NbO2 crystallizes in the tetragonal I4_1/a space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form distorted corner-sharing NbO4 trigonal pyramids. In the second Nb site, Nb(2) is bonded to one O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted NbO5 trigonal bipyramids that share corners with five equivalent Nb(1)O4 trigonal pyramids and edges with two equivalent Nb(2)O5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Nb(1) atom. In the second O site, O(3) is bonded in a distorted trigonal planar geometry to one Nb(1) and two equivalent Nb(2) atoms. In the third O site, O(2) is bonded in a bent 120 degrees geometry to one Nb(1) and one Nb(2) atom. In the fourth O site, O(4) is bonded in a T-shaped geometry to one Nb(1) and two equivalent Nb(2) atoms.
NbO2 crystallizes in the tetragonal I4_1/a space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form distorted corner-sharing NbO4 trigonal pyramids. The Nb(1)-O(1) bond length is 1.74 Å. The Nb(1)-O(2) bond length is 2.02 Å. The Nb(1)-O(3) bond length is 2.23 Å. The Nb(1)-O(4) bond length is 2.10 Å. In the second Nb site, Nb(2) is bonded to one O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted NbO5 trigonal bipyramids that share corners with five equivalent Nb(1)O4 trigonal pyramids and edges with two equivalent Nb(2)O5 trigonal bipyramids. The Nb(2)-O(2) bond length is 1.85 Å. There is one shorter (2.00 Å) and one longer (2.09 Å) Nb(2)-O(3) bond length. There is one shorter (2.06 Å) and one longer (2.08 Å) Nb(2)-O(4) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Nb(1) atom. In the second O site, O(3) is bonded in a distorted trigonal planar geometry to one Nb(1) and two equivalent Nb(2) atoms. In the third O site, O(2) is bonded in a bent 120 degrees geometry to one Nb(1) and one Nb(2) atom. In the fourth O site, O(4) is bonded in a T-shaped geometry to one Nb(1) and two equivalent Nb(2) atoms.