MgHf8(N2O)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 4-coordinate geometry to one N(5), one N(6), one N(8), one O(1), and one O(3) 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 distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 56-65°. In the second Hf site, Hf(2) 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 a mixture of edge and face-sharing HfN4O2 octahedra. In the third Hf site, Hf(3) is bonded in a 6-coordinate geometry to one N(2), one N(5), one N(6), one N(8), one O(1), and one O(3) atom. In the fourth Hf site, Hf(4) 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 fifth Hf site, Hf(5) 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 distorted corner and face-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 42-65°. 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 edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 45-54°. In the seventh Hf site, Hf(7) is bonded in a 6-coordinate geometry to one N(2), one N(5), one N(6), one N(8), 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 a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 42-46°. There are eight inequivalent N sites. In the first N site, N(1) is bonded to one Hf(1), one Hf(4), one Hf(5), and one Hf(6) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(6)Hf4Mg trigonal bipyramids, corners with two equivalent N(3)Hf4 trigonal pyramids, and  an edgeedge with one O(4)Hf4 trigonal pyramid. In the second N site, N(2) is bonded in a 4-coordinate 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 to one Hf(2), one Hf(4), one Hf(5), and one Hf(8) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(5)Hf4Mg square pyramids, corners with two equivalent O(3)Hf4Mg square pyramids, corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids,  an edgeedge with one N(8)Hf4Mg square pyramid, and  an edgeedge with one O(4)Hf4 trigonal pyramid. In the fourth N site, N(4) is bonded in a see-saw-like 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 Mg(1), one Hf(2), one Hf(3), one Hf(7), and one Hf(8) atom to form NHf4Mg square pyramids that share  a cornercorner with one N(8)Hf4Mg square pyramid,  a cornercorner with one O(3)Hf4Mg square pyramid, corners with three equivalent N(6)Hf4Mg trigonal bipyramids, corners with two equivalent N(3)Hf4 trigonal pyramids, edges with two equivalent N(8)Hf4Mg square pyramids, edges with two equivalent O(3)Hf4Mg square pyramids, and  an edgeedge with one O(4)Hf4 trigonal pyramid. In the sixth N site, N(6) is bonded to one Mg(1), one Hf(1), one Hf(3), one Hf(6), and one Hf(7) atom to form distorted NHf4Mg trigonal bipyramids that share corners with three equivalent N(5)Hf4Mg square pyramids, corners with three equivalent N(8)Hf4Mg square pyramids, corners with two equivalent N(1)Hf4 trigonal pyramids, and  a faceface with one O(3)Hf4Mg square pyramid. In the seventh N site, N(7) is bonded in a distorted see-saw-like geometry to one Hf(2), one Hf(4), one Hf(5), and one Hf(8) atom. In the eighth N site, N(8) is bonded to one Mg(1), one Hf(2), one Hf(3), one Hf(7), and one Hf(8) atom to form distorted NHf4Mg square pyramids that share  a cornercorner with one N(5)Hf4Mg square pyramid,  a cornercorner with one O(3)Hf4Mg square pyramid, corners with three equivalent N(6)Hf4Mg trigonal bipyramids, corners with two equivalent O(4)Hf4 trigonal pyramids, edges with two equivalent N(5)Hf4Mg square pyramids, edges with two equivalent O(3)Hf4Mg square pyramids, and  an edgeedge with one N(3)Hf4 trigonal pyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Mg(1), one Hf(1), one Hf(3), 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 Mg(1), one Hf(2), one Hf(3), one Hf(7), and one Hf(8) atom to form OHf4Mg square pyramids that share  a cornercorner