NiNb2O6 is Hydrophilite-derived structured and crystallizes in the monoclinic C2/m space group. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NbO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra, corners with six equivalent Ni(1)O6 octahedra, and edges with two equivalent Nb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-51°. In the second Nb site, Nb(2) is bonded to two equivalent O(3) and four equivalent O(5) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with six equivalent Nb(3)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-51°. In the third Nb site, Nb(3) is bonded to one O(1), one O(3), two equivalent O(4), and two equivalent O(5) atoms to form NbO6 octahedra that share corners with three equivalent Nb(2)O6 octahedra, corners with five equivalent Ni(1)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra, and  an edgeedge with one Nb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-58°. Ni(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with five equivalent Nb(3)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-58°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Nb(1), one Nb(3), and one Ni(1) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Nb(1) and two equivalent Ni(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Nb(1), one Nb(2), and one Nb(3) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Nb(3) and one Ni(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Nb(2), one Nb(3), and one Ni(1) atom.
NiNb2O6 is Hydrophilite-derived structured and crystallizes in the monoclinic C2/m space group. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NbO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra, corners with six equivalent Ni(1)O6 octahedra, and edges with two equivalent Nb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-51°. Both Nb(1)-O(1) bond lengths are 2.05 Å. Both Nb(1)-O(2) bond lengths are 1.95 Å. Both Nb(1)-O(3) bond lengths are 2.08 Å. In the second Nb site, Nb(2) is bonded to two equivalent O(3) and four equivalent O(5) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with six equivalent Nb(3)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-51°. Both Nb(2)-O(3) bond lengths are 2.07 Å. All Nb(2)-O(5) bond lengths are 2.00 Å. In the third Nb site, Nb(3) is bonded to one O(1), one O(3), two equivalent O(4), and two equivalent O(5) atoms to form NbO6 octahedra that share corners with three equivalent Nb(2)O6 octahedra, corners with five equivalent Ni(1)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra, and  an edgeedge with one Nb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-58°. The Nb(3)-O(1) bond length is 1.92 Å. The Nb(3)-O(3) bond length is 2.17 Å. There is one shorter (1.91 Å) and one longer (2.13 Å) Nb(3)-O(4) bond length. Both Nb(3)-O(5) bond lengths are 2.02 Å. Ni(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with five equivalent Nb(3)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-58°. The Ni(1)-O(1) bond length is 2.11 Å. The Ni(1)-O(4) bond length is 2.07 Å. Both Ni(1)-O(2) bond lengths are 2.05 Å. Both Ni(1)-O(5) bond lengths are 2.17 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Nb(1), one Nb(3), and one Ni(1) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Nb(1) and two equivalent Ni(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Nb(1), one Nb(2), and one Nb(3) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Nb(3) and one Ni(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Nb(2), one Nb(3), and one Ni(1) atom.