Fe10CuN8 crystallizes in the monoclinic C2/m space group. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a distorted trigonal planar geometry to one N(1), one N(2), and one N(3) atom. In the second Fe site, Fe(2) is bonded in a distorted square co-planar geometry to one N(1), one N(2), and two equivalent N(4) atoms. In the third Fe site, Fe(3) is bonded in a distorted see-saw-like geometry to one N(3), one N(4), and two equivalent N(2) atoms. In the fourth Fe site, Fe(4) is bonded to two equivalent N(1) and two equivalent N(4) atoms to form FeN4 trigonal pyramids that share corners with two equivalent Fe(5)N5 square pyramids, corners with two equivalent Fe(4)N4 trigonal pyramids, and  an edgeedge with one Fe(4)N4 trigonal pyramid. In the fifth Fe site, Fe(5) is bonded to one N(1), one N(2), and three equivalent N(3) atoms to form FeN5 square pyramids that share corners with two equivalent Fe(5)N5 square pyramids, corners with two equivalent Fe(4)N4 trigonal pyramids, and edges with two equivalent Fe(5)N5 square pyramids. Cu(1) is bonded in a linear geometry to two equivalent N(4) atoms. There are four inequivalent N sites. In the first N site, N(1) is bonded to one Fe(1), one Fe(2), one Fe(5), and two equivalent Fe(4) atoms to form distorted NFe5 trigonal bipyramids that share corners with two equivalent N(4)Fe5Cu octahedra, corners with two equivalent N(1)Fe5 trigonal bipyramids, corners with two equivalent N(3)Fe5 trigonal bipyramids, corners with three equivalent N(2)Fe5 trigonal bipyramids, edges with two equivalent N(4)Fe5Cu octahedra, and  an edgeedge with one N(3)Fe5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 69°. In the second N site, N(2) is bonded to one Fe(1), one Fe(2), one Fe(5), and two equivalent Fe(3) atoms to form NFe5 trigonal bipyramids that share corners with two equivalent N(2)Fe5 trigonal bipyramids, corners with two equivalent N(3)Fe5 trigonal bipyramids, corners with three equivalent N(1)Fe5 trigonal bipyramids, edges with two equivalent N(4)Fe5Cu octahedra, and edges with two equivalent N(3)Fe5 trigonal bipyramids. In the third N site, N(3) is bonded to one Fe(1), one Fe(3), and three equivalent Fe(5) atoms to form distorted NFe5 trigonal bipyramids that share  a cornercorner with one N(4)Fe5Cu octahedra, corners with two equivalent N(1)Fe5 trigonal bipyramids, corners with two equivalent N(2)Fe5 trigonal bipyramids, corners with two equivalent N(3)Fe5 trigonal bipyramids,  an edgeedge with one N(1)Fe5 trigonal bipyramid, edges with two equivalent N(2)Fe5 trigonal bipyramids, and edges with two equivalent N(3)Fe5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 34°. In the fourth N site, N(4) is bonded to one Fe(3), two equivalent Fe(2), two equivalent Fe(4), and one Cu(1) atom to form NFe5Cu octahedra that share corners with three equivalent N(4)Fe5Cu octahedra,  a cornercorner with one N(3)Fe5 trigonal bipyramid, corners with two equivalent N(1)Fe5 trigonal bipyramids,  an edgeedge with one N(4)Fe5Cu octahedra, edges with two equivalent N(1)Fe5 trigonal bipyramids, and edges with two equivalent N(2)Fe5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-16°.
