Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. There are eight inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one N(1), one N(3), one N(6), one N(8), one O(1), and one O(4) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 44-64°. In the second Hf site, Hf(2) is bonded to one N(2), one N(4), one N(5), one N(7), one O(2), and one O(3) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 42-66°. In the third Hf site, Hf(3) is bonded to one N(1), one N(2), one N(3), one N(4), one O(1), and one O(2) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 46-66°. In the fourth Hf site, Hf(4) is bonded to one N(5), one N(6), one N(7), one N(8), one O(3), and one O(4) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 44-66°. In the fifth Hf site, Hf(5) is bonded to one N(1), one N(2), one N(3), one N(4), one O(1), and one O(2) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 42-64°. In the sixth Hf site, Hf(6) is bonded to one N(5), one N(6), one N(7), one N(8), one O(3), and one O(4) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 47-67°. In the seventh Hf site, Hf(7) is bonded to one N(2), one N(4), one N(5), one N(7), one O(2), and one O(3) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 45-67°. In the eighth Hf site, Hf(8) is bonded to one N(1), one N(3), one N(6), one N(8), one O(1), and one O(4) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 46-66°. There are eight inequivalent N sites. In the first N site, N(1) is bonded to one Hf(1), one Hf(3), one Hf(5), and one Hf(8) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(3)Hf4 trigonal pyramids, corners with two equivalent N(6)Hf4 trigonal pyramids, corners with two equivalent O(1)Hf4 trigonal pyramids, corners with two equivalent O(2)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids,  an edgeedge with one N(2)Hf4 trigonal pyramid,  an edgeedge with one N(3)Hf4 trigonal pyramid, and  an edgeedge with one O(1)Hf4 trigonal pyramid. In the second N site, N(2) is bonded to one Hf(2), one Hf(3), one Hf(5), and one Hf(7) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(3)Hf4 trigonal pyramids, corners with two equivalent N(5)Hf4 trigonal pyramids, corners with two equivalent O(1)Hf4 trigonal pyramids, corners with two equivalent O(2)Hf4 trigonal pyramids, corners with two equivalent O(3)Hf4 trigonal pyramids,  an edgeedge with one N(1)Hf4 trigonal pyramid,  an edgeedge with one N(7)Hf4 trigonal pyramid, and  an edgeedge with one O(2)Hf4 trigonal pyramid. In the third N site, N(3) is bonded to one Hf(1), one Hf(3), one Hf(5), and one Hf(8) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent N(2)Hf4 trigonal pyramids, corners with two equivalent O(1)Hf4 trigonal pyramids, corners with two equivalent O(2)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids,  an edgeedge with one N(1)Hf4 trigonal pyramid,  an edgeedge with one N(6)Hf4 trigonal pyramid, and  an edgeedge with one O(1)Hf4 trigonal pyramid. In the fourth N site, N(4) is bonded in a distorted see-saw-like geometry to one Hf(2), one Hf(3), one Hf(5), and one Hf(7) atom. In the fifth N site, N(5) is bonded to one Hf(2), one Hf(4), one Hf(6), and one Hf(7) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(2)Hf4 trigonal pyramids, corners with two equivalent N(6)Hf4 trigonal pyramids, corners with two equivalent N(7)Hf4 trigonal pyramids, corners with two equivalent O(3)Hf4 trigonal pyramids,  an edgeedge with one N(7)Hf4 trigonal pyramid,  an edgeedge with one O(2)Hf4 trigonal pyramid,  an edgeedge with one O(3)Hf4 trigonal pyramid, and  an edgeedge with one O(4)Hf4 trigonal pyramid. In the sixth N site, N(6) is bonded to one Hf(1), one Hf(4), one Hf(6), and one Hf(8) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent N(5)Hf4 trigonal pyramids, corners with two equivalent N(7)Hf4 trigonal pyramids, corners with two equivalent O(1)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids,  