with one N(5)Hf4Mg square pyramid,  a cornercorner with one N(8)Hf4Mg square pyramid, corners with two equivalent N(3)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids, edges with two equivalent N(5)Hf4Mg square pyramids, edges with two equivalent N(8)Hf4Mg square pyramids, and  a faceface with one N(6)Hf4Mg trigonal bipyramid. In the fourth O site, O(4) is bonded to one Hf(2), one Hf(4), one Hf(5), and one Hf(8) atom to form distorted OHf4 trigonal pyramids that share corners with two equivalent N(8)Hf4Mg square pyramids, corners with two equivalent O(3)Hf4Mg square pyramids, corners with two equivalent N(3)Hf4 trigonal pyramids,  an edgeedge with one N(5)Hf4Mg square pyramid,  an edgeedge with one N(1)Hf4 trigonal pyramid, and  an edgeedge with one N(3)Hf4 trigonal pyramid.
MgHf8(N2O)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 4-coordinate geometry to one N(5), one N(6), one N(8), one O(1), and one O(3) atom. The Mg(1)-N(5) bond length is 2.16 Å. The Mg(1)-N(6) bond length is 2.20 Å. The Mg(1)-N(8) bond length is 2.12 Å. The Mg(1)-O(1) bond length is 2.71 Å. The Mg(1)-O(3) bond length is 2.08 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 distorted edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 56-65°. The Hf(1)-N(1) bond length is 2.16 Å. The Hf(1)-N(2) bond length is 2.30 Å. The Hf(1)-N(4) bond length is 2.11 Å. The Hf(1)-N(6) bond length is 2.35 Å. The Hf(1)-O(1) bond length is 2.25 Å. The Hf(1)-O(2) bond length is 2.09 Å. In the second Hf site, Hf(2) 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 a mixture of edge and face-sharing HfN4O2 octahedra. The Hf(2)-N(3) bond length is 2.11 Å. The Hf(2)-N(5) bond length is 2.26 Å. The Hf(2)-N(7) bond length is 2.15 Å. The Hf(2)-N(8) bond length is 2.06 Å. The Hf(2)-O(3) bond length is 2.16 Å. The Hf(2)-O(4) bond length is 2.30 Å. In the third Hf site, Hf(3) is bonded in a 6-coordinate geometry to one N(2), one N(5), one N(6), one N(8), one O(1), and one O(3) atom. The Hf(3)-N(2) bond length is 2.16 Å. The Hf(3)-N(5) bond length is 2.20 Å. The Hf(3)-N(6) bond length is 2.27 Å. The Hf(3)-N(8) bond length is 2.12 Å. The Hf(3)-O(1) bond length is 2.24 Å. The Hf(3)-O(3) bond length is 2.31 Å. In the fourth Hf site, Hf(4) 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(4)-N(1) bond length is 2.33 Å. The Hf(4)-N(3) bond length is 2.02 Å. The Hf(4)-N(4) bond length is 2.21 Å. The Hf(4)-N(7) bond length is 2.12 Å. The Hf(4)-O(2) bond length is 2.46 Å. The Hf(4)-O(4) bond length is 2.15 Å. In the fifth Hf site, Hf(5) 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 distorted corner and face-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 42-65°. The Hf(5)-N(1) bond length is 2.07 Å. The Hf(5)-N(3) bond length is 2.36 Å. The Hf(5)-N(4) bond length is 2.14 Å. The Hf(5)-N(7) bond length is 2.27 Å. The Hf(5)-O(2) bond length is 2.07 Å. The Hf(5)-O(4) bond length is 2.33 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 edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 45-54°. The Hf(6)-N(1) bond length is 2.10 Å. The Hf(6)-N(2) bond length is 2.05 Å. The Hf(6)-N(4) bond length is 2.20 Å. The Hf(6)-N(6) bond length is 2.21 Å. The Hf(6)-O(1) bond length is 2.25 Å. The Hf(6)-O(2) bond length is 2.29 Å. In the seventh Hf site, Hf(7) is bonded in a 6-coordinate geometry to one N(2), one N(5), one N(6), one N(8), one O(1), and one O(3) atom. The Hf(7)-N(2) bond length is 2.18 Å. The Hf(7)-N(5) bond length is 2.25 Å. The Hf(7)-N(6) bond length is 2.24 Å. The Hf(7)-N(8) bond length is 2.56 Å. The Hf(7)-O(1) bond length is 2.28 Å. The Hf(7)-O(3) bond length is 2.29 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 a mixture of edge and corner-sharing HfN4O2 octahedra. The corner-sharing octahedral tilt