CaHf8(N2O)4 crystallizes in the triclinic P1 space group. Ca(1) is bonded in a 4-coordinate geometry to one N(3), one N(7), one N(8), and one O(4) atom. There are eight inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one N(1), one N(2), one N(4), one N(6), one O(1), and one O(2) atom to form a mixture of corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 40-52°. In the second Hf site, Hf(2) is bonded in a 5-coordinate geometry to one N(3), one N(5), one N(7), one N(8), and one O(3) atom. In the third Hf site, Hf(3) is bonded in a 5-coordinate geometry to one N(2), one N(5), one N(6), one N(8), and one O(3) atom. In the fourth Hf site, Hf(4) is bonded to one N(1), one N(3), one N(4), one N(7), one O(2), and one O(4) atom to form a mixture of face and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 18-52°. In the fifth Hf site, Hf(5) is bonded in a 6-coordinate geometry to one N(1), one N(3), one N(4), one N(7), one O(2), and one O(4) atom. In the sixth Hf site, Hf(6) is bonded to one N(1), one N(2), one N(4), one N(6), one O(1), and one O(2) atom to form a mixture of distorted face and edge-sharing HfN4O2 octahedra. In the seventh Hf site, Hf(7) is bonded in a 5-coordinate geometry to one N(2), one N(5), one N(6), one O(1), and one O(3) atom. In the eighth Hf site, Hf(8) is bonded to one N(3), one N(5), one N(7), one N(8), one O(3), and one O(4) atom to form distorted corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 18-32°. There are eight inequivalent N sites. In the first N site, N(1) is bonded in a distorted see-saw-like geometry to one Hf(1), one Hf(4), one Hf(5), and one Hf(6) atom. In the second N site, N(2) is bonded in a distorted see-saw-like geometry to one Hf(1), one Hf(3), one Hf(6), and one Hf(7) atom. In the third N site, N(3) is bonded in a 5-coordinate geometry to one Ca(1), one Hf(2), one Hf(4), one Hf(5), and one Hf(8) atom. In the fourth N site, N(4) is bonded in a 4-coordinate geometry to one Hf(1), one Hf(4), one Hf(5), and one Hf(6) atom. In the fifth N site, N(5) is bonded to one Hf(2), one Hf(3), one Hf(7), and one Hf(8) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(6)Hf4 tetrahedra, corners with two equivalent O(3)Hf4 trigonal pyramids, and  an edgeedge with one O(3)Hf4 trigonal pyramid. In the sixth N site, N(6) is bonded to one Hf(1), one Hf(3), one Hf(6), and one Hf(7) atom to form distorted NHf4 tetrahedra that share corners with two equivalent N(5)Hf4 trigonal pyramids and  an edgeedge with one O(3)Hf4 trigonal pyramid. In the seventh N site, N(7) is bonded in a 5-coordinate geometry to one Ca(1), one Hf(2), one Hf(4), one Hf(5), and one Hf(8) atom. In the eighth N site, N(8) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Hf(2), one Hf(3), and one Hf(8) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Hf(1), one Hf(6), and one Hf(7) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Hf(1), one Hf(4), one Hf(5), and one Hf(6) atom. In the third O site, O(3) is bonded to one Hf(2), one Hf(3), one Hf(7), and one Hf(8) atom to form OHf4 trigonal pyramids that share corners with two equivalent N(5)Hf4 trigonal pyramids,  an edgeedge with one N(6)Hf4 tetrahedra, and  an edgeedge with one N(5)Hf4 trigonal pyramid. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Hf(4), one Hf(5), and one Hf(8) atom.