an edgeedge with one N(3)Hf4 trigonal pyramid,  an edgeedge with one O(3)Hf4 trigonal pyramid, and  an edgeedge with one O(4)Hf4 trigonal pyramid. In the seventh N site, N(7) is bonded to one Hf(2), one Hf(4), one Hf(6), and one Hf(7) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(5)Hf4 trigonal pyramids, corners with two equivalent N(6)Hf4 trigonal pyramids, corners with two equivalent O(2)Hf4 trigonal pyramids, corners with two equivalent O(3)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids,  an edgeedge with one N(2)Hf4 trigonal pyramid,  an edgeedge with one N(5)Hf4 trigonal pyramid, and  an edgeedge with one O(3)Hf4 trigonal pyramid. In the eighth N site, N(8) is bonded in a distorted see-saw-like geometry to one Hf(1), one Hf(4), one Hf(6), and one Hf(8) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Hf(1), one Hf(3), one Hf(5), and one Hf(8) atom to form distorted OHf4 trigonal pyramids that share corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent N(2)Hf4 trigonal pyramids, corners with two equivalent N(3)Hf4 trigonal pyramids, corners with two equivalent N(6)Hf4 trigonal pyramids,  an edgeedge with one N(1)Hf4 trigonal pyramid,  an edgeedge with one N(3)Hf4 trigonal pyramid,  an edgeedge with one O(2)Hf4 trigonal pyramid, and  an edgeedge with one O(4)Hf4 trigonal pyramid. In the second O site, O(2) is bonded to one Hf(2), one Hf(3), one Hf(5), and one Hf(7) atom to form distorted OHf4 trigonal pyramids that share corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent N(2)Hf4 trigonal pyramids, corners with two equivalent N(3)Hf4 trigonal pyramids, corners with two equivalent N(7)Hf4 trigonal pyramids, corners with two equivalent O(3)Hf4 trigonal pyramids,  an edgeedge with one N(2)Hf4 trigonal pyramid,  an edgeedge with one N(5)Hf4 trigonal pyramid, and  an edgeedge with one O(1)Hf4 trigonal pyramid. In the third O site, O(3) is bonded to one Hf(2), one Hf(4), one Hf(6), and one Hf(7) atom to form distorted OHf4 trigonal pyramids that share corners with two equivalent N(2)Hf4 trigonal pyramids, corners with two equivalent N(5)Hf4 trigonal pyramids, corners with two equivalent N(7)Hf4 trigonal pyramids, corners with two equivalent O(2)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids,  an edgeedge with one N(5)Hf4 trigonal pyramid,  an edgeedge with one N(6)Hf4 trigonal pyramid, and  an edgeedge with one N(7)Hf4 trigonal pyramid. In the fourth O site, O(4) is bonded to one Hf(1), one Hf(4), one Hf(6), and one Hf(8) atom to form distorted OHf4 trigonal pyramids that share corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent N(3)Hf4 trigonal pyramids, corners with two equivalent N(6)Hf4 trigonal pyramids, corners with two equivalent N(7)Hf4 trigonal pyramids, corners with two equivalent O(3)Hf4 trigonal pyramids,  an edgeedge with one N(5)Hf4 trigonal pyramid,  an edgeedge with one N(6)Hf4 trigonal pyramid, and  an edgeedge with one O(1)Hf4 trigonal pyramid.
Hf2ON2 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. There are eight inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one N(1), one N(3), one N(6), one N(8), one O(1), and one O(4) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 44-64°. The Hf(1)-N(1) bond length is 2.07 Å. The Hf(1)-N(3) bond length is 2.11 Å. The Hf(1)-N(6) bond length is 2.18 Å. The Hf(1)-N(8) bond length is 2.25 Å. The Hf(1)-O(1) bond length is 2.16 Å. The Hf(1)-O(4) bond length is 2.39 Å. In the second Hf site, Hf(2) is bonded to one N(2), one N(4), one N(5), one N(7), one O(2), and one O(3) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 42-66°. The Hf(2)-N(2) bond length is 2.16 Å. The Hf(2)-N(4) bond length is 2.09 Å. The Hf(2)-N(5) bond length is 2.20 Å. The Hf(2)-N(7) bond length is 2.33 Å. The Hf(2)-O(2) bond length is 2.08 Å. The Hf(2)-O(3) bond length is 2.27 Å. In the third Hf site, Hf(3) is bonded to one N(1), one N(2), one