Fe10CuN8 crystallizes in the monoclinic C2/m space group. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a distorted trigonal planar geometry to one N(1), one N(2), and one N(3) atom. The Fe(1)-N(1) bond length is 1.81 Å. The Fe(1)-N(2) bond length is 1.85 Å. The Fe(1)-N(3) bond length is 1.79 Å. In the second Fe site, Fe(2) is bonded in a distorted square co-planar geometry to one N(1), one N(2), and two equivalent N(4) atoms. The Fe(2)-N(1) bond length is 2.02 Å. The Fe(2)-N(2) bond length is 2.05 Å. Both Fe(2)-N(4) bond lengths are 1.90 Å. In the third Fe site, Fe(3) is bonded in a distorted see-saw-like geometry to one N(3), one N(4), and two equivalent N(2) atoms. The Fe(3)-N(3) bond length is 1.92 Å. The Fe(3)-N(4) bond length is 2.06 Å. Both Fe(3)-N(2) bond lengths are 1.90 Å. In the fourth Fe site, Fe(4) is bonded to two equivalent N(1) and two equivalent N(4) atoms to form FeN4 trigonal pyramids that share corners with two equivalent Fe(5)N5 square pyramids, corners with two equivalent Fe(4)N4 trigonal pyramids, and  an edgeedge with one Fe(4)N4 trigonal pyramid. Both Fe(4)-N(1) bond lengths are 2.02 Å. There is one shorter (1.98 Å) and one longer (1.99 Å) Fe(4)-N(4) bond length. In the fifth Fe site, Fe(5) is bonded to one N(1), one N(2), and three equivalent N(3) atoms to form FeN5 square pyramids that share corners with two equivalent Fe(5)N5 square pyramids, corners with two equivalent Fe(4)N4 trigonal pyramids, and edges with two equivalent Fe(5)N5 square pyramids. The Fe(5)-N(1) bond length is 1.93 Å. The Fe(5)-N(2) bond length is 1.93 Å. There are two shorter (1.92 Å) and one longer (2.12 Å) Fe(5)-N(3) bond length. Cu(1) is bonded in a linear geometry to two equivalent N(4) atoms. Both Cu(1)-N(4) bond lengths are 1.86 Å. There are four inequivalent N sites. In the first N site, N(1) is bonded to one Fe(1), one Fe(2), one Fe(5), and two equivalent Fe(4) atoms to form distorted NFe5 trigonal bipyramids that share corners with two equivalent N(4)Fe5Cu octahedra, corners with two equivalent N(1)Fe5 trigonal bipyramids, corners with two equivalent N(3)Fe5 trigonal bipyramids, corners with three equivalent N(2)Fe5 trigonal bipyramids, edges with two equivalent N(4)Fe5Cu octahedra, and  an edgeedge with one N(3)Fe5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 69°. In the second N site, N(2) is bonded to one Fe(1), one Fe(2), one Fe(5), and two equivalent Fe(3) atoms to form NFe5 trigonal bipyramids that share corners with two equivalent N(2)Fe5 trigonal bipyramids, corners with two equivalent N(3)Fe5 trigonal bipyramids, corners with three equivalent N(1)Fe5 trigonal bipyramids, edges with two equivalent N(4)Fe5Cu octahedra, and edges with two equivalent N(3)Fe5 trigonal bipyramids. In the third N site, N(3) is bonded to one Fe(1), one Fe(3), and three equivalent Fe(5) atoms to form distorted NFe5 trigonal bipyramids that share  a cornercorner with one N(4)Fe5Cu octahedra, corners with two equivalent N(1)Fe5 trigonal bipyramids, corners with two equivalent N(2)Fe5 trigonal bipyramids, corners with two equivalent N(3)Fe5 trigonal bipyramids,  an edgeedge with one N(1)Fe5 trigonal bipyramid, edges with two equivalent N(2)Fe5 trigonal bipyramids, and edges with two equivalent N(3)Fe5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 34°. In the fourth N site, N(4) is bonded to one Fe(3), two equivalent Fe(2), two equivalent Fe(4), and one Cu(1) atom to form NFe5Cu octahedra that share corners with three equivalent N(4)Fe5Cu octahedra,  a cornercorner with one N(3)Fe5 trigonal bipyramid, corners with two equivalent N(1)Fe5 trigonal bipyramids,  an edgeedge with one N(4)Fe5Cu octahedra, edges with two equivalent N(1)Fe5 trigonal bipyramids, and edges with two equivalent N(2)Fe5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-16°.