CaHf8(N2O)4 crystallizes in the triclinic P1 space group. Ca(1) is bonded in a 4-coordinate geometry to one N(3), one N(7), one N(8), and one O(4) atom. The Ca(1)-N(3) bond length is 2.51 Å. The Ca(1)-N(7) bond length is 2.38 Å. The Ca(1)-N(8) bond length is 2.53 Å. The Ca(1)-O(4) bond length is 2.33 Å. There are eight inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one N(1), one N(2), one N(4), one N(6), one O(1), and one O(2) atom to form a mixture of corner and edge-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 40-52°. The Hf(1)-N(1) bond length is 2.19 Å. The Hf(1)-N(2) bond length is 2.32 Å. The Hf(1)-N(4) bond length is 2.12 Å. The Hf(1)-N(6) bond length is 2.20 Å. The Hf(1)-O(1) bond length is 2.19 Å. The Hf(1)-O(2) bond length is 2.12 Å. In the second Hf site, Hf(2) is bonded in a 5-coordinate geometry to one N(3), one N(5), one N(7), one N(8), and one O(3) atom. The Hf(2)-N(3) bond length is 2.27 Å. The Hf(2)-N(5) bond length is 2.12 Å. The Hf(2)-N(7) bond length is 2.29 Å. The Hf(2)-N(8) bond length is 2.07 Å. The Hf(2)-O(3) bond length is 2.21 Å. In the third Hf site, Hf(3) is bonded in a 5-coordinate geometry to one N(2), one N(5), one N(6), one N(8), and one O(3) atom. The Hf(3)-N(2) bond length is 2.25 Å. The Hf(3)-N(5) bond length is 2.16 Å. The Hf(3)-N(6) bond length is 2.27 Å. The Hf(3)-N(8) bond length is 2.09 Å. The Hf(3)-O(3) bond length is 2.14 Å. In the fourth Hf site, Hf(4) is bonded to one N(1), one N(3), one N(4), one N(7), one O(2), and one O(4) atom to form a mixture of face and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 18-52°. The Hf(4)-N(1) bond length is 2.18 Å. The Hf(4)-N(3) bond length is 2.06 Å. The Hf(4)-N(4) bond length is 2.22 Å. The Hf(4)-N(7) bond length is 2.09 Å. The Hf(4)-O(2) bond length is 2.28 Å. The Hf(4)-O(4) bond length is 2.08 Å. In the fifth Hf site, Hf(5) is bonded in a 6-coordinate geometry to one N(1), one N(3), one N(4), one N(7), one O(2), and one O(4) atom. The Hf(5)-N(1) bond length is 2.14 Å. The Hf(5)-N(3) bond length is 2.57 Å. The Hf(5)-N(4) bond length is 2.13 Å. The Hf(5)-N(7) bond length is 2.16 Å. The Hf(5)-O(2) bond length is 2.24 Å. The Hf(5)-O(4) bond length is 2.15 Å. In the sixth Hf site, Hf(6) is bonded to one N(1), one N(2), one N(4), one N(6), one O(1), and one O(2) atom to form a mixture of distorted face and edge-sharing HfN4O2 octahedra. The Hf(6)-N(1) bond length is 2.22 Å. The Hf(6)-N(2) bond length is 2.03 Å. The Hf(6)-N(4) bond length is 2.41 Å. The Hf(6)-N(6) bond length is 2.09 Å. The Hf(6)-O(1) bond length is 2.14 Å. The Hf(6)-O(2) bond length is 2.52 Å. In the seventh Hf site, Hf(7) is bonded in a 5-coordinate geometry to one N(2), one N(5), one N(6), one O(1), and one O(3) atom. The Hf(7)-N(2) bond length is 2.06 Å. The Hf(7)-N(5) bond length is 2.14 Å. The Hf(7)-N(6) bond length is 2.15 Å. The Hf(7)-O(1) bond length is 2.08 Å. The Hf(7)-O(3) bond length is 2.28 Å. In the eighth Hf site, Hf(8) is bonded to one N(3), one N(5), one N(7), one N(8), one O(3), and one O(4) atom to form distorted corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 18-32°. The Hf(8)-N(3) bond length is 2.12 Å. The Hf(8)-N(5) bond length is 2.23 Å. The Hf(8)-N(7) bond length is 2.33 Å. The Hf(8)-N(8) bond length is 2.17 Å. The Hf(8)-O(3) bond length is 2.15 Å. The Hf(8)-O(4) bond length is 2.18 Å. There are eight inequivalent N sites. In the first N site, N(1) is bonded in a distorted see-saw-like geometry to one Hf(1), one Hf(4), one Hf(5), and one Hf(6) atom. In the second N site, N(2) is bonded in a distorted see-saw-like geometry to one Hf(1), one Hf(3), one Hf(6), and one Hf(7) atom. In the third N site, N(3) is bonded in a 5-coordinate geometry to one Ca(1), one Hf(2), one Hf(4), one Hf(5), and one Hf(8) atom. In the fourth N site, N(4) is bonded in a 4-coordinate geometry to one Hf(1), one Hf(4), one Hf(5), and one Hf(6) atom. In the fifth N site, N(5) is bonded to one Hf(2), one Hf(3), one Hf(7), and one Hf(8) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(6)Hf4 tetrahedra, corners with two equivalent O(3)Hf4 trigonal pyramids, and  an edgeedge with one O(3)Hf4 trigonal pyramid. In the sixth N site, N(6) is bonded to one Hf(1), one Hf(3), one Hf(6), and one Hf(7) atom to form distorted NHf4 tetrahedra that share corners with two equivalent N(5)Hf4 trigonal pyramids and  an edgeedge with one O(3)Hf4 trigonal pyramid. In the seventh N site, N(7) is bonded in a 5-coordinate geometry to one Ca(1), one Hf(2), one Hf(4), one Hf(5), and one Hf(8) atom. In the eighth N site, N(8) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Hf(2), one Hf(3), and one Hf(8) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Hf(1), one Hf(6), and one Hf(7) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Hf(1), one Hf(4), one Hf(5), and one Hf(6) atom. In the third O site, O(3) is bonded to one Hf(2), one Hf(3), one Hf(7), and one Hf(8) atom to form OHf4 trigonal pyramids that share corners with two equivalent N(5)Hf4 trigonal pyramids,  an edgeedge with one N(6)Hf4 tetrahedra, and  an edgeedge with one N(5)Hf4 trigonal pyramid. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Hf(4), one Hf(5), and one Hf(8) atom.