N(3), one N(4), one O(1), and one O(2) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 46-66°. The Hf(3)-N(1) bond length is 2.18 Å. The Hf(3)-N(2) bond length is 2.11 Å. The Hf(3)-N(3) bond length is 2.29 Å. The Hf(3)-N(4) bond length is 2.09 Å. The Hf(3)-O(1) bond length is 2.32 Å. The Hf(3)-O(2) bond length is 2.14 Å. In the fourth Hf site, Hf(4) is bonded to one N(5), one N(6), one N(7), one N(8), one O(3), and one O(4) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 44-66°. The Hf(4)-N(5) bond length is 2.23 Å. The Hf(4)-N(6) bond length is 2.15 Å. The Hf(4)-N(7) bond length is 2.16 Å. The Hf(4)-N(8) bond length is 2.04 Å. The Hf(4)-O(3) bond length is 2.44 Å. The Hf(4)-O(4) bond length is 2.17 Å. In the fifth Hf site, Hf(5) is bonded to one N(1), one N(2), one N(3), one N(4), one O(1), and one O(2) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 42-64°. The Hf(5)-N(1) bond length is 2.11 Å. The Hf(5)-N(2) bond length is 2.23 Å. The Hf(5)-N(3) bond length is 2.06 Å. The Hf(5)-N(4) bond length is 2.24 Å. The Hf(5)-O(1) bond length is 2.15 Å. The Hf(5)-O(2) bond length is 2.35 Å. In the sixth Hf site, Hf(6) is bonded to one N(5), one N(6), one N(7), one N(8), one O(3), and one O(4) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 47-67°. The Hf(6)-N(5) bond length is 2.09 Å. The Hf(6)-N(6) bond length is 2.23 Å. The Hf(6)-N(7) bond length is 2.16 Å. The Hf(6)-N(8) bond length is 2.30 Å. The Hf(6)-O(3) bond length is 2.08 Å. The Hf(6)-O(4) bond length is 2.26 Å. In the seventh Hf site, Hf(7) is bonded to one N(2), one N(4), one N(5), one N(7), one O(2), and one O(3) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 45-67°. The Hf(7)-N(2) bond length is 2.18 Å. The Hf(7)-N(4) bond length is 2.24 Å. The Hf(7)-N(5) bond length is 2.15 Å. The Hf(7)-N(7) bond length is 2.04 Å. The Hf(7)-O(2) bond length is 2.38 Å. The Hf(7)-O(3) bond length is 2.17 Å. In the eighth Hf site, Hf(8) is bonded to one N(1), one N(3), one N(6), one N(8), one O(1), and one O(4) atom to form a mixture of distorted edge, face, and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 46-66°. The Hf(8)-N(1) bond length is 2.30 Å. The Hf(8)-N(3) bond length is 2.19 Å. The Hf(8)-N(6) bond length is 2.11 Å. The Hf(8)-N(8) bond length is 2.08 Å. The Hf(8)-O(1) bond length is 2.32 Å. The Hf(8)-O(4) bond length is 2.13 Å. There are eight inequivalent N sites. In the first N site, N(1) is bonded to one Hf(1), one Hf(3), one Hf(5), and one Hf(8) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(3)Hf4 trigonal pyramids, corners with two equivalent N(6)Hf4 trigonal pyramids, corners with two equivalent O(1)Hf4 trigonal pyramids, corners with two equivalent O(2)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids,  an edgeedge with one N(2)Hf4 trigonal pyramid,  an edgeedge with one N(3)Hf4 trigonal pyramid, and  an edgeedge with one O(1)Hf4 trigonal pyramid. In the second N site, N(2) is bonded to one Hf(2), one Hf(3), one Hf(5), and one Hf(7) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(3)Hf4 trigonal pyramids, corners with two equivalent N(5)Hf4 trigonal pyramids, corners with two equivalent O(1)Hf4 trigonal pyramids, corners with two equivalent O(2)Hf4 trigonal pyramids, corners with two equivalent O(3)Hf4 trigonal pyramids,  an edgeedge with one N(1)Hf4 trigonal pyramid,  an edgeedge with one N(7)Hf4 trigonal pyramid, and  an edgeedge with one O(2)Hf4 trigonal pyramid. In the third N site, N(3) is bonded to one Hf(1), one Hf(3), one Hf(5), and one Hf(8) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent N(2)Hf4 trigonal pyramids, corners with two equivalent O(1)Hf4 trigonal pyramids, corners with two equivalent O(2)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids,  an edgeedge with one N(1)Hf4 trigonal pyramid,  an edgeedge with one N(6)Hf4 trigonal pyramid, and  an edgeedge with one O(1)Hf4 trigonal pyramid. In the fourth N