NbV3O8 is Hydrophilite-derived structured and crystallizes in the monoclinic Cc space group. Nb(1) is bonded to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form distorted NbO6 octahedra that share corners with two equivalent V(1)O6 octahedra, corners with two equivalent V(2)O6 octahedra, corners with two equivalent V(3)O6 octahedra,  an edgeedge with one V(1)O6 octahedra,  an edgeedge with one V(2)O6 octahedra, and  an edgeedge with one V(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-55°. There are three inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(8) atom to form VO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra, edges with two equivalent V(2)O6 octahedra, and edges with two equivalent V(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-49°. In the second V site, V(2) is bonded to one O(2), one O(3), one O(4), one O(5), one O(7), and one O(8) atom to form VO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra, edges with two equivalent V(1)O6 octahedra, and edges with two equivalent V(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-55°. In the third V site, V(3) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form VO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra, edges with two equivalent V(1)O6 octahedra, and edges with two equivalent V(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-52°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Nb(1), one V(1), and one V(3) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Nb(1), one V(1), and one V(2) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one V(1), one V(2), and one V(3) atom. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one V(1), one V(2), and one V(3) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Nb(1), one V(2), and one V(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Nb(1), one V(1), and one V(3) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Nb(1), one V(2), and one V(3) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Nb(1), one V(1), and one V(2) atom.
NbV3O8 is Hydrophilite-derived structured and crystallizes in the monoclinic Cc space group. Nb(1) is bonded to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form distorted NbO6 octahedra that share corners with two equivalent V(1)O6 octahedra, corners with two equivalent V(2)O6 octahedra, corners with two equivalent V(3)O6 octahedra,  an edgeedge with one V(1)O6 octahedra,  an edgeedge with one V(2)O6 octahedra, and  an edgeedge with one V(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-55°. The Nb(1)-O(1) bond length is 1.95 Å. The Nb(1)-O(2) bond length is 2.20 Å. The Nb(1)-O(5) bond length is 1.95 Å. The Nb(1)-O(6) bond length is 2.06 Å. The Nb(1)-O(7) bond length is 2.17 Å. The Nb(1)-O(8) bond length is 1.91 Å. There are three inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(8) atom to form VO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra, edges with two equivalent V(2)O6 octahedra, and edges with two equivalent V(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-49°. The V(1)-O(1) bond length is 2.06 Å. The V(1)-O(2) bond length is 1.82 Å. The V(1)-O(3) bond length is 1.97 Å. The V(1)-O(4) bond length is 1.94 Å. The V(1)-O(6) bond length is 2.00 Å. The V(1)-O(8) bond length is 2.09 Å. In the second V site, V(2) is bonded to one O(2), one O(3), one O(4), one O(5), one O(7), and one O(8) atom to form VO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra, edges with two equivalent V(1)O6 octahedra, and edges with two equivalent V(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-55°. The V(2)-O(2) bond length is 2.08 Å. The V(2)-O(3) bond length is 1.98 Å. The V(2)-O(4) bond length is 1.98 Å. The V(2)-O(5) bond length is 2.09 Å. The V(2)-O(7) bond length is 2.09 Å. The V(2)-O(8) bond length is 2.08 Å. In the third V site, V(3) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form VO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra, edges with two equivalent V(1)O6 octahedra, and edges with two equivalent V(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-52°. The V(3)-O(1) bond length is 2.07 Å. The V(3)-O(3) bond length is 1.97 Å. The V(3)-O(4) bond length is 1.95 Å. The V(3)-O(5) bond length is 2.06 Å. The V(3)-O(6) bond length is 2.00 Å. The V(3)-O(7) bond length is 1.84 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Nb(1), one V(1), and one V(3) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Nb(1), one V(1), and one V(2) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one V(1), one V(2), and one V(3) atom. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one V(1), one V(2), and one V(3) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Nb(1), one V(2), and one V(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Nb(1), one V(1), and one V(3) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Nb(1), one V(2), and one V(3) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Nb(1), one V(1), and one V(2) atom.