Hf2ON2 crystallizes in the monoclinic C2/m space group. There are three inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one N(2), one N(3), two equivalent N(1), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra are not tilted. In the second Hf site, Hf(2) is bonded in a 7-coordinate geometry to two equivalent N(1), two equivalent N(3), and three equivalent O(1) atoms. In the third Hf site, Hf(3) is bonded in a 7-coordinate geometry to two equivalent N(3), three equivalent N(2), one O(1), and one O(2) atom. There are three inequivalent N sites. In the first N site, N(1) is bonded to two equivalent Hf(1) and two equivalent Hf(2) atoms to form distorted NHf4 tetrahedra that share corners with two equivalent O(2)Hf6 octahedra, corners with two equivalent N(1)Hf4 tetrahedra, corners with two equivalent N(2)Hf4 tetrahedra, corners with two equivalent N(3)Hf5 trigonal bipyramids,  an edgeedge with one O(2)Hf6 octahedra,  an edgeedge with one N(1)Hf4 tetrahedra, and edges with two equivalent N(3)Hf5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 11°. In the second N site, N(2) is bonded to one Hf(1) and three equivalent Hf(3) atoms to form NHf4 tetrahedra that share  a cornercorner with one O(2)Hf6 octahedra, corners with two equivalent N(1)Hf4 tetrahedra, corners with two equivalent N(2)Hf4 tetrahedra, corners with five equivalent N(3)Hf5 trigonal bipyramids, edges with two equivalent O(2)Hf6 octahedra, edges with two equivalent N(2)Hf4 tetrahedra, and  an edgeedge with one N(3)Hf5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 45°. In the third N site, N(3) is bonded to one Hf(1), two equivalent Hf(2), and two equivalent Hf(3) atoms to form distorted NHf5 trigonal bipyramids that share corners with two equivalent N(1)Hf4 tetrahedra, corners with five equivalent N(2)Hf4 tetrahedra, edges with two equivalent O(2)Hf6 octahedra,  an edgeedge with one N(2)Hf4 tetrahedra, edges with two equivalent N(1)Hf4 tetrahedra, and edges with two equivalent N(3)Hf5 trigonal bipyramids. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Hf(3) and three equivalent Hf(2) atoms. In the second O site, O(2) is bonded to two equivalent Hf(3) and four equivalent Hf(1) atoms to form OHf6 octahedra that share corners with two equivalent N(2)Hf4 tetrahedra, corners with four equivalent N(1)Hf4 tetrahedra, edges with two equivalent O(2)Hf6 octahedra, edges with two equivalent N(1)Hf4 tetrahedra, edges with four equivalent N(2)Hf4 tetrahedra, and edges with four equivalent N(3)Hf5 trigonal bipyramids.
Hf2ON2 crystallizes in the monoclinic C2/m space group. There are three inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one N(2), one N(3), two equivalent N(1), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedra are not tilted. The Hf(1)-N(2) bond length is 2.12 Å. The Hf(1)-N(3) bond length is 2.15 Å. Both Hf(1)-N(1) bond lengths are 2.06 Å. Both Hf(1)-O(2) bond lengths are 2.35 Å. In the second Hf site, Hf(2) is bonded in a 7-coordinate geometry to two equivalent N(1), two equivalent N(3), and three equivalent O(1) atoms. There is one shorter (2.14 Å) and one longer (2.31 Å) Hf(2)-N(1) bond length. Both Hf(2)-N(3) bond lengths are 2.24 Å. There are two shorter (2.18 Å) and one longer (2.46 Å) Hf(2)-O(1) bond length. In the third Hf site, Hf(3) is bonded in a 7-coordinate geometry to two equivalent N(3), three equivalent N(2), one O(1), and one O(2) atom. Both Hf(3)-N(3) bond lengths are 2.36 Å. There is one shorter (2.10 Å) and two longer (2.12 Å) Hf(3)-N(2) bond lengths. The Hf(3)-O(1) bond length is 2.21 Å. The Hf(3)-O(2) bond length is 2.71 Å. There are three inequivalent N sites. In the first N site, N(1) is bonded to two equivalent Hf(1) and two equivalent Hf(2) atoms to form distorted NHf4 tetrahedra that share corners with two equivalent O(2)Hf6 octahedra, corners with two equivalent N(1)Hf4 tetrahedra, corners with two equivalent N(2)Hf4 tetrahedra, corners with two equivalent N(3)Hf5 trigonal bipyramids,  an edgeedge with one O(2)Hf6 octahedra,  an edgeedge with one N(1)Hf4 tetrahedra, and edges with two equivalent N(3)Hf5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 11°. In the second N site, N(2) is bonded to one Hf(1) and three equivalent Hf(3) atoms to form NHf4 tetrahedra that share  a cornercorner with one O(2)Hf6 octahedra, corners with two equivalent N(1)Hf4 tetrahedra, corners with two equivalent N(2)Hf4 tetrahedra, corners with five equivalent N(3)Hf5 trigonal bipyramids, edges with two equivalent O(2)Hf6 octahedra, edges with two equivalent N(2)Hf4 tetrahedra, and  an edgeedge with one N(3)Hf5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 45°. In the third N site, N(3) is bonded to one Hf(1), two equivalent Hf(2), and two equivalent Hf(3) atoms to form distorted NHf5 trigonal bipyramids that share corners with two equivalent N(1)Hf4 tetrahedra, corners with five equivalent N(2)Hf4 tetrahedra, edges with two equivalent O(2)Hf6 octahedra,  an edgeedge with one N(2)Hf4 tetrahedra, edges with two equivalent N(1)Hf4 tetrahedra, and edges with two equivalent N(3)Hf5 trigonal bipyramids. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Hf(3) and three equivalent Hf(2) atoms. In the second O site, O(2) is bonded to two equivalent Hf(3) and four equivalent Hf(1) atoms to form OHf6 octahedra that share corners with two equivalent N(2)Hf4 tetrahedra, corners with four equivalent N(1)Hf4 tetrahedra, edges with two equivalent O(2)Hf6 octahedra, edges with two equivalent N(1)Hf4 tetrahedra, edges with four equivalent N(2)Hf4 tetrahedra, and edges with four equivalent N(3)Hf5 trigonal bipyramids.