site, N(4) is bonded in a distorted see-saw-like geometry to one Hf(2), one Hf(3), one Hf(5), and one Hf(7) atom. In the fifth N site, N(5) is bonded to one Hf(2), one Hf(4), one Hf(6), and one Hf(7) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(2)Hf4 trigonal pyramids, corners with two equivalent N(6)Hf4 trigonal pyramids, corners with two equivalent N(7)Hf4 trigonal pyramids, corners with two equivalent O(3)Hf4 trigonal pyramids,  an edgeedge with one N(7)Hf4 trigonal pyramid,  an edgeedge with one O(2)Hf4 trigonal pyramid,  an edgeedge with one O(3)Hf4 trigonal pyramid, and  an edgeedge with one O(4)Hf4 trigonal pyramid. In the sixth N site, N(6) is bonded to one Hf(1), one Hf(4), one Hf(6), and one Hf(8) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent N(5)Hf4 trigonal pyramids, corners with two equivalent N(7)Hf4 trigonal pyramids, corners with two equivalent O(1)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids,  an edgeedge with one N(3)Hf4 trigonal pyramid,  an edgeedge with one O(3)Hf4 trigonal pyramid, and  an edgeedge with one O(4)Hf4 trigonal pyramid. In the seventh N site, N(7) is bonded to one Hf(2), one Hf(4), one Hf(6), and one Hf(7) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(5)Hf4 trigonal pyramids, corners with two equivalent N(6)Hf4 trigonal pyramids, corners with two equivalent O(2)Hf4 trigonal pyramids, corners with two equivalent O(3)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids,  an edgeedge with one N(2)Hf4 trigonal pyramid,  an edgeedge with one N(5)Hf4 trigonal pyramid, and  an edgeedge with one O(3)Hf4 trigonal pyramid. In the eighth N site, N(8) is bonded in a distorted see-saw-like geometry to one Hf(1), one Hf(4), one Hf(6), and one Hf(8) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Hf(1), one Hf(3), one Hf(5), and one Hf(8) atom to form distorted OHf4 trigonal pyramids that share corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent N(2)Hf4 trigonal pyramids, corners with two equivalent N(3)Hf4 trigonal pyramids, corners with two equivalent N(6)Hf4 trigonal pyramids,  an edgeedge with one N(1)Hf4 trigonal pyramid,  an edgeedge with one N(3)Hf4 trigonal pyramid,  an edgeedge with one O(2)Hf4 trigonal pyramid, and  an edgeedge with one O(4)Hf4 trigonal pyramid. In the second O site, O(2) is bonded to one Hf(2), one Hf(3), one Hf(5), and one Hf(7) atom to form distorted OHf4 trigonal pyramids that share corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent N(2)Hf4 trigonal pyramids, corners with two equivalent N(3)Hf4 trigonal pyramids, corners with two equivalent N(7)Hf4 trigonal pyramids, corners with two equivalent O(3)Hf4 trigonal pyramids,  an edgeedge with one N(2)Hf4 trigonal pyramid,  an edgeedge with one N(5)Hf4 trigonal pyramid, and  an edgeedge with one O(1)Hf4 trigonal pyramid. In the third O site, O(3) is bonded to one Hf(2), one Hf(4), one Hf(6), and one Hf(7) atom to form distorted OHf4 trigonal pyramids that share corners with two equivalent N(2)Hf4 trigonal pyramids, corners with two equivalent N(5)Hf4 trigonal pyramids, corners with two equivalent N(7)Hf4 trigonal pyramids, corners with two equivalent O(2)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids,  an edgeedge with one N(5)Hf4 trigonal pyramid,  an edgeedge with one N(6)Hf4 trigonal pyramid, and  an edgeedge with one N(7)Hf4 trigonal pyramid. In the fourth O site, O(4) is bonded to one Hf(1), one Hf(4), one Hf(6), and one Hf(8) atom to form distorted OHf4 trigonal pyramids that share corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent N(3)Hf4 trigonal pyramids, corners with two equivalent N(6)Hf4 trigonal pyramids, corners with two equivalent N(7)Hf4 trigonal pyramids, corners with two equivalent O(3)Hf4 trigonal pyramids,  an edgeedge with one N(5)Hf4 trigonal pyramid,  an edgeedge with one N(6)Hf4 trigonal pyramid, and  an edgeedge with one O(1)Hf4 trigonal pyramid.