and one O(6) atom. In the second Nb site, Nb(2) is bonded in a 5-coordinate geometry to one H(3), one O(11), one O(12), one O(6), one O(8), and one O(9) atom. In the third Nb site, Nb(3) is bonded in a 1-coordinate geometry to one H(1), one O(3), one O(4), and one O(8) atom. In the fourth Nb site, Nb(4) is bonded in a 8-coordinate geometry to one H(4), one O(10), one O(11), one O(12), one O(3), one O(4), one O(6), and one O(9) atom. There are four inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one Nb(1), one Nb(3), and one O(2) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one O(12) and one O(3) atom. In the third H site, H(3) is bonded in a distorted single-bond geometry to one Nb(2) and one O(7) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one Nb(4) and one O(11) atom. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Nb(1) and one O(9) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Nb(1) and one H(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Nb(3), one Nb(4), one H(2), and one O(12) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Nb(3), one Nb(4), one O(11), and one O(6) atom. In the fifth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Nb(1), one Nb(2), one Nb(4), and one O(4) atom. In the sixth O site, O(7) is bonded in a single-bond geometry to one H(3) atom. In the seventh O site, O(8) is bonded in a bent 120 degrees geometry to one Nb(2) and one Nb(3) atom. In the eighth O site, O(9) is bonded in a distorted T-shaped geometry to one Nb(2), one Nb(4), and one O(1) atom. In the ninth O site, O(10) is bonded in a 5-coordinate geometry to one Nb(4) atom. In the tenth O site, O(11) is bonded in a distorted single-bond geometry to one Nb(2), one Nb(4), one H(4), and one O(4) atom. In the eleventh O site, O(12) is bonded in a 4-coordinate geometry to one Nb(2), one Nb(4), one H(2), and one O(3) atom.
HNbO3 crystallizes in the triclinic P1 space group. The structure consists of one water atom inside a Nb4H4O11 framework. In the Nb4H4O11 framework, there are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted bent 150 degrees geometry to one H(1), one O(1), one O(2), and one O(6) atom. The Nb(1)-H(1) bond length is 1.73 Å. The Nb(1)-O(1) bond length is 1.45 Å. The Nb(1)-O(2) bond length is 1.22 Å. The Nb(1)-O(6) bond length is 2.47 Å. In the second Nb site, Nb(2) is bonded in a 5-coordinate geometry to one H(3), one O(11), one O(12), one O(6), one O(8), and one O(9) atom. The Nb(2)-H(3) bond length is 2.08 Å. The Nb(2)-O(11) bond length is 2.34 Å. The Nb(2)-O(12) bond length is 2.39 Å. The Nb(2)-O(6) bond length is 3.00 Å. The Nb(2)-O(8) bond length is 2.26 Å. The Nb(2)-O(9) bond length is 2.31 Å. In the third Nb site, Nb(3) is bonded in a 1-coordinate geometry to one H(1), one O(3), one O(4), and one O(8) atom. The Nb(3)-H(1) bond length is 2.36 Å. The Nb(3)-O(3) bond length is 1.66 Å. The Nb(3)-O(4) bond length is 2.34 Å. The Nb(3)-O(8) bond length is 2.43 Å. In the fourth Nb site, Nb(4) is bonded in a 8-coordinate geometry to one H(4), one O(10), one O(11), one O(12), one O(3), one O(4), one O(6), and one O(9) atom. The Nb(4)-H(4) bond length is 2.35 Å. The Nb(4)-O(10) bond length is 2.70 Å. The Nb(4)-O(11) bond length is 2.32 Å. The Nb(4)-O(12) bond length is 2.31 Å. The Nb(4)-O(3) bond length is 2.13 Å. The Nb(4)-O(4) bond length is 2.14 Å. The Nb(4)-O(6) bond length is 2.68 Å. The Nb(4)-O(9) bond length is 2.60 Å. There are four inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one Nb(1), one Nb(3), and one O(2) atom. The H(1)-O(2) bond length is 1.50 Å. In the second H site, H(2) is bonded in a distorted single-bond geometry to one O(12) and one O(3) atom. The H(2)-O(12) bond length is 1.72 Å. The H(2)-O(3) bond length is 1.35 Å. In the third H site, H(3) is bonded in a distorted single-bond geometry to one Nb(2) and one O(7) atom. The H(3)-O(7) bond length is 1.20 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one Nb(4) and one O(11) atom. The H(4)-O(11) bond length is 1.53 Å. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Nb(1) and one O(9) atom. The O(1)-O(9) bond length is 1.79 Å. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Nb(1) and one H(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Nb(3), one Nb(4), one H(2), and one O(12) atom. The O(3)-O(12) bond length is 1.63 Å. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Nb(3), one Nb(4), one O(11), and one O(6) atom. The O(4)-O(11) bond length is 1.78 Å. The O(4)-O(6) bond length is 1.77 Å. In the fifth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Nb(1), one Nb(2), one Nb(4), and one O(4) atom. In the sixth O site, O(7) is bonded in a single-bond geometry to one H(3) atom. In the seventh O site, O(8) is bonded in a bent 120 degrees geometry to one Nb(2) and one Nb(3) atom. In the eighth O site, O(9) is bonded in a distorted T-shaped geometry to one Nb(2), one Nb(4), and one O(1) atom. In the ninth O site, O(10) is bonded in a 5-coordinate geometry to one Nb(4) atom. In the tenth O site, O(11) is bonded in a distorted single-bond geometry to one Nb(2), one Nb(4), one H(4), and one O(4) atom. In the eleventh O site, O(12) is bonded in a 4-coordinate geometry to one Nb(2), one Nb(4), one H(2), and one O(3) atom.