angles range from 42-46°. The Hf(8)-N(3) bond length is 2.19 Å. The Hf(8)-N(5) bond length is 2.22 Å. The Hf(8)-N(7) bond length is 2.13 Å. The Hf(8)-N(8) bond length is 2.35 Å. The Hf(8)-O(3) bond length is 2.28 Å. The Hf(8)-O(4) bond length is 2.11 Å. There are eight inequivalent N sites. In the first N site, N(1) is bonded to one Hf(1), one Hf(4), one Hf(5), and one Hf(6) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(6)Hf4Mg trigonal bipyramids, corners with two equivalent N(3)Hf4 trigonal pyramids, and  an edgeedge with one O(4)Hf4 trigonal pyramid. In the second N site, N(2) is bonded in a 4-coordinate 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 to one Hf(2), one Hf(4), one Hf(5), and one Hf(8) atom to form distorted NHf4 trigonal pyramids that share corners with two equivalent N(5)Hf4Mg square pyramids, corners with two equivalent O(3)Hf4Mg square pyramids, corners with two equivalent N(1)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids,  an edgeedge with one N(8)Hf4Mg square pyramid, and  an edgeedge with one O(4)Hf4 trigonal pyramid. In the fourth N site, N(4) is bonded in a see-saw-like 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 Mg(1), one Hf(2), one Hf(3), one Hf(7), and one Hf(8) atom to form NHf4Mg square pyramids that share  a cornercorner with one N(8)Hf4Mg square pyramid,  a cornercorner with one O(3)Hf4Mg square pyramid, corners with three equivalent N(6)Hf4Mg trigonal bipyramids, corners with two equivalent N(3)Hf4 trigonal pyramids, edges with two equivalent N(8)Hf4Mg square pyramids, edges with two equivalent O(3)Hf4Mg square pyramids, and  an edgeedge with one O(4)Hf4 trigonal pyramid. In the sixth N site, N(6) is bonded to one Mg(1), one Hf(1), one Hf(3), one Hf(6), and one Hf(7) atom to form distorted NHf4Mg trigonal bipyramids that share corners with three equivalent N(5)Hf4Mg square pyramids, corners with three equivalent N(8)Hf4Mg square pyramids, corners with two equivalent N(1)Hf4 trigonal pyramids, and  a faceface with one O(3)Hf4Mg square pyramid. In the seventh N site, N(7) is bonded in a distorted see-saw-like geometry to one Hf(2), one Hf(4), one Hf(5), and one Hf(8) atom. In the eighth N site, N(8) is bonded to one Mg(1), one Hf(2), one Hf(3), one Hf(7), and one Hf(8) atom to form distorted NHf4Mg square pyramids that share  a cornercorner with one N(5)Hf4Mg square pyramid,  a cornercorner with one O(3)Hf4Mg square pyramid, corners with three equivalent N(6)Hf4Mg trigonal bipyramids, corners with two equivalent O(4)Hf4 trigonal pyramids, edges with two equivalent N(5)Hf4Mg square pyramids, edges with two equivalent O(3)Hf4Mg square pyramids, and  an edgeedge with one N(3)Hf4 trigonal pyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Mg(1), one Hf(1), one Hf(3), 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 Mg(1), one Hf(2), one Hf(3), one Hf(7), and one Hf(8) atom to form OHf4Mg square pyramids that share  a cornercorner with one N(5)Hf4Mg square pyramid,  a cornercorner with one N(8)Hf4Mg square pyramid, corners with two equivalent N(3)Hf4 trigonal pyramids, corners with two equivalent O(4)Hf4 trigonal pyramids, edges with two equivalent N(5)Hf4Mg square pyramids, edges with two equivalent N(8)Hf4Mg square pyramids, and  a faceface with one N(6)Hf4Mg trigonal bipyramid. In the fourth O site, O(4) is bonded to one Hf(2), one Hf(4), one Hf(5), and one Hf(8) atom to form distorted OHf4 trigonal pyramids that share corners with two equivalent N(8)Hf4Mg square pyramids, corners with two equivalent O(3)Hf4Mg square pyramids, corners with two equivalent N(3)Hf4 trigonal pyramids,  an edgeedge with one N(5)Hf4Mg square pyramid,  an edgeedge with one N(1)Hf4 trigonal pyramid, and  an edgeedge with one N(3)Hf4 trigonal pyramid.