Nb2P4H3O16 crystallizes in the triclinic P1 space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(12), one O(14), one O(15), one O(2), one O(3), and one O(5) atom to form NbO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with two equivalent P(3)O4 tetrahedra. In the second Nb site, Nb(2) is bonded to one O(1), one O(11), one O(16), one O(6), one O(8), and one O(9) atom to form NbO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent P(4)O4 tetrahedra. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(16), one O(2), one O(4), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra and corners with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 17-45°. In the second P site, P(2) is bonded to one O(11), one O(12), one O(3), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(2)O6 octahedra and corners with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-42°. In the third P site, P(3) is bonded to one O(10), one O(14), one O(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(2)O6 octahedra and corners with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-42°. In the fourth P site, P(4) is bonded to one O(1), one O(13), one O(15), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra and corners with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 17-44°. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(4) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(13) atom. In the third H site, H(3) is bonded in a linear geometry to one O(10) and one O(7) atom. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Nb(2) and one P(4) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a water-like geometry to one P(1) and one H(1) atom. In the fifth O site, O(5) is bonded in a linear geometry to one Nb(1) and one P(3) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(3) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one P(2) and one H(3) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Nb(2) and one P(1) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one Nb(2) and one P(4) atom. In the tenth O site, O(10) is bonded in a bent 120 degrees geometry to one P(3) and one H(3) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(2) atom. In the twelfth O site, O(12) is bonded in a linear geometry to one Nb(1) and one P(2) atom. In the thirteenth O site, O(13) is bonded in a water-like geometry to one P(4) and one H(2) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 150 degrees geometry to one Nb(1) and one P(3) atom. In the fifteenth O site, O(15) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(4) atom. In the sixteenth O site, O(16) is bonded in a linear geometry to one Nb(2) and one P(1) atom.
Nb2P4H3O16 crystallizes in the triclinic P1 space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(12), one O(14), one O(15), one O(2), one O(3), and one O(5) atom to form NbO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with two equivalent P(3)O4 tetrahedra. The Nb(1)-O(12) bond length is 1.98 Å. The Nb(1)-O(14) bond length is 2.04 Å. The Nb(1)-O(15) bond length is 2.02 Å. The Nb(1)-O(2) bond length is 2.02 Å. The Nb(1)-O(3) bond length is 1.98 Å. The Nb(1)-O(5) bond length is 2.04 Å. In the second Nb site, Nb(2) is bonded to one O(1), one O(11), one O(16), one O(6), one O(8), and one O(9) atom to form NbO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent P(4)O4 tetrahedra. The Nb(2)-O(1) bond length is 1.98 Å. The Nb(2)-O(11) bond length is 2.08 Å. The Nb(2)-O(16) bond length is 1.98 Å. The Nb(2)-O(6) bond length is 2.11 Å. The Nb(2)-O(8) bond length is 2.13 Å. The Nb(2)-O(9) bond length is 2.13 Å. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(16), one O(2), one O(4), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra and corners with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 17-45°. The P(1)-O(16) bond length is 1.54 Å. The P(1)-O(2) bond length is 1.53 Å. The P(1)-O(4) bond length is 1.59 Å. The P(1)-O(8) bond length is 1.52 Å. In the second P site, P(2) is bonded to one O(11), one O(12), one O(3), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(2)O6 octahedra and corners with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-42°. The P(2)-O(11) bond length is 1.56 Å. The P(2)-O(12) bond length is 1.59 Å. The P(2)-O(3) bond length is 1.59 Å. The P(2)-O(7) bond length is 1.49 Å. In the third P site, P(3) is bonded to one O(10), one O(14), one O(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(2)O6 octahedra and corners with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-42°. The P(3)-O(10) bond length is 1.55 Å. The P(3)-O(14) bond length is 1.56 Å. The P(3)-O(5) bond length is 1.56 Å. The P(3)-O(6) bond length is 1.54 Å. In the fourth P site, P(4) is bonded to one O(1), one O(13), one O(15), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra and corners with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 17-44°. The P(4)-O(1) bond length is 1.54 Å. The P(4)-O(13) bond length is 1.59 Å. The P(4)-O(15) bond length is 1.53 Å. The P(4)-O(9) bond length is 1.52 Å. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(4) atom. The H(1)-O(4) bond length is 0.96 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(13) atom. The H(2)-O(13) bond length is 0.96 Å. In the third H site, H(3) is bonded in a linear geometry to one O(10) and one O(7) atom. The H(3)-O(10) bond length is 1.04 Å. The H(3)-O(7) bond length is 1.56 Å. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Nb(2) and one P(4) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a water-like geometry to one P(1) and one H(1) atom. In the fifth O site, O(5) is bonded in a linear geometry to one Nb(1) and one P(3) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(3) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one P(2) and one H(3) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Nb(2) and one P(1) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one Nb(2) and one P(4) atom. In the tenth O site, O(10) is bonded in a bent 120 degrees geometry to one P(3) and one H(3) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(2) atom. In the twelfth O site, O(12) is bonded in a linear geometry to one Nb(1) and one P(2) atom. In the thirteenth O site, O(13) is bonded in a water-like geometry to one P(4) and one H(2) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 150 degrees geometry to one Nb(1) and one P(3) atom. In the fifteenth O site, O(15) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(4) atom. In the sixteenth O site, O(16) is bonded in a linear geometry to one Nb(2) and one P(1) atom.